oversight

Climate Change: Information on Three Air Pollutants' Climate Effects and Emissions Trends

Published by the Government Accountability Office on 2003-04-28.

Below is a raw (and likely hideous) rendition of the original report. (PDF)

             United States General Accounting Office

GAO          Report to Congressional Requesters




April 2003
             CLIMATE CHANGE
             Information on
             Three Air Pollutants’
             Climate Effects and
             Emissions Trends




GAO-03-25
             a
                                               April 2003


                                               CLIMATE CHANGE

                                               Information on Three Air Pollutants’
Highlights of GAO-03-25, a report to
Congressional Requesters, House of             Climate Effects and Emissions Trends
Representatives




Solar radiation is absorbed by the             Scientists generally agree that sulfate aerosols have a cooling effect on
earth and is subsequently                      climate, while ozone in the lower atmosphere has a warming effect. Black
reemitted. The buildup of carbon               carbon tends to warm the atmosphere but cool the earth’s surface. Sulfate
dioxide and certain other gases in             aerosols also affect how much and where it rains. Considerable uncertainty
the earth’s atmosphere traps some              remains about the size of these effects.
of that radiation. This is known as
the greenhouse effect and is
believed to contribute to a warming            All seven countries are taking steps to reduce the amounts of the three
of the earth’s climate. Concerns are           pollutants. The four economically developed countries have well-established
growing that, in addition to carbon            efforts underway. In these countries, the amounts of the three substances
dioxide and other conventional                 generally declined over the last 2 decades and are expected to decline over
greenhouse gases, certain air                  the next decade. In contrast, the three developing countries’ efforts are less
pollutants may affect the climate.             well established. In these countries, the amounts of the three substances
                                               generally increased during the years for which information is available. GAO
GAO was asked to examine (1) the               found few projections for these three countries.
extent of agreement among
scientists regarding the effect on             An extensive body of research has examined the possible connection
the climate of three air pollutants—
black carbon (soot), ground-level
                                               between economic development and environmental pollution, but the results
ozone, and sulfate aerosols—and                of this research are inconclusive. Researchers also caution that economic
(2) seven countries’ efforts to                growth by itself may help support environmental improvements but is not,
control these pollutants, trends in            by itself, sufficient to ensure them.
these substances in these countries
over the past 2 decades, and                   Projected Average Global Ozone Concentrations, Parts per Billion, 2025
estimates for the next decade. GAO
was also asked to summarize the
relationship between economic
growth and environmental
pollution.

The seven countries include four
that are economically developed—
Germany, Japan, the United
Kingdom, and the United States—
and three that are developing—
China, India, and Mexico. These
countries were chosen because
they have large economies with a
high potential to emit these
pollutants.

The two federal agencies asked to
comment generally agreed with the
information presented in this
report.
www.gao.gov/cgi-bin/getrpt?GAO-03-25.

To view the full report, including the scope
and methodology, click on the link above.
For more information, contact John B.
Stephenson at (202) 512-3841.
Contents



Transmittal Letter                                                                                         1
                             Results in Brief                                                              4
                             Background                                                                    6
                             Scientists Agree on the Overall Direction of the Three Pollutants’
                               Climate Impacts, but the Estimates of Impacts Contain
                               Significant Uncertainties                                                  13
                             The Three Pollutants Are Generally Declining in Economically
                               Developed Countries, but Not in Developing Countries; All Seven
                               Countries Are Acting to Reduce Emissions                                   18
                             Studies of the Effect of Economic Growth on the Environment
                               Are Inconclusive                                                           44
                             Conclusions                                                                  51
                             Agency Comments                                                              52


Appendixes
               Appendix I:   Scope and Methodology                                                        54
              Appendix II:   Programs and Measures to Reduce Emissions of
                             Sulfur Dioxide                                                               56
             Appendix III:   Programs and Measures to Reduce Emissions of
                             Black Carbon or Particulate Matter                                           58
              Appendix IV:   Programs and Measures to Reduce Ground-Level Ozone                           59
              Appendix V:    Summary of Results of Selected Studies
                             on Economic Growth and Environmental Pollution                               61
              Appendix VI:   GAO Contact and Staff Acknowledgments                                        62



Tables                       Table 1: Comparative Statistics of the Seven Countries
                                      Reviewed                                                            12
                             Table 2: Results of Selected Studies of Economic Growth and
                                      Environmental Quality                                               61


Figures                      Figure 1: Sources and Estimated Mean Atmospheric Lifetimes of
                                       Selected Substances Affecting Climate                               8
                             Figure 2: Direct Effects of Several Substances on Climate Change
                                       as Reported in the IPCC’s Third Assessment
                                       Report, 2001                                                       14




                             Page i                               GAO-03-25 Air Pollutants and Climate Change
Contents




Figure 3: Sulfur Dioxide Emissions in Four Developed Countries,
           1980-99                                                                         19
Figure 4: Projected Sulfur Dioxide Emissions in Four Developed
           Countries, 1990-2010                                                            20
Figure 5: Sulfur Dioxide Emissions in China and Mexico,
           Selected Years                                                                  24
Figure 6: Black Carbon Emissions in the United States,
           United Kingdom, Germany, and Japan, 1980-96                                     29
Figure 7: Black Carbon Emissions in China, India, and Mexico,
           1980-96                                                                         33
Figure 8: Annually Averaged Global Ozone Concentrations at
           5 Kilometers, Parts per Billion, 1990                                           38
Figure 9: Projected Annually Averaged Global Ozone
           Concentrations at 5 Kilometers, Parts per Billion, 2025                         39
Figure 10: Number of Areas Exceeding the Ozone Standard,
           United States and Germany, 1990-2000                                            41
Figure 11: Hypothetical Inverted U-Shaped Curve, Showing
           Relationship Between Per Capita Income and
           Environmental Pollution                                                         45
Figure 12: Estimated Turning Points Found in Selected
           Studies of Particulate Matter, Sulfur Dioxide, and
           Carbon Dioxide                                                                  48




Abbreviations

CLRTAP       Convention on Long-Range Transboundary Air Pollution
EIA          Energy Information Administration
EPA          Environmental Protection Agency
EU           European Union
IPCC         Intergovernmental Panel on Climate Change
UNFCCC       United Nations Framework Convention on Climate Change


 This is a work of the U.S. Government and is not subject to copyright protection in the
 United States. It may be reproduced and distributed in its entirety without further
 permission from GAO. It may contain copyrighted graphics, images or other materials.
 Permission from the copyright holder may be necessary should you wish to reproduce
 copyrighted materials separately from GAO’s product.




Page ii                                      GAO-03-25 Air Pollutants and Climate Change
A
United States General Accounting Office
Washington, D.C. 20548



                                    April 28, 2003                                                                   T
                                                                                                                     ransmL
                                                                                                                          ta
                                                                                                                           ileter




                                    The Honorable W. J. (Billy) Tauzin
                                    Chairman
                                    Committee on Energy and Commerce
                                    House of Representatives

                                    The Honorable Joe Barton
                                    Chairman, Subcommittee on Energy and Air Quality
                                    Committee on Energy and Commerce
                                    House of Representatives

                                    The Honorable James C. Greenwood
                                    Chairman, Subcommittee on Oversight and Investigations
                                    Committee on Energy and Commerce
                                    House of Representatives

                                    Carbon dioxide and certain other gases in the earth’s atmosphere trap the
                                    sun’s heat and prevent it from escaping back into space. This phenomenon,
                                    known as the greenhouse effect, tends to warm the earth’s surface; the
                                    gases that cause it are called greenhouse gases. Most scientists agree that
                                    a change in the earth’s climate could have wide-ranging effects on
                                    economies, ecosystems, and human habitation. Climate change could make
                                    some locations unsuitable for growing traditional crops, which could lead
                                    to economic disruptions, especially in agricultural economies. However,
                                    warming is not the only issue of concern with respect to greenhouse gas
                                    emissions. A buildup of such gases could also alter precipitation patterns,
                                    causing some areas to receive more rain and others to become drier.
                                    Extreme events, such as drought or floods, could become more frequent. In
                                    addition, if climate change causes sea levels to rise substantially, low-lying
                                    areas might become uninhabitable, forcing the dislocation of entire
                                    populations. Evidence suggests that climate change is the result of both
                                    human actions (such as fossil fuel burning) and natural phenomena (such
                                    as solar variability). However, according to an international panel of
                                    experts, most of the warming observed over the past 50 years is
                                    attributable to human activities.

                                    In recent decades, concentrations of greenhouse gases have built up
                                    in the atmosphere. Concerned about these increased concentrations,
                                    the United States and many other nations entered into a treaty to
                                    stabilize atmospheric concentrations of greenhouse gases at levels that
                                    would prevent dangerous human interference with the climate system.



                                    Page 1                                 GAO-03-25 Air Pollutants and Climate Change
The United States ratified this treaty, the United Nations Framework
Convention on Climate Change (UNFCCC), in 1992. Of the gases covered
by the treaty, the most important in terms of contribution to warming, are,
in declining order of emissions levels, carbon dioxide, methane, nitrous
oxide, and three types of synthetic (manufactured) gases.

In addition, scientists have recently intensified their efforts to study the
climate effects of substances not included in the Framework Convention.
According to a 2001 comprehensive review1 of scientific research on
climate change, additional substances—generally regarded as air
pollutants because they can damage human health and the environment—
can also affect the earth’s climate. Among the substances are the three
treated in this report, listed below. Of these three, sulfate aerosols exert the
greatest influence on climate.

• Sulfate aerosols are produced when sulfur dioxide gas is transformed
  through oxidation2 in the atmosphere into aerosol particles. (An aerosol
  is a solid and/or liquid particle suspended in the air.) Sulfur dioxide is
  produced mainly by burning coal and petroleum products that
  contain sulfur.

• Black carbon is a type of aerosol produced by the incomplete
  burning of substances containing carbon. Significant sources include
  uncontrolled or poorly controlled combustion of coal, diesel fuel, and
  biomass for heating and cooking, and by the burning of fields and
  forests. Black carbon emissions from these sources are accompanied by
  varying amounts of particulate organic materials.




1
  Intergovernmental Panel on Climate Change (IPCC), 2001. Climate Change 2001: The
Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the
Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge,
United Kingdom and New York, New York.
2
    Oxidation is a type of chemical reaction involving oxygen.




Page 2                                          GAO-03-25 Air Pollutants and Climate Change
• Tropospheric ozone3 is formed when nitrogen oxides react with
  certain other chemicals in the presence of sunlight. Nitrogen oxides are
  produced primarily by cars and other vehicles and by power plants that
  burn fuel to generate electricity. On a global scale, methane and carbon
  monoxide are also significant precursors to ozone.

You asked us to (1) assess the extent to which the scientific community
agrees on the climate effects of sulfate aerosols, black carbon, and ozone,
as reflected in the 2001 review, and identify important developments since
that review, and (2) identify trends in emissions and concentrations of
these three substances over the past 2 decades in the United States and
six other specified countries, identify projected estimates in emissions and
concentrations of these pollutants in all seven countries over the next
decade, and determine each country’s actions to reduce these three
pollutants. In addition, you asked us to review the existing literature on
the effect of economic development on a country’s pollution levels to
determine whether, as some researchers have suggested, there is a
systematic connection between growth in income and emissions. As
agreed with your offices, we examined the United States and three other
economically developed countries (Germany, Japan, and the United
Kingdom) and three economically developing countries (China, India, and
Mexico). These countries were chosen because they have large economies
with a high potential to produce the substances we examined.

To obtain information on recent research relating to the climate change
characteristics of the three substances, we relied primarily on the Third
Assessment Report, the most comprehensive source on climate science.
We also contacted scientists in four federal agencies, who were
recommended by staff at the U.S. Climate Change Science Program, which
coordinates and supports government research on climate change. To learn
about work subsequent to the 2001 review, we reviewed published work
recommended by experts in the field. In obtaining data on emissions trends
and projections, we found that data from government and academic

3
  Wherever it is found, ozone is chemically the same, a molecule comprised of three oxygen
atoms. Its effects depend on its location. In the earth’s upper atmosphere (called the
stratosphere), ozone is beneficial because it prevents ultraviolet radiation—which is
dangerous to human health—from reaching the earth’s surface. However, at lower levels
(called the troposphere), it is harmful to human health. Ozone in the stratosphere also has
impacts on climate. It is formed by different means than ozone in the troposphere. We do
not discuss stratospheric ozone at length in this report because it is produced mainly
through natural (non-human-induced) processes. Unless otherwise stated, when we refer to
ozone, we are referring to tropospheric ozone.




Page 3                                       GAO-03-25 Air Pollutants and Climate Change
                   sources in the United States and the other six countries varied considerably
                   in terms of quality and availability. In cases where no other estimates were
                   available, we used results prepared by leading researchers in the field.
                   With respect to the types of policy measures reviewed, we concentrated
                   on regulatory measures and did not include research and development
                   programs, programs of a voluntary nature, emissions monitoring
                   requirements, or programs to disseminate information or educate the
                   public. We further focused on existing programs or programs already
                   authorized and excluded proposed programs. We also excluded the
                   policies and measures taking place at the sub-national level (state or
                   province level, for example), which are separate from, though sometimes
                   complementary to, national measures. For more information on how we
                   gathered information for this study, see appendix I.



Results in Brief   The scientific community substantially agrees that black carbon aerosols
                   warm the atmosphere and cool the earth’s surface, while ozone contributes
                   to warming the earth, and sulfate aerosols contribute to cooling it,
                   according to the 2001 review, other scientific literature, and discussions
                   with atmospheric scientists. However, scientists are uncertain about the
                   extent of these effects. They believe that the level of uncertainty associated
                   with these pollutants is moderate for ozone and high for black carbon and
                   sulfate aerosols. While carbon dioxide and the other traditional greenhouse
                   gases generally contribute to temperature and other effects at a global
                   level, the three substances considered here operate on a different scale,
                   both in terms of time and geography. These three substances can have
                   effects over smaller distances and shorter time frames. In other words,
                   their impacts tend to be more important locally and regionally, while
                   having a smaller influence globally. Because of relatively rapid removal
                   from the atmosphere, their impact may be felt in the short-term, as
                   opposed to over decades or centuries hence. However, the effects of these
                   substances are not limited to warming; these substances may also cause
                   local cooling or may change local precipitation patterns. Since the 2001
                   review, other research has added to scientists’ understanding of the effects
                   of black carbon. For example, air and clouds over the Indian Ocean (which
                   are polluted with black carbon, sulfates, and other aerosols) were found to
                   absorb the sun’s energy to a far greater extent than expected. These results
                   suggest that black carbon, the only one of these substances that absorbs
                   rather than reflects light, may play a more important role in warming the
                   atmosphere than was estimated in the 2001 review.




                   Page 4                                 GAO-03-25 Air Pollutants and Climate Change
All seven countries are taking steps to reduce the amounts of the three
pollutants. In the United States and the other three economically developed
countries we studied, these efforts have been underway for decades. For
example, these countries limit emissions from power plants that burn
coal and other fossil fuels. They also regulate emissions from automobiles
and trucks. In these four countries, the amounts of the three substances
generally declined over the last 2 decades. For example, sulfur dioxide
emissions declined in all four countries and black carbon emissions
declined in three countries. Although sulfur dioxide emissions are
expected to decline in all of these countries, we found no emissions
projections for black carbon for three of them. Although developed
countries have made progress in reducing domestic ozone concentrations,
global ozone concentrations are likely to increase, owing to rising
emissions of ozone precursors in other countries. In contrast, in China
and the other two developing countries, emission control efforts are
more recent, typically going back only a decade or so. As in the developed
countries, these countries also target power plants and motor vehicles to
control emissions. In the developing countries, the levels of the three
substances varied. Sulfur dioxide emissions decreased in two countries,
but black carbon emissions increased in two countries. We found limited
information on ozone concentrations in developing countries. Most
available data pertain to only a few major cities and is not nationally
representative. Similarly, we were unable to find projections for sulfur
dioxide and black carbon emissions for these countries. The quality of data,
especially for developing countries, is uneven.

The results of empirical and theoretical research on the effect of
economic growth on environmental pollution are inconclusive. This
research has examined the hypothesis that pollution initially worsens as
an economy grows, but then improves as economic growth continues and
income rises. Empirical studies, which analyzed historical data to find
such a relationship across pollutants, have had mixed results. Similarly,
theoretical studies, which sought to identify how economic growth
may affect environmental pollution, have produced various possible
explanations but reached no consensus. Researchers agree that improved
data and more detailed studies will be needed to identify how economic
growth affects environmental pollution. Also, researchers caution that
economic growth does not automatically lead to reduced pollution. They
explain that, while economic growth may be necessary to provide the
resources needed to protect the environment, it is not, by itself, sufficient
to reverse environmental degradation and that appropriate environmental
policies must follow.



Page 5                                 GAO-03-25 Air Pollutants and Climate Change
Background   Although the sun heats the earth’s surface, a large fraction of the sun’s
             energy is reflected back into space by clouds, ground surfaces, ice, and
             water. However, certain gases in the earth’s atmosphere, such as carbon
             dioxide and methane, trap some of the sun’s heat and prevent it from
             returning to space. The trapped energy warms the earth’s climate, much
             like glass in a greenhouse. Hence the gases that cause this effect are often
             referred to as greenhouse gases.

             In response to potential environmental problems linked to the emissions
             of various heat-trapping gases, the United States and many other nations
             in 1992 signed a treaty aimed at limiting climate change induced by human
             activity. This treaty, called the United Nations Framework Convention on
             Climate Change, seeks to stabilize atmospheric concentrations of
             greenhouse gases at levels that would prevent dangerous human
             interference with the climate system. Under the 1992 convention, the
             United States and other parties generally agreed to implement programs
             aimed at reducing their emissions of greenhouse gases not covered by
             another treaty, the Montreal Protocol.4 The most important of these
             warming gases, in declining order, are carbon dioxide, methane, nitrous
             oxide, and three types of synthetic (manufactured) gases—sulfur
             hexafluoride, hydrofluorocarbons, and perfluorocarbons.




             4
               The Montreal Protocol, ratified by the United States in 1988, aims to reduce the
             use of substances that deplete stratospheric ozone. Among these substances are
             chlorofluorocarbons, which are also potent greenhouse gases.




             Page 6                                         GAO-03-25 Air Pollutants and Climate Change
In recent years, scientists have focused increased attention on the climatic
role of certain substances that are regarded as air pollutants (because of
their harmful effects on human health and the environment) but are not
covered by the Framework Convention or Montreal Protocol. These
substances are aerosols (including sulfate aerosols and black carbon) and
tropospheric ozone. Scientists have long recognized that these pollutants
can affect climate, but these pollutants were not included in the
Framework Convention. Sulfate and black carbon aerosols differ from
traditional greenhouse gases, such as carbon dioxide and methane, in two
key ways. First, unlike the traditional greenhouse gases, which are evenly
distributed throughout the atmosphere and have global impacts, the effects
of sulfate aerosols and black carbon are greatest near their sources,
although they can have global impacts. Second, whereas traditional
greenhouse gases can remain in the atmosphere for tens to hundreds, or
even thousands,5 of years, sulfate aerosols, black carbon, and ozone remain
in the atmosphere for much shorter time periods. Figure 1 shows the
sources and estimated mean atmospheric lifetimes of various substances
having an impact on climate.




5
  Sulfur hexafluoride and perfluorocarbons, which are man-made greenhouse gases, have
atmospheric lifetimes of several thousand years. They are not depicted in figure 1.




Page 7                                      GAO-03-25 Air Pollutants and Climate Change
Figure 1: Sources and Estimated Mean Atmospheric Lifetimes of Selected Substances Affecting Climate




                                                               3b
                                                                                                                               6      3b                                  2
                                                                                                                                2                     4
                                           4                                                                                           Coal Mine

                                4


                                                                                                                                                                                Power
                                                                                                                                                     2                          Plant
                                            3a                                       5                                                                    6
                                            3b
                                             6                                                                       3a
                                                 2                                                                                                                        3b
                                                                                                                        3b                                           2
                                                                                                                     6                                                    6
                                                                                                                    5




         County         4
         Landfill



        Substance                                    Major sources                                                                                            Mean atmospheric lifetime
   11. Sulfate aerosols                              Combustion of coal and oil (power plants)                                                                Days to weeks
   2    Black carbon                                 Incomplete combustion of fuels (diesel vehicles, forest fires, certain                                   Days to weeks
                                                     power plants, cook stoves)
   3    Tropospheric ozone                           Produced in the atmosphere by reactions, in the presence of sunlight                                     Days to weeks
                                                     involving nitrogen oxides and volatile organic compounds, including methane
                                                     and carbon monoxide
  3a        Nitrogen oxides                          By-product of combustion (vehicles, power plants)                                                        Days to weeks
  3b        Volatile organic compounds               Vehicles, industrial processes, trees                                                                    Days to weeks
   4    Methanea                                     Wetlands, cattle and other ruminant animals, fugitive emissions from coal mining, landfills              12 years
   53. Nitrous oxide                                 Agricultural soil management (application of fertilizers), vehicles                                      114 years
   64. Carbon dioxideb                               Combustion of carbon-containing substances, such as combustion of coal, oil, or                          50 to 200 years
                                                     natural gas in power plants or gasoline in vehicles; also from land-use changes


Source: Illustration prepared by GAO with portions using Art Explosion. For sources of information on lifetimes and sources, see next page.




                                                                       Page 8                                                                 GAO-03-25 Air Pollutants and Climate Change
a
Wetlands are a natural, as opposed to man-made, source of methane. We list them here because
wetlands are the largest single source of global methane emissions.
b
The lifetime of carbon dioxide depends on rates of absorption by oceans and vegetation.
Notes: For each substance, we depict only the most important sources. Additional sources of
emissions exist for most of the substances listed above.
This graphic was prepared by GAO with lifetime data reported in IPCC’s Third Assessment Report,
2001. Source data reported by EPA, National Air Quality and Trends Report, 1999; EPA, Inventory of
U.S. Greenhouse Gas Emissions 1990-2000; and Elaine Matthews, “Global Methane Emissions:
Historical Trends, Controlling Factors, and Future Prospects,” in Air Pollution as a Climate Forcing:
Workshop Proceedings, May 2002.


• Sulfate aerosols are created when sulfur dioxide emitted from, for
  example, coal- and oil-fired power plants, is oxidized in the atmosphere.
  Atmospheric sulfate aerosols have been associated with significant
  effects on public health and visibility impairment, and when they are
  deposited on earth, they contribute to the acidification of lakes, streams,
  and forests. Sulfate aerosol particles also have major effects on clouds,
  where they provide additional nuclei around which cloud droplets form.
  This can increase the cooling effect of clouds and may also increase the
  life spans of clouds. Both developed and developing countries burn coal
  to generate electricity, leading to emissions of sulfur dioxide.

• Black carbon, a type of aerosol, is a form of particulate matter and
  results from the incomplete combustion of coal, diesel fuel, and biofuels
  (such as alcohol or gasohol), and from open biomass burning, (i.e., the
  burning of forests and agricultural residues). Because it is dark in color,
  black carbon aerosol absorbs the sun’s energy, creating warming in the
  atmosphere and cooling at the earth’s surface, thus modifying climate
  (in contrast to the warming caused by traditional greenhouse gases,
  which prevent the earth’s heat from escaping into space). Black carbon
  is generally released with other pollutants in different proportions.




Page 9                                             GAO-03-25 Air Pollutants and Climate Change
• Tropospheric ozone is not emitted directly but is formed when
  emissions of other pollutants, called precursors, react in the presence
  of sunlight. Ozone precursors include nitrogen oxides (mainly nitric
  oxide and nitrogen dioxide) and several carbon-containing substances,
  namely carbon monoxide, methane, and non-methane volatile organic
  compounds. Nitrogen oxides are produced primarily by motor vehicles,
  other combustion engines, and electric power plants. Natural sources of
  nitrogen oxides are lightning and biological processes in soils. Carbon
  monoxide is formed when the carbon in fuels is not burned completely.
  It is a product of motor vehicle exhaust and industrial processes.
  Natural sources of carbon monoxide include wildfires. Methane is
  emitted by human activities, such as coal mining, natural gas and oil
  production, livestock production, rice cultivation, and waste disposal.
  It also comes from natural sources, including wetlands, and some
  animals, such as termites. Volatile organic compounds are produced by
  motor vehicles, industrial processes using solvents, and in some cases,
  by vegetation, including trees.6




6
  Isoprene and monoterpenes are examples of volatile organic compounds produced
by vegetation.




Page 10                                    GAO-03-25 Air Pollutants and Climate Change
In reviewing the scientific information on these three substances, we
concentrated on the material covered in the most recent systematic
published review, the IPCC’s Third Assessment Report, which represents
the consensus of many climate scientists.7 We also included some more
recently published material, notably the large-scale, multi-participant study
of aerosols over the Indian Ocean, known as the INDOEX study, which was
conducted in 1999. We included these results because they come from a
large, well-recognized, international program whose objectives overlap
substantially with many of the subject areas of this report.

The seven countries we reviewed differ greatly in terms of their
population, total area, and per capita income. For example, population
ranged from around 60 million in the United Kingdom8 to nearly 1.3 billion
in China; total area varied from just under 245,000 square kilometers for
the United Kingdom to 9.6 million square kilometers for the United States;
per capita income ranged from $2,200 in India to $36,300 in the United
States. See table 1.




7
    IPCC’s Third Assessment Report, 2001.
8
  The United Kingdom includes Great Britain (England, Scotland, and Wales) and
Northern Ireland.




Page 11                                     GAO-03-25 Air Pollutants and Climate Change
Table 1: Comparative Statistics of the Seven Countries Reviewed

                                                                             Estimated population                         Total area                 Per capita income,
Country                                                                        (2002) (in millions)              (square kilometers)                               2001
Economically developed countries
United States                                                                                  281.0                         9,629,091                             $36,300
United Kingdom                                                                                  60.0                           244,820                              24,700
Germany                                                                                         83.3                           357,021                              26,200
Japan                                                                                          127.0                           377,835                              27,200
Economically developing countries
China                                                                                       1,284.3                          9,596,960                                4,301
India                                                                                       1,045.8                          3,287,590                                2,200
Mexico                                                                                         103.4                         1,972,550                                9,000
Source: GAO (table), Central Intelligence Agency’s The World Fact Book, 2002 (data).

                                                                    Notes: Some figures have been rounded.
                                                                    Estimated gross domestic product per capita is based on purchasing power parity rates. Purchasing
                                                                    power parity asserts that a unit of currency, such as a dollar, should be able to buy the same bundle of
                                                                    goods in all countries.


                                                                    In the 1960s, scientists determined that emissions of sulfur dioxide from
                                                                    European power plants were causing the acidification of Scandinavian
                                                                    lakes. Recognizing that air pollution does not respect national boundaries,
                                                                    34 countries, including Germany, the United Kingdom, and the United
                                                                    States, signed the Convention on Long-Range Transboundary Air Pollution
                                                                    (CLRTAP) in 1979. Under a subsequent protocol to this convention, the
                                                                    signatories agreed to reduce their emissions of sulfur dioxide. Later, they
                                                                    extended the convention to further reduce sulfur dioxide and to reduce
                                                                    ozone precursors and various other pollutants.9 There are now 49 parties to
                                                                    the convention.

                                                                    In addition to commitments under this 1979 convention, several European
                                                                    countries, including Germany and the United Kingdom, are bound by
                                                                    European Union (EU) requirements to reduce emissions. For example, a
                                                                    1996 framework directive set broad goals for the consistent management of
                                                                    several air pollutants, including sulfur dioxide, nitrogen oxides, and ozone,
                                                                    in member nations. In 1999, a supplemental directive established a legally
                                                                    binding limit on concentrations of sulfur dioxide and nitrogen oxides,


                                                                    9
                                                                      The United States is party to some, but not all, of the CLRTAP protocols. Certain of the
                                                                    protocols extending the convention are not yet in force.




                                                                    Page 12                                             GAO-03-25 Air Pollutants and Climate Change
                          among other substances, to be achieved by all member countries by 2005.
                          Another 1999 directive required EU countries to reduce the sulfur content
                          of liquid fuel. (More information on the various directives can be found in
                          apps. II, III, and IV.) Each EU member nation is required to transform the
                          EU requirements into national legislation for domestic implementation. In
                          general, the EU emission reduction targets are more stringent than the
                          CLRTAP targets.



Scientists Agree on the   According to the most recent comprehensive review of scientific research
                          on climate change, published in 2001, scientists generally agree that sulfate
Overall Direction of      aerosols tend to cool the earth, while black carbon aerosols and ozone tend
the Three Pollutants’     to warm it. However, the extent of these effects is uncertain. Research
                          published since 2001 has not changed these overall conclusions, but it does
Climate Impacts,          suggest that the scientific community’s understanding of these effects is
but the Estimates         incomplete and needs further exploration.
of Impacts Contain
                          The extent of the heating and cooling effects of various substances, as
Significant               compared to pre-industrial conditions, is typically expressed in watts
Uncertainties             per square meter, which is a measure of energy per unit area. Changes in
                          the balance between incoming and outgoing solar energy in turn heat or
                          cool the earth. Specifically, the earth receives 342 watts per square meter
                          of incoming solar radiation annually at the top of the atmosphere and
                          reflects about 30 percent back into space, resulting in a net input of
                          240 watts per square meter. If the climate were in balance, the same
                          amount of energy that the earth received would be emitted back into space
                          as infrared radiation. However, warming gases trap some of this outgoing
                          radiation, thereby changing the balance between incoming and outgoing
                          radiation. Water vapor is the most significant greenhouse gas; carbon
                          dioxide is the second most significant. Additional carbon dioxide added to
                          the atmosphere by human beings since the industrial era has contributed
                          another 1.46 watts per square meter averaged over the earth’s surface
                          annually, thereby further warming the climate. Figure 2 shows how the
                          average effects of the three pollutants we reviewed compare with the
                          climate effects of carbon dioxide and other conventional greenhouse gases.




                          Page 13                               GAO-03-25 Air Pollutants and Climate Change
Figure 2: Direct Effects of Several Substances on Climate Change as Reported
in the IPCC’s Third Assessment Report, 2001

Watts per square meter                                                                                                       Warming effect
    1.8

    1.6
                         1.46
    1.4

    1.2

     1

    0.8

    0.6
                                     .48
    0.4
                                                                           .34               .35
    0.2                                                                                                                                .20
                                                       .15
     0

-0.2

-0.4                                                                                                               -.40

-0.6

-0.8
                                                                                                                               Cooling effect
     -1
                   ide




                                                                                        e



                                                                                                        ols
                                ne




                                                                 ga tic
                                                 e




                                                                                                                               sti l
                                                                                                                             bu ssi
                                                                                         n
                                                  id




                                                                       s




                                                                                                                                  on
                                                               se he




                                                                                      zo
                              tha
                  iox




                                                                    se




                                                                                                       ros
                                               ox




                                                                                                                         om fo
                                                             ou Synt




                                                                                  co
             nd




                           Me




                                                                                                                      l c om
                                                                                                   ae
                                           us




                                                                                 eri
                          a




                                          ro
            rbo




                                                         a,b




                                                                                                                   fue on fr
                                                                                                  te
                                                                                  h
                                      Nit




                                                                                                 lfa
                                                                               sp
          Ca




                                     a




                                                             nh




                                                                                             Su




                                                                                                                    arb
                                                                            po
      a




                                                                                             d
                                                            e



                                                                        Tro
                                                        gre




                                                                                                                 c
                                                                                                              ck
                                                                       c




                                                                                                             Bla
                                                                                                        d




          Legend
              High
              Best estimate
              Low
Source: Intergovernmental Panel on Climate Change, Third Assessment Report, 2001.

a
    Estimated uncertainties for these substances are plus or minus 10 percent.
b
    Synthetic gases include hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.
c
 Estimated uncertainty for ozone is plus or minus 43 percent.
d
 Please see notes below for a discussion of the uncertainty surrounding sulfate aerosol
and black carbon.
Notes: According to the IPCC, the level of scientific understanding is low for sulfate aerosol and very
low for black carbon aerosol. The uncertainty estimates in the report are a factor of 2 for each of these




Page 14                                                                               GAO-03-25 Air Pollutants and Climate Change
substances. (Factor of 2 means, for example, in the case of sulfate aerosol, the upper end of the range
would be -0.2, which is half the estimate—the estimate of 0.4 divided by factor of 2—and the lower end
of the range would be -0.8, which is twice the estimate—the estimate of 0.4 multiplied by factor of 2.)
Note that these uncertainty estimates are not based in statistics, but rather on the range found in the
recent literature.
Positive values indicate a warming effect; negative values indicate a cooling effect. The values for
black carbon include only the burning of fossil fuels, but not other sources, such as biomass burning,
which is estimated to make a similar-sized contribution to warming. Combustion of these substances
also emits organic carbon aerosols, which contribute an opposite (cooling) effect on climate. These are
all direct effects. Indirect effects, such as those operating through clouds, could increase the impacts of
both sulfates and black carbon. Note that these uncertainty estimates are not based on statistical
analysis, but rather are subjective judgments based on ranges found in reported studies. In addition,
the values for these estimates are described in the IPCC Third Assessment Report as having different
levels of scientific understanding associated with them: tropospheric ozone—medium; sulfate—low;
and fossil fuel black carbon—very low.


These three pollutants are relatively short-lived and are distributed only
locally or regionally, in contrast to the traditional greenhouse gases,
which persist for many years and are distributed worldwide. In
comparison, the effects of the short-lived substances must be averaged
over time and space.

Sulfate aerosols. According to the 2001 review, scientists generally agree
that sulfate aerosols contribute to cooling the earth. The uncertainty
regarding the climate effects of sulfate aerosols is significantly higher than
for tropospheric ozone. Because these aerosols are light colored, they do
not absorb sunlight. Consequently, their effect is purely cooling, because
they reflect sunlight back into space and prevent it from reaching the
earth’s surface. This cooling phenomenon is referred to as a direct effect on
the climate. The total amount of sulfate aerosols in the atmosphere is
estimated to be about 10 times larger than the total amount of black carbon
aerosols discussed below.

Scientists have also identified indirect cooling effects of sulfate aerosols
that result from their effect on clouds. Like some other aerosols, sulfates
become the nuclei onto which water vapor condenses, forming cloud
droplets. There, they produce clouds composed of larger number of smaller
droplets, which result in two indirect effects on the earth’s climate. First,
smaller droplets tend not to coalesce as readily into raindrops. Therefore,
clouds composed of smaller droplets are less likely to produce rainfall and
will persist longer. Since clouds scatter solar energy back out to space,
they redirect energy away from the earth, causing cooling. Second, since
smaller cloud droplets scatter more sunlight per mass than larger cloud
droplets, even more solar energy will be directed away from the earth.
Because of both the lessened rainfall from affected clouds and the changes
in local heating of the earth, with consequent reduction in evaporation,



Page 15                                               GAO-03-25 Air Pollutants and Climate Change
sulfate aerosols can reduce the amount and change the distribution of
rainfall in affected areas.

Black carbon. According to the 2001 review, scientists generally agree
that black carbon aerosols contribute to warming the atmosphere. As with
sulfate aerosols, the uncertainty associated with black carbon aerosols’
warming effect is high. Much of the uncertainty about black carbon
aerosols’ effects is due to questions about how these aerosols mix with
other types of aerosols and cloud droplets. In addition, black carbon is
released in association with other pollutants, such as organic carbon,
which has a cooling effect on climate. The proportions of each can differ
substantially among sources.

According to recently completed research on the effect of aerosols in
the atmosphere above the Indian Ocean,10 large amounts of aerosols—
including some black carbon—in the air masses coming off the Indian
subcontinent lead to dramatic reductions in the amount of solar radiation
reaching the ocean’s surface and may be reducing precipitation over
polluted areas. While these results appear to be significant for a particular
geographic area and time period, they have yet to be translated into
globally averaged contributions to warming the earth’s surface.
Nevertheless, they suggest that these aerosols may have a larger effect on
warming than was previously recognized.




10
 V. Ramanathan et al. “Aerosols, Climate, and the Hydrological Cycle.” Science, 294,
Dec. 7, 2001.




Page 16                                      GAO-03-25 Air Pollutants and Climate Change
Tropospheric ozone. According to the 2001 review, most scientists agree
that tropospheric ozone11 contributes to warming the earth. The level of
uncertainty associated with this warming effect is lower than the level for
sulfate aerosols and black carbon but is greater than for carbon dioxide
and other well-mixed greenhouse gases. However, ozone is not uniformly
distributed throughout the troposphere because it is produced in a very
uneven pattern in polluted areas and has a shorter lifetime than most other
greenhouse gases. As figure 2 shows, its estimated warming effect is about
one-quarter of the warming effect of carbon dioxide.

The formation of ozone in the atmosphere is complex. Most tropospheric
ozone is generated by gases, called ozone precursors, that are emitted by
industry, automobiles, and some natural sources, such as lightning and soil.
There are two main classes of ozone precursors: nitrogen oxides (made up
of nitric oxide and nitrogen dioxide) and certain carbon-containing gases,
such as carbon monoxide and volatile organic compounds, including
methane. Recent research suggests that reducing methane could have a
greater effect in reducing ozone than previously recognized.12,13 This
discovery is significant, since methane, unlike the other ozone precursors,
lasts in the atmosphere for as long as 10 years. (See fig. 1.)




11
  Ozone in the stratosphere also has impacts on climate. It is formed by different means
than ozone in the troposphere. We do not discuss stratospheric ozone at length in this report
because it is produced mainly through natural (non-human-induced) processes. Ozone in
the troposphere exists in two zones, the boundary layer and the free troposphere. The
significance of these zones is explained in the next section.
12
 Arlene Fiore et al. “Linking Air Pollution and Climate Change: The Case for Controlling
Methane.” Geophysical Research Letters, 29(19), 1919, 2002.
13
  Michael Prather et al. “Fresh Air in the 21st Century?” Geophysical Research Letters,
30(2), 1100, 2003.




Page 17                                       GAO-03-25 Air Pollutants and Climate Change
The Three Pollutants       The seven countries we reviewed have all enacted legislation and
                           implemented regulations to reduce emissions of sulfur dioxide14 and black
Are Generally              carbon, and concentrations of tropospheric ozone.15 For the most part, the
Declining in               levels of the three pollutants are declining in the four economically
                           developed countries and, to a limited extent, in the three economically
Economically               developing countries.
Developed Countries,
but Not in Developing      Our analysis of measures to control emissions and concentrations of
                           these substances is organized by pollutant; for each pollutant, we begin
Countries; All Seven       with the economically developed countries and then turn to the developing
Countries Are Acting       countries. Within the first group, we first discuss the United States because
to Reduce Emissions        we found the most complete information about it. We next discuss the
                           United Kingdom, Germany, and Japan, in declining order of available
                           information. For economically developing countries, for similar reasons,
                           the order is China, India, and Mexico.



Sulfur Dioxide Emissions   Of the three substances we reviewed, sulfur dioxide was the most widely
Declined in Nearly All     measured and regulated. Appendix II describes each country’s regulatory
                           approach to sulfur dioxide emissions in greater detail.
Countries; All Seven
Countries Are Taking
Steps to Reduce Them

Developed Countries        Sulfur dioxide emissions have declined and are expected to continue to
                           decline in the United States, United Kingdom, Germany, and Japan through
                           at least 2010, owing to a combination of explicit government policies
                           designed to curb sulfur dioxide emissions, the development of cleaner
                           power generation and transportation technologies, and a continuing
                           transition in many countries away from high-sulfur coal to low-sulfur
                           coal and natural gas. Figure 3 shows the decline in emissions for the
                           United States, the United Kingdom, and Germany between 1980 and 1999


                           14
                             In this report, we use sulfur dioxide emissions as a proxy for sulfate aerosols. This is
                           because sulfate aerosols are the result of the chemical transformation in the atmosphere
                           of sulfur dioxide emissions, such as those from power plants and other sources. It is
                           difficult to attribute sulfate aerosols in the atmosphere to individual countries, but such
                           attribution is possible with sulfur dioxide because many countries keep track of their sulfur
                           dioxide emissions.
                           15
                                Because ozone is not emitted directly, it is measured in terms of concentrations.




                           Page 18                                          GAO-03-25 Air Pollutants and Climate Change
and for Japan between 1990 and 1999, the only years for which we found
data for that country. As the figure shows, the greatest decline occurred in
Germany. In most of these countries, emissions declined more steeply
between 1990 and 1999 than between 1980 and 1990. Figure 4 shows
projected declines between 1990 and 2010 (1995 and 2010 for Japan). As
the figure indicates, the greatest relative decline is expected to occur
in Germany.



Figure 3: Sulfur Dioxide Emissions in Four Developed Countries, 1980-99

25,000 Thousand metric tonnes



20,000



15,000



10,000



 5,000



      0
           91
          80

          81
          82
          83
          84
          85
          86
          87
          88
          89
          90


          92

          93

          94

          95

          96

          97

          98

          99
        19
        19

        19
        19
        19
        19
        19
        19
        19
        19
        19
        19


        19

        19

        19

        19

        19

        19

        19

        19
          Year
       United States
       United Kingdom
       Germany
       Japan
Sources: GAO (graphic); data reported by governments to CLRTAP (U.S., U.K., and Germany) and data reported by the Japanese
government in Japan's Third National Communication to the UNFCCC, 2002.


Notes: A metric tonne is equivalent to 1.102 short tons (or 2,204 pounds). We were unable to locate
data from Japan for 1980 through 1989.




Page 19                                                        GAO-03-25 Air Pollutants and Climate Change
Figure 4: Projected Sulfur Dioxide Emissions in Four Developed Countries,
1990-2010

25,000 Thousand metric tonnes




20,000




15,000




10,000




 5,000




      0
                  1990                     1995                      1999                     2005                        2010
          Year
          United States
          United Kingdom
          Germany
          Japan
Sources: Prepared by GAO with data reported to CLRTAP (United States, United Kingdom, and Germany) and data provided by
Dr. T. Matsui, Japanese National Institute of Environmental Studies (Japan).

Notes: Projections of U.S. sulfur dioxide emissions do not include recent or proposed EPA rulemakings
that are likely to decrease sulfur dioxide emissions in the future. Values from 2000 to 2010 for the
United States, the United Kingdom, and Germany are based on 2010 projections.


Both the United States and European countries have health-based
standards designed to minimize damage to human health caused by sulfur
dioxide emissions. They also have annual emissions limits to control
acidification of the environment caused by these emissions. The United
States set its limits based on an across-the-board, 50-percent reduction in
sulfur dioxide emissions, relative to 1980, from power plants. In contrast,
the European governments set their standards using the “critical loads”



Page 20                                                        GAO-03-25 Air Pollutants and Climate Change
approach, taking into consideration the estimated potential impact of the
emissions on the environment. That is, the Europeans estimate, using
mathematical models, the maximum amount of damage that a particular
ecosystem—such as forests, lakes, and streams—could sustain before
long-term harmful effects occur. Standards aimed at reducing emissions to
a level near the critical load goal are then negotiated among countries. This
type of standard is often referred to as an effects-based standard. We were
unable to find information on how Japan developed its sulfur dioxide
emissions standards.

United States. U.S. emissions of sulfur dioxide decreased from
23.5 million metric tonnes to 17.1 million metric tonnes between 1980 and
1999, a decrease of about 27 percent, according to U.S. data submitted to
the CLRTAP. The United States projects that sulfur dioxide emissions will
decline even further, to 15.1 million metric tonnes in 2010, representing
about a 36-percent decrease from 1980 levels (See fig. 4.) The decline in
emissions in 2010 may be even greater because U.S. projections take into
account only national policies but not state regulations. They also do not
include proposed new measures.

Sulfur dioxide emissions started to decline in the United States in the early
1970s, after peaking at about 31 million tons. Federal regulation of sulfur
dioxide emissions essentially began with the Clean Air Act of 1970, as
amended in 1977 and 1990. The act required the Environmental Protection
Agency (EPA) to develop national air quality standards for air pollutants
that may endanger public health and welfare. EPA established such
standards for sulfur dioxide and several other pollutants. The act also
required each state to develop a plan (to be approved by EPA) for meeting
those standards. Under the act, all new or modified large power plants
could emit no more than a specified rate of sulfur dioxide per unit of fuel
consumed. Most new plants responded to this requirement by shifting to
coals with lower sulfur content.

Concern about sulfur dioxide emissions increased again in the late
1970s and early 1980s, when scientists noticed that lakes and streams,
particularly in the Northeast, were becoming increasingly acidic, thereby
threatening aquatic life. This acidity was traced to sulfur dioxide and
nitrogen oxide emissions from power plants, primarily those located
upwind in the Midwest. The 1990 Clean Air Act Amendments imposed
additional controls on such emissions. One of the programs created under
the amendments was the Acid Rain Program, which employs emissions
trading, a market-based mechanism, to reduce sulfur dioxide emissions.



Page 21                               GAO-03-25 Air Pollutants and Climate Change
United Kingdom. According to data submitted to the CLRTAP, the United
Kingdom reduced its sulfur dioxide emissions from just under 4.9 million
metric tonnes in 1980 to about 1.2 million metric tonnes in 1999, a decrease
of about 75 percent. The majority of the reduction was due to an increase in
the use of nuclear and renewable energy, fuel-switching (e.g., to natural
gas), improvements in efficiency, flue gas desulfurization,16 and fuel sulfur
reductions. The United Kingdom projects that its sulfur dioxide emissions
will decline even further, from about 1.2 million metric tonnes in 1999
to 0.6 million metric tonnes in 2010, an additional decrease of nearly
50 percent. If realized, this decrease would represent an 87-percent
reduction from the 1980 level.

Sulfur dioxide emissions, along with other pollutants, contributed to
several major smog episodes in London during the first 6 decades of the
20th century, with the most significant one occurring in December 1952.
That episode took more than 4,000 lives over 5 days. It also led to the
enactment of legislation in 1956 and 1968 that aimed to reduce emissions
from households. A 1990 law gave the government the power to set
emissions limits and environmental quality standards for industrial plants.
A 1995 law introduced a new framework for air quality policy, giving added
prominence to the concept of air quality standards.

In addition, the United Kingdom has international obligations to reduce
sulfur dioxide emissions. As a party to the CLRTAP, the United Kingdom
intends to reduce its annual emissions of sulfur dioxide by at least
80 percent by 2010 from its 1980 level. Furthermore, it must comply with
EU requirements to reduce sulfur dioxide emissions. (See app. II.)

Germany. According to data submitted under the CLRTAP, sulfur dioxide
emissions in the unified Germany declined by nearly 85 percent, from
5.3 million metric tonnes to 0.83 million metric tonnes between 1990 and
1999. This decline resulted from such factors as the post-1990 economic
restructuring, the retirement of outdated plants in the former East
Germany, and the use of less sulfur-intensive fuels. Germany reports that it
expects to reduce its sulfur dioxide emissions by about 34 percent between
1999 and 2010.




16
  Flue gas desulfurization equipment removes sulfur oxides from the combustion gases of a
boiler plant before it discharges them to the atmosphere.




Page 22                                     GAO-03-25 Air Pollutants and Climate Change
West Germany began to regulate sulfur dioxide in the late 1970s, when it
signed the CLRTAP. It participated in this effort in part out of concern that
sulfur dioxide-induced acidification was killing large numbers of trees in
the forests of southwestern Germany.

West Germany’s emissions of sulfur dioxide declined markedly during
the 1980s, mainly because utilities expanded their use of natural gas to
generate electricity, installed flue gas desulfurization technology in
power plants, and substituted less sulfur-intensive fuels at power plants
and in industry. In contrast, emissions in the former East Germany rose
until 1987, mainly because utilities there used lignite (low-grade coal) to
generate electricity.

Germany’s primary legislative instrument to control sulfur dioxide and
other air emissions is a 1974 law, amended in 2000, that regulates emissions
from both large and small combustion facilities. Supporting ordinances
contain detailed regulations and emissions limits for all facilities covered
by the act. Germany is also reducing its sulfur dioxide emissions under
both the CLRTAP and EU directives.

Japan. According to the Japanese government, sulfur dioxide emissions
declined by about 9 percent between 1990 and 1999, or from 0.97 million
metric tonnes to 0.87 million metric tonnes. According to another source—
a researcher from the Japanese government’s National Institute for
Environmental Studies—sulfur dioxide emissions may decline by
27 percent between 1995 and 2010.17

Compared with other industrialized countries, particularly the United
States and Germany, Japan uses considerably less coal, relying instead on
nuclear power to generate one-third of its electricity. Nevertheless, in 1968,
Japan began to regulate sulfur dioxide and other substances created by fuel
combustion. It set standards for emissions from power plants and factories
and provided for stations in several parts of the country to monitor
emissions of sulfur dioxide and other substances. In the late 1970s, the
government required facilities to install scrubbers in their smokestacks.
Japan also reduced its sulfur dioxide emissions through gains in
combustion efficiency and a transition to low-sulfur coal.


17
  Four scenarios with reductions ranging from 7 to 37 percent were prepared by
Dr. T. Matsui for the United Nations Environment Program. The data for Japan in figure 4
show projected emissions reductions in 2010 from an intermediate scenario.




Page 23                                      GAO-03-25 Air Pollutants and Climate Change
Developing Countries   As in the developed countries, China and Mexico saw an overall decrease
                       in sulfur dioxide emissions during the 1990s, as shown in figure 5. We were
                       unable to find data for India. Sulfur dioxide emissions in China declined by
                       15 percent between 1997 and 2000, in part as a result of the combination of
                       emission reduction policies and a decline in coal use. However, emissions
                       increased slightly after 1999. According to Mexico’s National Greenhouse
                       Gas Inventory, sulfur dioxide emissions decreased by about 55 percent
                       between 1990 and 1998, though they increased very slightly between 1993
                       and 1998. We were unable to find consistent historical data on sulfur
                       dioxide emissions in India. We were also unable to find data on projected
                       emissions levels for any of these three countries. According to U.S. experts,
                       the quality of some of the data for these countries is uncertain, due in part
                       to old measuring equipment and techniques.



                       Figure 5: Sulfur Dioxide Emissions in China and Mexico, Selected Years

                       25,000 Thousand metric tonnes



                       20,000



                       15,000



                       10,000



                        5,000



                             0
                                 1990       1991       1992       1993       1994       1995       1996          1997   1998   1999   2000
                                 year

                             China
                             Mexico
                       Sources: GAO (graphic); data reported by the Chinese State Environmental
                       Protection Administration and the Mexican National Greenhouse Gas Inventory, 1994-1998.



                       China. China is currently the world’s largest emitter of sulfur dioxide.
                       It relies heavily on coal as an energy source, and the country’s sulfur
                       dioxide emissions rose initially along with rapid industrialization. More
                       recently, according to the Chinese State Environmental Protection



                       Page 24                                                         GAO-03-25 Air Pollutants and Climate Change
Administration, emissions of sulfur dioxide declined from 23.4 million
metric tonnes to 20 million metric tonnes between 1997 and 2000.

Although under its current 5-year plan (2001-2005), China aims to reduce
coal consumption by increasing the share of natural gas and renewable
energy in the total energy supply, the U.S. Department of Energy’s Energy
Information Administration (EIA) projects that coal combustion in China
will increase 60 to 194 percent between 1999 and 2020, depending on
assumptions about economic growth. Thus, sulfur dioxide emissions could
also rise, unless implementation of a 1987 Air Pollution Control Law,
amended in 2001, can slow or reverse this trend. The law is designed to
improve air quality in large- and medium-sized cities through stiffer
penalties, better enforcement, and greater use of market-based methods,
such as the imposition of sulfur dioxide discharge fees. It also provides
incentives for using high quality, low sulfur coal and requires new or
expanded sulfur dioxide-emitting power plants and large- and medium-
sized enterprises to install sulfur dioxide scrubbing equipment.

India. We found limited data on India’s sulfur dioxide emissions.
Specifically, we found estimates from one source for 1980 and 1990,
which showed an 82-percent increase. We found an estimate from another
source for 2000 alone, which is higher than the 1990 estimate from the
other source. However, because these sources used different estimating
methods, their results may not be comparable.

We were also unable to find sulfur dioxide projections for India. However,
the EIA projects that India’s coal consumption will increase 9 to 62 percent
between 1999 and 2020, depending on assumptions about economic
growth. It also notes that, because of shortages in generating capacity and
public funds, India will probably continue to rely on old, coal-fired plants
for some time, despite their contribution to the country’s air quality
problems.

Coal accounts for more than half of India’s primary fuel consumption, but
the sulfur content of the coal used is relatively low. Nevertheless, India has
undertaken some steps to reduce sulfur dioxide emissions from coal. For
example, it has improved the combustion efficiency of conventional coal
technologies and has promoted the use of renewable energy technologies
as an alternative to coal. It further adopted national air quality standards
for sulfur dioxide and other pollutants in 1982 and revised them in 1994.
India has also reduced the sulfur content of oil products. According to the
EIA, India’s high levels of pollution do not result from a lack of effort in



Page 25                                GAO-03-25 Air Pollutants and Climate Change
building a sound system of legislation and regulation, but rather from weak
enforcement at the local level.

Mexico. According to the Mexican government, sulfur dioxide emissions
decreased by 67 percent between 1990 and 1992, but started to increase
gradually after 1992. Between 1990 and 1998, however, the net decrease
was 55 percent. We were unable to find data on projected sulfur dioxide
trends. However, Mexico has considerably expanded its use of natural gas,
which produces less sulfur than coal, and according to a 2002 report by the
EIA, most new power plants in Mexico are likely to be gas-fired, although
some new coal-fired plants will also be constructed. EIA projects that coal
consumption will grow 62 to 115 percent between 1999 and 2020,
depending on assumptions about economic growth. Most of Mexico’s
energy comes from oil, with coal providing only about 4 percent of the
country’s energy requirements.

The basic law for reducing air pollution emissions is the 1988 General
Law of Ecological Equilibrium and the Protection of the Environment.
The law provides the framework for air pollution standards for all major
substances. Environmental protection became a particularly important
issue for Mexico in the early 1990s as a result of negotiations for the
North American Free Trade Agreement with the United States and Canada.
In 1992, the Mexican government created a special office to enforce
regulations. This office is charged with inspecting facilities and issuing
penalties for noncompliance. According to Mexican government officials,
Mexico’s limited financial resources prevent full enforcement of
environmental regulations, despite steadily improving enforcement efforts.
Mexico has also introduced a federal tax incentive program for purchasers
of pollution control equipment. In addition to national legislation, some air
quality initiatives are underway in large cities, where urban air pollution is
a significant problem.




Page 26                                GAO-03-25 Air Pollutants and Climate Change
Black Carbon Emissions    Scientists have begun to recognize the importance of black carbon as an
Generally Declined in     agent of climate change only within the past few years. Consequently, most
                          countries do not directly track emissions of this pollutant. Therefore, to
Developed Countries and   conduct our analysis, we used a global black carbon database developed by
Generally Increased in    atmospheric researchers.18 This database has several limitations. First, as
Developing Countries      with most emissions inventories, estimates in this database are not based
                          on actual black carbon measurements, but rather are calculated using
                          information on countries’ use of fossil fuel, which is measured, along with
                          estimates of how the fuel is used. Second, this database does not contain
                          historical information on open biomass burning (forest burning or land-
                          clearing), which may account for as much as 50 percent of black carbon
                          emissions. Finally, emissions estimates are based on limited information
                          about the characteristics of the fuels and technologies that produce
                          the emissions.

                          Black carbon emissions are particularly difficult to track because they
                          are often produced by activities that are informal and unregulated,
                          and in developing countries, there is considerable consumption of
                          noncommercial fuels, such as wood or animal waste. Since these fuels are
                          not reported the same way as fossil fuels, neither the amounts used nor
                          the emissions produced are well quantified. Because sophisticated
                          emission measurements have usually been available only in developed
                          countries, moreover, there are few measurements of the combustion that
                          produces most black carbon emissions in developing countries. For these
                          and other reasons, the black carbon emissions data are highly uncertain.
                          Despite these weaknesses, this database is currently the only source we
                          found that contained consistently estimated information on different
                          countries’ emissions.




                          18
                            T.C. Bond and D.G. Streets, “Draft Global Black Carbon Inventory,” 2002. Dr. Tami Bond,
                          Visiting Scientist, National Center for Atmospheric Research, and Dr. David Streets, Senior
                          Scientist, Argonne National Laboratory, provided both data and commentary on this section.




                          Page 27                                      GAO-03-25 Air Pollutants and Climate Change
                      Black carbon usually comes from the same sources as organic carbon,
                      which has a cooling effect on climate. It would be difficult to control
                      emissions of either substance separately; hence, it would therefore be
                      difficult to control warming by reducing black carbon emissions. Although
                      countries do not regulate black carbon directly, it is one component of
                      what regulatory agencies often refer to as particulate matter,19 and most of
                      the countries we reviewed do regulate particulate matter. We therefore
                      collected information on measures to reduce particulate matter,
                      recognizing that this pollutant is an imperfect proxy for black carbon.
                      Furthermore, even when particulate matter emissions are reduced, black
                      carbon levels may not decline because some types of particulate matter,
                      such as sulfate, do not contain black carbon when emitted.

Developed Countries   According to the database we used, the majority of black carbon emissions
                      in developed countries results from the combustion of diesel fuel by
                      vehicles, including both on-road vehicles, such as heavy-duty trucks, and
                      off-road vehicles, including farm and construction equipment. As figure 6
                      shows, black carbon emissions from fossil fuel combustion declined in
                      three of the four developed countries, more in the United Kingdom and
                      Germany and less in the United States. During this period they increased in
                      Japan, starting in the early 1980s. (See app. III for more detail on policy
                      measures to reduce black carbon emissions.)




                      19
                        Particulate matter is the general term used for a mixture of solid particles and liquid
                      droplets found in the air. It comes from vehicle emissions, dust, fires, sea salt, and
                      black carbon (soot) from wood and coal burning. Particulate matter can be either coarse
                      or fine. Coarse particulate matter is referred to as PM10 because the particles have a
                      diameter of 10 micrometers or less. Fine particles, referred to as PM2.5, have a diameter of
                      2.5 micrometers or less. Black carbon is a component of PM2.5, but this fraction may vary
                      across countries, depending on fuel sources. Secondary particles can be formed in the
                      atmosphere from gaseous emissions. For example, sulfates are a form of particulate matter.




                      Page 28                                       GAO-03-25 Air Pollutants and Climate Change
Figure 6: Black Carbon Emissions in the United States, United Kingdom, Germany,
and Japan, 1980-96

500,000 Metric tonnes

450,000

400,000

350,000

300,000

250,000

200,000

150,000

100,000

 50,000

         0
                80

                81

                82

                83

                84

                85

                86

                87

                88

                89

                90

                91

                92

                93

                94

                95

                96
             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19

             19
             year

       United States
       United Kingdom
       Germany
       Japan
Source: GAO (graphic), T.C. Bond and D.G. Streets (data).

Note: Graphic based on global black carbon database prepared by T.C. Bond and D.G. Streets for an
article entitled, “A Technology-Based Global Inventory of Black and Organic Carbon Emissions from
Combustion,” to be submitted to the Journal of Geophysical Research.


United States. According to the database we examined, black carbon
emissions in the United States were approximately 4 percent lower in
1996 than in 1980. However, there was a steady increase from 1992 to 1996.
According to this database, about one-half of black carbon emissions in
the United States are from the use of diesel vehicles to transport goods
over long distances and from off-road diesel vehicles. However, the
database may not fully reflect the effects of certain technologies that
were introduced in the 1990s to reduce diesel emissions. Including such
technologies in the database would likely show greater emissions declines



Page 29                                                     GAO-03-25 Air Pollutants and Climate Change
during the 1990s. Gasoline-fueled cars and wood combustion in home
fireplaces and stoves are other, smaller sources of black carbon emissions.

The United States is the only country for which we found projections of
black carbon emissions. These were developed in support of an EPA
rulemaking20 relating to large trucks. When the rule is fully implemented in
2030, black carbon emissions are expected to decrease by an estimated
109,000 tons from the level produced in 1996.21

The United States has several efforts underway to help reduce emissions
of black carbon and other types of particulate matter. Under the Clean Air
Act, EPA promulgated national air quality standards for particulate matter
in 1971 and has regulated particulate matter emissions from highway motor
vehicle engines. The most recent rule is designed to reduce emissions from
heavy-duty diesel vehicles by improving diesel engines and reducing the
sulfur content of diesel fuel.22

United Kingdom. According to the database we used, black carbon
emissions from the United Kingdom declined by about one-third between
1980 and 1996. The sources of black carbon emissions in the United
Kingdom are similar to those in the United States, with the majority of
emissions produced by diesel vehicles. Other sources of black carbon
emissions are industrial coke-making23and coal-burning in the residential
sector, although residential coal use is declining in the United Kingdom.

The Parliament enacted legislation in 1956 and 1968 to control domestic
sources of particulate matter. The 1956 act aimed to control domestic
sources of smoke pollution by introducing smokeless zones (regions where
smokeless fuel had to be burned) and by making grants to homeowners to
convert their homes from traditional coal fires to heaters fueled by oil, gas,


20
   The 2002 Heavy-duty Diesel Engine Rule is aimed at reducing emissions from
heavy-duty trucks.
21
  EPA’s estimate of black carbon emissions for 1996 differs from that found in the Bond
and Streets database. This is because estimates from the two studies are based on different
assumptions.
22
  The sulfur content of diesel fuel is important because sulfur can impair the performance
of a vehicle’s emissions-reducing device.
23
   Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal.
It is used as a fuel (and as a reducing agent) for smelting iron ore in blast furnaces.




Page 30                                       GAO-03-25 Air Pollutants and Climate Change
smokeless coal, or electricity. Legislation in 1990 and 1995 brought many
smaller emission sources under air pollution control by local authorities for
the first time. These acts also provided a new statutory framework for local
air quality management. In 1997 the United Kingdom published its first
national air quality strategy, which set air quality standards and objectives
for the pollutants of greatest concern, including particulate matter. The
United Kingdom changed the particulate objective under this strategy in
2000, in response to a new EU directive and then in 2002 strengthened the
objective once more.

In the transportation sector, the EU in 1992 introduced directives
containing exhaust emission limits (generally referred to as the Euro I
standards) for new medium- and heavy-duty diesel engines. The standards
aimed to reduce emissions of particulate matter, as well as carbon
monoxide, hydrocarbons (including volatile organic compounds), and
nitrogen oxides, all ozone precursors. More stringent emission limits for
these vehicles, called Euro II, came into effect in 1996. Euro III limits were
adopted in 1999, and even more rigorous standards for these vehicles, Euro
IV and Euro V, are expected to take effect in 2005 and 2008, respectively.
The EU also set standards in 2001 for maximum allowable levels on the
sulfur content of diesel fuel. The directive, effective January 1, 2005, will
introduce sulfur-free diesel and gasoline in all EU member states.

Germany. Black carbon emissions in Germany also declined by about
one-third between 1980 and 1996, according to the Bond and Streets
database. While diesel consumption and emissions increased rapidly
during this time, a phase-out of coal combustion for home heating led to an
overall reduction in black carbon emissions. Other large sources of black
carbon emissions in Germany—much smaller than diesel vehicles—are
industrial coking coal and gasoline vehicles.

Between 1990 and 1996, Germany decreased its emissions of particulate
matter by 86 percent. The decrease occurred primarily because of
developments in eastern Germany after reunification, when many older
industrial and power plants were closed or refitted with new technologies
that remove soot particles. In addition, many installations shifted to the use
of gas and liquid fuels—especially in small combustion appliances—
thereby producing less particulate matter. The Federal Emission Control
Act provides the framework for regulating all air pollutants, and its
ordinances govern both large and small combustion facilities.




Page 31                                GAO-03-25 Air Pollutants and Climate Change
                       Like the United Kingdom, Germany must abide by EU directives aimed at
                       reducing particulate matter emissions, including the Euro I–III directives
                       on diesel vehicle emissions. Most diesel vehicles currently emit much less
                       particulate matter than earlier models, but Germany is continuing its effort
                       to reduce emissions in the transportation sector. For example, in 2001
                       Germany passed legislation to offer tax breaks for sulfur-free gasoline and
                       diesel fuel starting this year.

                       Japan. Black carbon emissions in Japan were about 60 percent higher in
                       1996 than in 1980, according to the database we used. The major source of
                       these emissions is diesel fuel, the use of which began to increase in 1988.
                       As in the United Kingdom and Germany, coke-making could be an
                       additional source of black carbon emissions in Japan.

                       In June 2001, Japan’s legislature enacted a law to further tighten particulate
                       matter emissions from diesel-powered vehicles to improve air quality in
                       major urban areas. The law applies to 196 local governments in Tokyo,
                       Osaka, and four other cities.

Developing Countries   The database we used indicates that black carbon emissions increased
                       between 1980 and 1996 in China and India, as figure 7 shows. It suggests
                       that Mexico’s black carbon emissions are essentially unchanged over
                       this period. We found no projections of black carbon for any of these
                       three developing countries.




                       Page 32                                GAO-03-25 Air Pollutants and Climate Change
Figure 7: Black Carbon Emissions in China, India, and Mexico, 1980-96

1,800,000 Metric tonnes

1,600,000

1,400,000

1,200,000

1,000,000

 800,000

 600,000

 400,000

 200,000

         0
                 80

                       81

                               82

                                83

                                           84

                                                 85

                                                        86

                                                              87

                                                                     88

                                                                           89

                                                                                 90

                                                                                       91

                                                                                             92

                                                                                                   93

                                                                                                         94

                                                                                                                 95

                                                                                                                  96
             19

                      19

                            19

                             19

                                        19

                                                19

                                                      19

                                                             19

                                                                   19

                                                                          19

                                                                                19

                                                                                      19

                                                                                            19

                                                                                                  19

                                                                                                        19

                                                                                                              19

                                                                                                               19
              year
         China
         India
         Mexico
Source: GAO (graphic), T.C. Bond and D.G. Streets (data).

Note: Graphic based on global black carbon database prepared by T.C. Bond and D.G. Streets for an
article entitled, “A Technology-Based Global Inventory of Black and Organic Carbon Emissions from
Combustion,” to be submitted to the Journal of Geophysical Research.


China. Emissions of black carbon in China rose by 43 percent between
1980 and 1996, according to the Bond and Streets database. Moreover,
according to that data source, China emits more black carbon than any
other nation in the world—approximately 29 percent of the global total.
However, its per capita emissions are not higher than those of other
countries. These emissions came primarily from coal (especially dirty
soft coal) and wood in the residential sector, coal-burning power plants
using older technologies, on-road and off-road diesel vehicles, and coke-
making plants in the industrial sector. Emissions increased steeply in the
1980s, but the growth rate slowed somewhat in the 1990s as China began to
switch from coal to cleaner natural gas and from raw coal to coal briquettes
(which produce fewer emissions) in the residential sector; it also closed
many small industrial coal plants.



Page 33                                                           GAO-03-25 Air Pollutants and Climate Change
Under amendments in 2000 to its Air Pollution Control Law, the
government set a goal of reducing “soot and flue dust” (particulate matter)
emissions to 1995 levels by 2010. According to the law, new or expanded
power plants and large- and medium-sized industrial facilities must install
particulate matter control equipment or take other measures to reduce
emissions. The city of Beijing requires the use of gas in place of coal in new
fuel applications.

In the transportation sector, China has implemented emissions standards
for diesel vehicles. In 2000 and 2001 the government introduced the Euro I
emissions standards for new cars and trucks. The standards, which apply
to the entire country, are based on those standards originally introduced in
Europe in 1992 and limit the amount the amount of particulate matter and
other substances that can be emitted from new diesel vehicles. More
stringent Euro II norms currently apply to Beijing and Shanghai and will
apply to the entire country after 2005.

India. According to the database we used, black carbon emissions in India
rose by just under one-third between 1980 and 1996. Most of this country’s
emissions come from the use of biofuel in the residential sector, with diesel
vehicles contributing a smaller, but noticeable, fraction. Black carbon
emissions increased between 1980 and 1996, as the population grew and
burned more wood, dung, and agricultural waste for cooking and home
heating.24 The Environmental Protection Act of 1982 set national standards
for the emissions of various substances. The standards were revised in
1994. Revisions to the act in 1996 set fuel quality specifications, including
requirements for low-sulfur diesel. In the capital city of New Delhi, 84,000
public vehicles were converted from gasoline and diesel to compressed
natural gas, which emits negligible particulate matter. In 2000, the Indian
government introduced Euro I standards for private, non-commercial
vehicles throughout the country. Euro II norms currently apply to
New Delhi and will apply to the entire country after 2010.

Mexico. Black carbon emissions in Mexico remained fairly constant
between 1980 and 1996, according to the database we used. Mexico is not
a large consumer of coal, instead relying primarily on oil as its key energy
source. Most of its black carbon emissions come from diesel fuel use.


24
  Levels of emissions from biofuels are particularly uncertain because data are so sparse.
Estimates in the Bond and Streets database are calculated based largely on a limited number
of fuel use surveys combined with socioeconomic data.




Page 34                                      GAO-03-25 Air Pollutants and Climate Change
                            However, according to a Mexican government official, in rural areas,
                            villagers burn propane or biomass for home cooking; biomass produces
                            black carbon emissions. Older gasoline cars also produce black carbon
                            emissions in Mexico.



Trends in Surface Ozone     The earth’s weather takes place in the lowest layer of the atmosphere,
Concentrations Are Mixed,   called the troposphere, which extends from the earth’s surface to between
                            9,000 and 16,000 meters above the surface. Within the troposphere, ozone
but Background Ozone
                            concentrations differ between zones,25 the boundary layer, which extends
Levels in the Troposphere   from the earth’s surface to roughly 500 to 3,000 meters above the earth’s
Appear to Be Rising, With   surface, and the much larger free troposphere. (The height of the boundary
Implications for both Air   layer can vary by time of day and season: higher in the daytime and in
Quality and Climate         summer, and lower in winter and at night.) Ozone in these two zones has
                            different durations and effects. There are important interactions between
                            the two zones.

                            Ozone in the boundary layer generally results from human activity, such
                            as transportation and fossil fuel combustion. Peak ozone episodes usually
                            occur in the summer months, under conditions of long periods of bright
                            sunshine, warm temperatures, light winds, and abundant ozone precursors.
                            Changing weather patterns contribute to yearly differences in ozone
                            concentrations from region to region.

                            Boundary layer ozone lasts only a few days over land, where it gets
                            deposited on surfaces. Over large bodies of water, such as oceans, it
                            can last longer, since there are no surfaces for deposition. At high
                            concentrations ozone can contribute to human respiratory problems and
                            plant damage.




                            25
                              Dr. Loretta J. Mickley, Research Associate, Atmospheric Chemistry, Division of
                            Engineering and Applied Sciences, Harvard University, and Dr. Michael Prather, Fred Kavli
                            Chair and Professor, Department of Earth System Science, University of California Irvine,
                            provided insights and comments on this section.




                            Page 35                                      GAO-03-25 Air Pollutants and Climate Change
The free troposphere is much larger than the boundary layer and extends
several miles above the boundary layer to the top of the troposphere.
Ozone in the free troposphere consists of some naturally occurring ozone
(such as ozone produced by lightning and ozone descending from the
stratosphere), as well as human-generated ozone carried upward from the
boundary layer by wind. Ozone in the free troposphere generally lasts
longer than ozone in the boundary layer—from 1 to several weeks.26 In the
free troposphere, ozone, like other greenhouse gases, can trap surface
radiation and contribute to warming the earth.

Air is exchanged extensively between the boundary layer and the free
troposphere. Consequently, ozone pollution arising from the boundary
layer—particularly in the northern hemisphere—has contributed to
increased levels of ozone in the free troposphere. Hence, the troposphere—
the source of clean air at the earth’s surface—is showing an increasing
background level of ozone.27 With the higher concentrations of ozone in the
free troposphere and in remote regions, more ozone can be blown into
populated areas, worsening the local pollution. Ozone pollution has also
been carried to the surface over remote regions, such as the oceans and
the Arctic.

Current estimates of ozone concentrations are based on profiles from
ozone balloons equipped with measuring devices (sondes). However, these
sondes are released from locations that are sparsely distributed around the
globe. Because the information from the sondes is so limited, we used two
types of proxy data to illustrate trends in the free troposphere, where
ozone can affect the climate. First, we used historical data on ozone at the
surface, which regulatory agencies, such as EPA, gather for air quality
purposes. These data are measured at a network of monitoring stations,
mainly in developed countries, and are collected primarily from urban and
suburban areas, where ozone is a major health concern. Second, we used
the results of a global modeling study that depicts ozone concentrations in
the free troposphere.

26
  Ozone has a shorter life span in the boundary layer because processes in that layer
can destroy ozone, but these same processes do not occur in the free troposphere.
The processes include deposition and chemical destruction at night.
27
  There are various definitions of background ozone. As used in this report, background
ozone refers to ozone that is produced by human sources as well as lesser amounts from
natural precursor sources—such as volatile organic compounds from vegetation or nitrogen
oxides from lightning—that travels into a given jurisdiction from elsewhere and is not
associated with local emissions.




Page 36                                       GAO-03-25 Air Pollutants and Climate Change
Some developed countries have prepared projections of ozone
concentrations at the surface, but because ozone projections prepared for
air quality purposes do not adequately represent ozone increases in the free
troposphere, where it is important for climate, we also used the results of a
modeling study from the Harvard University Atmospheric Chemistry
Modeling Group.28 These model results are based on an IPCC scenario that
assumes that in 2025 there will be high population growth; significant
income disparities between developed and developing countries; continued
dominance of fossil fuels, including coal, in developing countries; and some
policy measures in place to control ozone precursors. We used these
results to represent annually averaged ozone concentrations in the free
troposphere over the entire globe in 1990 and 2025. Unlike regional-scale
air quality models, such as those used by regulatory agencies, the Harvard
model is able to project ozone concentrations in the free troposphere and
at a global level, which is of greatest interest for climate change purposes.

Figure 8 shows calculated ozone concentrations at 5 kilometers
(about 3 miles) above sea level for 1990, while figure 9 shows projected
concentrations in 2025. Both maps are based on the Harvard model. A
comparison of the two maps indicates that free tropospheric ozone levels
are expected to increase over the next two decades. Increased emissions
of ozone precursors in Asia lead to higher ozone concentrations aloft,
with possible consequences for climate change.29




28
   We use projections prepared by Dr. L.J. Mickley of Harvard University’s Atmospheric
Chemistry Modeling Group. The Harvard model has been cited in the IPCC Third
Assessment Report, a peer-reviewed document. (The IPCC is the premier scientific
organization devoted to assessing climate change.) The projections were produced using a
general circulation (climate) model and depict expected global average ozone
concentrations in the free troposphere in 2025. For comparison purposes, we also include a
map showing tropospheric ozone concentrations in 1990. The Harvard projections are based
on the IPCC Special Report on Emissions Scenarios (IPCC/SRES) A2 Marker Scenario. The
Harvard model is able to capture in great detail the physical and chemical processes leading
to tropospheric ozone formation and can also show the long-range movement of ozone and
its precursors.
29
   Ozone levels are particularly low over most humid equatorial regions because, over the
humid tropics where nitrogen oxide emissions are generally low, water vapor is involved in
reactions that destroy ozone.




Page 37                                       GAO-03-25 Air Pollutants and Climate Change
The most significant of the precursors in this scenario is likely to be
methane,30 also a greenhouse gas, which is projected in the scenario to
increase globally by about 20 percent from its present level. Thus, methane
poses two problems: it can contribute directly to climate change as a
greenhouse gas, and it can indirectly contribute to climate change as an
ozone precursor.



Figure 8: Annually Averaged Global Ozone Concentrations at 5 Kilometers,
Parts per Billion, 1990


     1990




                Blue areas indicate low ozone concentrations

                Yellow and red areas indicate high ozone concentrations

Source: L.J. Mickley, Harvard University.




30
 Even though global emissions of methane appear to be slowing, it is not clear that they
will have dropped sufficiently to result in reduced concentrations in the atmosphere.




Page 38                                                    GAO-03-25 Air Pollutants and Climate Change
                      Figure 9: Projected Annually Averaged Global Ozone Concentrations at
                      5 Kilometers, Parts per Billion, 2025


                          2025




                                      Blue areas indicate low ozone concentrations

                                      Yellow and red areas indicate high ozone concentrations


                      Source: L.J. Mickley, Harvard University.




Developed Countries   Approaches to boundary layer ozone regulation in the United States
                      and Europe differ. The U.S. approach is almost exclusively health-based.
                      That is, its standards are designed to decrease prolonged human exposures
                      to ozone. By contrast, the European approach, as with sulfur dioxide
                      regulation, considers the cumulative effect of ozone concentrations on
                      human health and the environment. It seeks to reduce these concentrations
                      below those levels that affect public health and that can cause long-term
                      damage to the environment. Since the environment can be impaired at
                      lower concentrations than can human health, ozone concentrations
                      associated with European goals are lower than in the United States. While
                      the United States has firm air quality standards for ozone, the EU has
                      non-mandatory target values for ozone concentrations but mandatory
                      emission ceilings for ozone precursors, arrived at after a process that takes
                      both local ozone formation and transboundary transport into



                      Page 39                                                    GAO-03-25 Air Pollutants and Climate Change
consideration. Neither the United States nor most European countries
consistently meet their ozone standards in polluted areas. We were unable
to find information on how Japan sets its ozone standard.

Cumulative ozone levels in the boundary layer have generally risen over
the past century—particularly because of ozone produced in the northern
hemisphere. However, some developed countries, such as the United
States, the United Kingdom, and Germany, have reported fewer
exceedances of their ozone standards over the past decade. That is, peak
ozone episodes, in which boundary layer ozone concentrations rise
substantially above naturally occurring levels, are becoming somewhat
less frequent and extreme in many developed countries. The governments
attribute the improvement principally to policy measures over the past
decade or so. However, weather conditions and other factors can affect
year-to-year changes. Figure 10 shows that the number of locations
exceeding their respective ozone standards declined by nearly 70 percent
in the United States and by nearly 90 percent in Germany between 1990
and 2000. We were unable to find comparable data for the United Kingdom
and Japan. (More detailed information on ozone policies can be found in
app. IV.)




Page 40                              GAO-03-25 Air Pollutants and Climate Change
Figure 10: Number of Areas Exceeding the Ozone Standard, United States and
Germany, 1990-2000

120 Number of locations exceeding the standard


100


 80


 60


 40


 20


  0
        1990        1991       1992        1993       1994       1995       1996          1997   1998   1999   2000
      year
        United States
        Germany
Sources: GAO (graphic) data reported by the U.S. EPA and the German Environment Office.

Note: The U.S. ozone standard trend depicted here is 0.12 parts per million averaged over 1 hour. The
U.S. also has an 8-hour ozone standard. The German ozone standard tracked here is 0.055 parts per
million averaged over 8 hours.


United States. Under the Clean Air Act of 1970, EPA was charged with
developing air quality standards for air pollutants that may endanger public
health and welfare. EPA established such standards for ozone and nitrogen
oxides, an ozone precursor, in 1971. In 1979 EPA revised the ozone
standard to 0.12 parts per million daily maximum over a 1-hour period that
is not to be exceeded more than once per year on average. In 1997 EPA
tightened the standard to 0.08 parts per million averaged over 8 hours.
Although EPA has not yet begun to enforce the new 8-hour standard, it
does track concentrations in terms of this standard. According to EPA,
national ozone levels decreased 21 percent based on the 1-hour standard
and 10 percent based on the 8-hour standard between 1981 and 2000. For 52
metropolitan areas, the trend for 1-hour ozone levels improved between
1981 and 2000. However, beginning in 1994, the rate of improvement started
to level off, and the trend since then has been relatively flat.

The U.S. effort to control ozone has focused mainly on reducing emissions
of nitrogen oxides and volatile organic compounds, the two classes of
ozone precursors. The Clean Air Act requires each state with ozone


Page 41                                                        GAO-03-25 Air Pollutants and Climate Change
concentrations above the standard to develop a plan–known as a state
implementation plan—for reducing ozone formation; EPA must approve
this plan. This reduction can be attained through a mix of regulations in
various sectors, such as the utility, transportation, and industry sectors—
where most emissions occur. The ozone precursor methane is also
controlled under Clean Air Act regulations that require the combustion of
certain landfill gases from large landfills.

United Kingdom. According to United Kingdom government data, peak
ozone concentrations declined by 30 percent during the 1990s. Emissions
of nitrogen oxides declined by 42 percent between 1990 and 1999, while
emissions of volatile organic compounds, another ozone precursor,
declined by 34 percent between 1988 and 1999. The reductions in precursor
emissions are mainly due to stricter regulations, an increasing share of
vehicles fitted with catalytic converters (to control nitrogen oxides, volatile
organic compounds, and carbon monoxide), and reduced nitrogen oxide
emissions from power plants.

Incorporated into the United Kingdom’s framework for improving air
quality are several measures to address ozone formation. Many of these
measures were developed within the framework of the CLRTAP or the EU.
For example, in the transportation sector, implementation of the EU’s
Euro I standards limited emissions of the ozone precursors carbon
monoxide, hydrocarbons (including volatile organic compounds), and
nitrogen oxides from gasoline vehicles. More stringent standards came into
effect in 1997 and 1998, depending on vehicle type, and are known as
Euro II. These were superceded by Euro III standards for the majority of
vehicles in January 2001. A further tightening of the emissions limits,
referred to as Euro IV, will begin in January 2005 and will be fully in force
by January 2007.

Certain convention protocols also limit emissions of nitrogen oxides and
volatile organic compounds. The United Kingdom also has a domestic
target for ozone, which is more stringent than that of the EU.

Germany. According to the German government, peak ozone
concentrations have been declining since the mid-1990s. Between 1990 and
2000, emissions of nitrogen oxides declined by 40 percent, and emissions of
volatile organic compounds fell by 49 percent. The reductions were due
both to regulations—mainly in the transportation sector—and to economic
restructuring in the new states of eastern Germany.




Page 42                                GAO-03-25 Air Pollutants and Climate Change
                       Germany, like most other EU countries, has several measures in place for
                       reducing nitrogen oxides and volatile organic compounds, both ozone
                       precursors. These include emission-based motor vehicle taxes on heavy
                       utility vehicles and automobiles and requirements to install advanced
                       emissions reducing devices (that is, catalytic converters) on vehicles.
                       Measures in the utility and industry sectors will also increase the efficiency
                       of fuel combustion to reduce emissions of nitrogen oxides. Germany is
                       bound by the same EU directives and CLRTAP protocols as the United
                       Kingdom.

                       Japan. According to the Organization for Economic Cooperation and
                       Development, ozone concentrations have increased in urban areas by
                       about 5 percent since the late 1980s. However, according to Japanese data
                       submitted under the United Nations Framework Convention on Climate
                       Change, nitrogen oxide emissions increased by nearly 7 percent between
                       1990 and 1999, while emissions of volatile organic compounds decreased
                       by just over 3 percent.

                       In addition to its basic air quality framework, discussed earlier, Japan has
                       several laws targeted at reducing ozone precursors. The 1968 Air Pollution
                       Control Law established standards for photochemical oxidants (ozone) and
                       other substances, including the ozone precursors nitrogen dioxide and
                       carbon monoxide. In 1992 the government introduced the Automobile
                       Nitrogen Oxides Law to tighten controls on nitrogen oxide emissions from
                       vehicles in areas where improvements in emissions were difficult to realize
                       with existing measures. Among other things, the law regulates the types of
                       vehicles that can be driven in areas where nitrogen oxide emissions exceed
                       the environmental standard. The Japanese government has also set
                       emission standards for nitrogen oxides for each industrial facility. The
                       standards vary according to boiler type. Additionally, Japan’s air pollution
                       control law regulates volatile organic compound emissions from motor
                       vehicles.

Developing Countries   According to the World Health Organization, some of the poorest air
                       quality in the world, due in part to ozone pollution, is found in Beijing,
                       China; New Delhi, India; and Mexico City, Mexico. However, we were
                       unable to find national data on ozone concentrations for these three
                       countries. China and Mexico monitor ozone only in selected large
                       metropolitan areas. In Mexico City, ozone levels have declined
                       slightly since the early 1990s. We found no information on India. The IPCC
                       reported that emissions of nitrogen oxides—an ozone precursor—in East




                       Page 43                                GAO-03-25 Air Pollutants and Climate Change
                        Asia are increasing by about 4 percent per year. This suggests that ozone
                        levels may rise along with continuing industrialization in that region.

                        China. Vehicle emissions are one of the major sources of air pollution in
                        China’s major cities. The country currently has over 40 million vehicles,
                        and the number is growing by 10 percent annually; in large cities the rate
                        of growth is even higher. The Euro I vehicle emissions standards in place
                        around the country limit levels of carbon monoxide, hydrocarbons, and
                        nitrogen oxides. The Euro II standards, in place in Beijing, aim to further
                        reduce vehicle emissions in that metropolitan area.

                        Mexico. Efforts are underway to reduce emissions in the transportation
                        sector, particularly in Mexico City. Since 1993, the Mexican government has
                        increased its efforts to inspect motor vehicles. As of 2001, 230 new car
                        models had undergone emissions inspections. Another program reduces
                        the number of cars on the road in Mexico City and provides incentives for
                        the purchase of cars with lower emissions.

                        India. As in China, India’s Euro I and II performance standards for
                        automobiles are designed to help reduce emissions of key vehicle-related
                        ozone precursors.



Studies of the Effect   Both empirical and theoretical studies on the possible connection between
                        economic development and environmental quality are inconclusive overall.
of Economic Growth      Empirical studies, which analyze historical data for possible connections
on the Environment      between economic growth and environmental quality, have found that
                        emissions for some substances initially increase as national income rises
Are Inconclusive        and then decrease as a certain level of income is reached. However, these
                        results are not consistent across all studies and for all substances.31
                        Similarly, theoretical studies, which seek to understand the relationship
                        between economic growth and environmental quality, do not agree on the
                        major factors underlying this relationship. While acknowledging a probable
                        relationship between economic growth and environmental quality, the
                        authors of these studies caution that economic growth does not
                        automatically result in environmental improvement. They explain that,
                        while economic growth may enable countries to pay for environmental
                        protection, growth is not by itself sufficient to reverse environmental


                        31
                             Carbon dioxide is not regulated as a pollutant in the United States.




                        Page 44                                           GAO-03-25 Air Pollutants and Climate Change
                              degradation. See appendix V for more information on the studies
                              we reviewed.



Empirical Studies of the      The empirical studies we reviewed did not consistently find a relationship
Relationship between          that showed pollution initially increasing as per capita income increases
                              and then starting to decrease when income rises beyond a certain level.
Economic Growth and           However, such a relationship was found more often for some types of
Environmental Quality Yield   pollutants than others.
Mixed Results
                              If such a relationship between pollutants and economic growth is
                              presented graphically, it would form an “inverted U curve,” as shown in
                              figure 11. The point where the curve changes from an upward slope—
                              pollution increasing with income—to a downward slope is called the
                              “turning point.”



                              Figure 11: Hypothetical Inverted U-Shaped Curve, Showing Relationship Between
                              Per Capita Income and Environmental Pollution

                                                                 Turning point
                                  Environmental pollution




                                                                Per capita income
                              Source: GAO.




                              Page 45                                 GAO-03-25 Air Pollutants and Climate Change
In conducting these studies, researchers typically used various measures of
environmental quality, such as a specific pollutant or a composite measure
of environmental quality.32 In addition, to measure economic growth, the
studies commonly used per capita income, and in most cases, the income
levels were converted to 1985 U.S. dollars either by exchange rates or
purchasing power parity rates.33 The per capita income level for the United
States for 1985 was $16,410 under both the exchange rate and purchasing
power parity methods; for Japan, it was $10,900 for the former and $12,340
for the latter; for Mexico, $2,180 and $4,745; and for China, $280 and $785.

While overall the results of the studies are not consistent regarding an
“inverted U curve” relationship between pollution and economic growth,
they are more consistent in showing this relationship between pollutants
with localized and near-term effects, such as sulfur dioxide and particulate
matter. On the other hand, studies of substances with global and long-term
effects, such as carbon dioxide, sometimes did not find a turning point or
found a turning point beyond the income levels of the countries in
the study.




32
  The source for the environmental data most often used in these studies was the Global
Environmental Monitoring System, compiled by the United Nations, except for data on
carbon dioxide emissions from the U.S. Oak Ridge National Laboratory. Income data from
different countries were often adjusted to comparable units in terms of exchange rates or
purchasing power. In general, the data could be from as many as 149 economically
developing and developed countries for 1960 through 2000 or any year during that period.
Models differ in the exact specification of their equations, such as the number and type of
other factors that are included in the model (e.g., international trade, population density)
and the mathematical form of the relationship tested.
33
  To compare incomes across countries, incomes are converted to U.S. dollars in one of
two ways: (1) using the official exchange rate between the dollar and the other currency or
(2) using purchasing power parity rates—an international dollar that has the same
purchasing power in another country as the dollar has in the United States.




Page 46                                        GAO-03-25 Air Pollutants and Climate Change
For example, as shown in figure 12, the estimated turning point for sulfur
dioxide in the studies we reviewed using the purchasing power parity
method was typically in the range of $4,000 to $11,000.34 While these
estimated turning points were higher than per capita incomes in China and
Mexico, they were generally below the per capita incomes in Japan and the
United States in 1985. In addition, some estimated turning points for
particulate matter were in the range of $3,000 to $10,000, which is less than
per capita incomes in Japan, Mexico, and the United States. However, not
all the studies we reviewed found a turning point for pollutants with
localized effects. Specifically, one study found a turning point for sulfur
dioxide at a per capita income level far higher than any country’s level in
1985, and another study did not find a turning point for particulate matter.
The studies of carbon dioxide we reviewed either estimated a turning point
in the range of $10,000 to $63,000, which is above the per capita income
level of most countries, except for a few developed countries, or found that
there was no turning point (for example, because emissions and per capita
incomes increased together).




34
     All numbers are presented in 1985 dollars converted by purchasing power parity.




Page 47                                         GAO-03-25 Air Pollutants and Climate Change
Figure 12: Estimated Turning Points Found in Selected Studies of Particulate Matter,
Sulfur Dioxide, and Carbon Dioxide

120,000 Per capita income


100,000


 80,000


 60,000

 40,000


 20,000


       0




                                                      e
                                          ou




                                                                 -1




                                                                             -2
                     1




                               2




                                                                                        ik
                                                   se




                                                                                                n
                   e-




                             e-




                                                              en




                                                                          en




                                                                                              er
                                                                                     af
                                       ot



                                                 en
                  l




                              l




                                                                                   Sh
               Co




                           Co




                                                                                             St
                                                            ld




                                                                        ld
                                       y



                                               al
                                     na




                                                          Se




                                                                      Se
                                             hm
                                   Pa


                                           Sc


           Study

        PM
        SO2
        CO2
           United States
           Mexico
Source: GAO.

Note: Cole-1 and Cole–2 from Cole, Rayner, and Bates, “The Environmental Kuznets Curve: An
Empirical Analysis,” Environment and Development Economics (1997)—estimates from two models;
Panayotou from Panayotou, Sachs, and Peterson, “Developing Countries and the Control of Climate
Change: Empirical Evidence,” Discussion Paper #45, Harvard Institute for International Development
(1999); Schmalensee from Schmalensee, Stoker, and Judson, “World Carbon Dioxide Emissions:
1950-2050, “Review of Economics & Statistics (1998); Selden-1 and Selden-2 from Selden and Song,
“Environmental Quality and Development: Is There a Kuznets Curve for Air Pollution Emissions?,”
Journal of Environmental Economics and Management (1994)—two models estimated; Shafik from
Shafik, “Economic Development and Environmental Quality: An Econometric Analysis,” Oxford
Economic Papers (1994); Stern from Stern and Common, “Is There an Environmental Kuznets Curve
for Sulfur?,” Journal of Environmental Economics and Management (2001).




Page 48                                            GAO-03-25 Air Pollutants and Climate Change
                        Researchers suggested reasons an “inverted U” relationship is found more
                        often for sulfur dioxide and particulates than for carbon dioxide. For
                        example, they noted that the possible costs of climate change due to
                        increased carbon dioxide emissions are borne globally and by future
                        generations rather than locally and currently. Furthermore, the awareness
                        of the problem of climate change is more recent than the awareness of the
                        health effects associated with sulfur dioxide and particulates; policies to
                        control carbon dioxide emissions were generally not in effect during the
                        period of time analyzed by these studies.



Various Theoretical     Other studies have sought to understand the factors underlying the
Explanations Have       relationship between economic growth and environmental quality. These
                        studies generally agree that income is a proxy for a number of other
Been Suggested for      factors that may be influencing environmental quality as countries develop
the Relationship of     economically. These factors include, for example, changes in a country’s
Economic Growth and     economic structure, international trade, and a country’s preference for
Environmental Quality   environmental quality. Nevertheless, researchers do not agree on the
                        importance and role of any single factor. These three factors are
                        discussed below.

                        • Changes in a country’s economic structure. Some studies pointed
                          out that the relationship between economic growth and environmental
                          quality reflects changes in an economy’s structure as economies
                          develop and is not directly due to changes in income. Initially, these
                          studies note, economies are primarily agrarian and produce little
                          pollution. As these economies grow, the share of national output based
                          on agriculture decreases, while the share based on more pollution-
                          intensive manufacturing increases; hence pollution increases. At the
                          later stages of development, the share of national output based on
                          manufacturing decreases, while the share based on less
                          pollution-intensive services increases; hence, pollution decreases.




                        Page 49                               GAO-03-25 Air Pollutants and Climate Change
• The role of trade. Other studies noted that international trade can
  affect patterns of production and environmental quality. That is, trade
  allows economically developed countries to emphasize cleaner types
  of industries and to rely on imports from less-developed countries
  for goods produced by more polluting industries. As a result, the
  improvement in some developed countries’ environmental indicators is
  partly due to the contraction of their more polluting industries and the
  transfer of these industries to the less developed countries. However,
  researchers also observed that this process—and consequent
  improvement in environmental quality—cannot continue indefinitely
  because the relocation of polluting industries to other countries cannot
  continue indefinitely.35

• Preference for environmental improvement. According to still other
  studies, the relationship between economic growth and environmental
  quality reflects a country’s preference for environmental improvement.
  That is, environmental improvement could be described as a “luxury
  good,” that is, a good that people will seek more of as their incomes
  grow beyond subsistence level. Thus, in countries living at subsistence
  levels, pollution is accepted as a side effect of economic development,
  and people are not willing to reduce their consumption of basic
  necessities in order to set aside resources for environmental protection.
  However, as a country’s economy grows and incomes increase, people
  become more willing to divert a portion of their resources from current
  consumption to improve the environment. This economic growth, in
  turn, leads to stronger support for environmental legislation and new
  regulations to protect the environment.

Studies have also discussed other factors—-such as technology, population
density, political environment, and environmental regulations—that may
play key roles in shaping environmental quality as economies grow.
Regardless of their views, researchers generally agree that better data and
more detailed research are needed to conclusively identify the factors that
either directly, or indirectly through per capita income, influence
environmental quality.




35
  The empirical studies we reviewed that examined the role of trade on environmental
quality did not provide support for the suggestion that exporting polluting industries
(sometimes called “environmental dumping”) accounts for the observed reduction in some
pollutants in developed countries.




Page 50                                    GAO-03-25 Air Pollutants and Climate Change
Conclusions   Of the three substances we reviewed, sulfur dioxide emissions have
              received the most attention in the countries we examined. All of these
              countries have undertaken at least some measures to reduce sulfur dioxide
              emissions. Past trends and projections in all countries seem to be affected
              by economic growth and health concerns. The economically developed
              countries began this process much earlier—as far back as the 1970s or
              1980s—and they have been more successful thus far in realizing reductions
              than the three developing countries. In the developing countries, sulfur
              dioxide emissions declined (though in China and Mexico they have started
              to increase again), but they may decrease in the future if new policies are
              implemented and well enforced. While data on sulfur dioxide are far from
              complete, they are more readily available from country sources than
              data on the other two substances, particularly in developing countries.
              Since sulfate aerosol is a climate cooling agent, it is likely that reductions
              in sulfur dioxide emissions will result in some warming, at least at a
              regional level.

              Black carbon is being addressed indirectly through measures designed
              to reduce particulate matter in all of the developed countries and to a
              lesser extent in the developing countries. Emissions have begun to
              decline in developed countries, with the exception of Japan, according to
              the database we used, largely as a result of regulations limiting diesel
              fuel emissions, the major source of developed countries’ black carbon.
              Developing countries have not seen comparable declines in black carbon
              emissions, because home heating and cooking largely rely on burning coal
              and wood. Because small coal- or wood-burning stoves are widely used in
              these countries, black carbon emissions are more widely dispersed than,
              for example, sulfur dioxide emissions, which are usually associated with
              large power plants. Consequently, developing countries may find it
              challenging to control emissions of black carbon, at least for the
              foreseeable future. In addition, forest burning and land-clearing, major
              sources of black carbon emissions, are more prevalent in developing
              countries. Reliable measurements of black carbon from all seven countries
              are sparse.

              Tropospheric ozone levels are difficult to reduce because they result from
              emissions of precursor substances produced by a very diverse range of
              sources. Nevertheless, developed countries have had some success over
              the past decade in reducing high ozone levels, particularly in major urban
              and suburban areas. This trend is likely to continue over the next two
              decades, but ozone concentrations in developing countries may continue to



              Page 51                                GAO-03-25 Air Pollutants and Climate Change
                  rise along with industrialization for the foreseeable future. The developing
                  countries we analyzed are only starting to take measures to reduce ozone
                  and its precursor substances. Consequently, ozone levels in the free
                  troposphere are likely to increase globally as a result of a net increase in
                  emissions of its precursors at the surface. Methane is expected to play a
                  particularly important role in the formation of ozone in the future.

                  The results of economic research do not convincingly establish whether
                  a country’s environmental pollution initially increases and then, with
                  economic growth, decreases. This type of relationship seems to apply to
                  some types of pollutants but not to others. Researchers generally agree,
                  however, that unless the incentives facing producers and consumers
                  change with higher incomes, pollution will continue to increase as
                  economies grow. In other words, income growth, while a necessary
                  condition, is not sufficient to reverse environmental degradation.
                  Environmental policies must follow to induce appropriate responses and
                  turn the pollution path around.



Agency Comments   We provided a draft of this report to the Secretary of Energy and the
                  Administrator of EPA for review and comment. The agencies provided
                  written clarifying comments, which we incorporated where appropriate.

                  As arranged with your offices, we plan no further distribution of this report
                  for 30 days after the date of this letter, unless you publicly announce its
                  contents earlier. At that time, we will send copies of this report to the
                  Ranking Minority Members of the Committee on Energy and Commerce,
                  House of Representatives, and its Subcommittees on Energy and Air
                  Quality and Oversight and Investigations; the Secretary of Energy; the
                  Administrators of the Environmental Protection Agency, National
                  Aeronautics and Space Administration, and National Oceanic and
                  Atmospheric Administration; the Director, National Science Foundation;
                  the Director, Climate Change Science Program Office; and other interested
                  parties. We will make copies available to others upon request. In addition,
                  copies of this report are available at no cost at our Web site, www.gao.gov.




                  Page 52                               GAO-03-25 Air Pollutants and Climate Change
If you have any questions about this report, please contact me at
(202) 512-3841. Key contributors to this report are listed in appendix VI.




John B. Stephenson
Director, Natural Resources
 and Environment




Page 53                               GAO-03-25 Air Pollutants and Climate Change
Appendix I

Scope and Methodology                                                                                     AA
                                                                                                           ppp
                                                                                                             ep
                                                                                                              ned
                                                                                                                n
                                                                                                                x
                                                                                                                id
                                                                                                                 e
                                                                                                                 x
                                                                                                                 Iis




             To obtain information on recent research relating to the climate
             change characteristics of the three substances, we contacted scientists in
             four federal agencies: the Department of Commerce’s National Oceanic
             and Atmospheric Administration; the Department of Energy; the
             National Aeronautics and Space Administration; and the National
             Science Foundation. These scientists were recommended by staff at
             the U.S. Climate Change Science Program, an interagency research
             coordinating body.

             In analyzing trends for the three pollutants, we found that the availability
             and quality of data varied considerably, especially in developing countries.
             Except for countries that are members of the EU or participate in the
             CLRTAP, governments are not required to report their emissions of
             these substances internationally.1 We found no standardized system for
             calculating and reporting emissions. Moreover, some of the data reported
             here are based on direct measurements, while others are estimated using
             proxy data (such as fuel use information), which may be less exact than
             measured data. Most of the data used in this study, except where noted, are
             taken from government sources. Dr. Tami Bond of the National Center for
             Atmospheric Research; Dr. Loretta Mickley of Harvard University;
             Dr. Michael Prather of the University of California, Irvine; and Dr. David
             Streets of Argonne National Laboratory provided comments and insights
             on certain sections of the report. The information on foreign countries’
             emissions levels and legislation does not reflect our independent analysis.

             To obtain information on policies and measures, we first sought a
             comprehensive source of information for each country. Because we
             found no such source, we contacted government, academic, and other
             researchers and analysts in the United States and the other countries, and
             the countries’ embassies in the United States. We also gathered information
             from government publications, web sites, e-mail correspondence with
             U.S. and foreign government officials, and discussions with embassy
             personnel. While we tried to make this report as complete as possible,
             there may be additional policies and programs underway that are not
             addressed here.




             1
               Under the Framework Convention on Climate Change, developed (Annex I)
             countries generally report their emissions of sulfur dioxide along with their emissions of
             the six conventional greenhouse gases. This is the source of our data on Japanese sulfur
             dioxide emissions.




             Page 54                                       GAO-03-25 Air Pollutants and Climate Change
Appendix I
Scope and Methodology




To assess the literature on the relationship between economic growth and
environmental pollution, we conducted computerized literature searches
to identify relevant articles. To help us determine which articles to focus
on, we sought guidance from recognized experts who specialize in this
field. The extent of governmental action to control a specific pollutant is
believed to be one important factor—but not the only factor—in explaining
the relationship between economic growth and emissions of that pollutant.
Therefore, even though few countries have acted to control carbon dioxide
emissions and have done so recently, we included studies that examined
the relationship between economic growth and such emissions.

We conducted our review between October 2001 and April 2003 in
accordance with generally accepted government auditing standards.




Page 55                              GAO-03-25 Air Pollutants and Climate Change
Appendix II

Programs and Measures to Reduce Emissions
of Sulfur Dioxide                                                                                                               Appendx
                                                                                                                                      Ii




Country          Measures
United States    Section 109 of the Clean Air Act requires EPA to establish National Ambient Air Quality Standards
                 (NAAQS) for air pollutants that may endanger public health and welfare. EPA established such NAAQS
                 for sulfur dioxide. Under the 1990 amendments, areas not in attainment with the NAAQS must meet
                 special compliance schedules.
                 Section 110 of the Clean Air Act requires states to adopt plans, known as State Implementation Plans
                 (SIP), which detail the regulations a state will use to implement, maintain, and enforce the NAAQS. EPA
                 must approve each SIP, and if a SIP is not acceptable, EPA may take over enforcement of the Clean Air
                 Act in that state.
                 Section 111 of the Clean Air Act requires EPA to establish nationally uniform, technology-based
                 standards called New Source Performance Standards for categories of new industrial facilities, such as
                 power plants, steel mills, and smelters. These standards limit the amount of certain pollutants, including
                 sulfur dioxide, that may be emitted.
                 Sections 160-169 of the Clean Air Act establish requirements for the prevention of significant
                 deterioration (PSD) of air quality in areas that have attained the NAAQS. The act divides clean air areas
                 into three classes and specifies the increments of sulfur dioxide and particulate matter pollution allowed
                 in each. In order to receive a PSD permit, a new or modified major source of pollution must show that it
                 will not contribute to a violation of the increments or of the national ambient air quality standards and
                 that it will use best available control technology (BACT). This provision is referred to as PSD New
                 Source Review.
                 Sections 171-173 of the Clean Air Act establish pre-construction permitting requirements for major new
                 and modified sources in non-attainment areas (areas that have not attained the NAAQS). To receive a
                 permit, such sources must, among other things, (1) obtain emissions offsets, thereby assuring that
                 reasonable progress toward attainment of the NAAQS will occur, and (2) comply with the “lowest
                 achievable emissions rate.”
                 Title IV of the Clean Air Act created EPA’s Acid Rain Program, which caps sulfur dioxide emissions from
                 virtually all U.S. electric power plants at 8.95 million tons. Plant operators were required to reduce their
                 emissions through any combination of strategies, including installing scrubbers, switching to natural gas
                 or low-sulfur coal, or trading emissions allowances. The first phase of the program ran from 1995 to
                 1999, and the second phase, with more stringent caps, began in 2000 and will run indefinitely. The
                 program features a provision that allows power plants that exceed their emissions targets to “bank”
                 extra allowances during the first phase of the program and then use these banked allowances during
                 the more stringent second phase.
United Kingdom   The United Kingdom’s 1956 and 1968 Clean Air Acts, among other things:
                 • authorized local councils to set up smokeless zones and make grants to householders to convert their
                   homes from traditional coal fires to heaters fueled by gas, oil, smokeless coal, or electricity.
                 • set limits on sulfur dioxide emissions from small power plants.
                 • The United Kingdom’s Environment Act of 1995 requires the government to produce a national air
                   quality strategy that identifies clear, measurable targets for improved air quality in the United Kingdom.
                   This strategy is to be developed based on understanding of the health effects of the pollutants
                   concerned and costs of emission reduction methods and aims to improve air quality by 2005. The
                   strategy sets standards and objectives for sulfur dioxide and seven other air pollutants. The 1995 act
                   also established a system of local air quality management, under which authorities are required to
                   assess the current and future quality of air in their areas against the national air quality strategy
                   objectives.




                               Page 56                                         GAO-03-25 Air Pollutants and Climate Change
                                               Appendix II
                                               Programs and Measures to Reduce Emissions
                                               of Sulfur Dioxide




(Continued From Previous Page)
Country                          Measures
                                 The Convention on Long-Range Transboundary Air Pollution (CLRTAP) binds the United Kingdom to
                                 reduce sulfur, as do certain CLRTAP protocols:
                                 • The 1994 Oslo Protocol on Further Reduction of Sulfur Emissions, which aims at gradually achieving
                                   critical loads of sulfur.
                                 • The 1999 Gothenburg Protocol, signed but not ratified by the United Kingdom, which set emissions
                                   ceilings for 2010 for sulfur dioxide and three other pollutants, is expected to enter into force as early as
                                   2003. (CLRTAP covers more European countries than the EU, but the EU directives generally require
                                   more ambitious emissions reductions than the CLRTAP protocol.)
                                 EU directives which require the United Kingdom to reduce sulfur dioxide emissions include:
                                 • The First Daughter Directive (1999/30/EC), under which EU members must establish, and achieve by
                                   2005, a legally binding limit on concentrations of sulfur dioxide and three other substances.
                                 • The Directive on the Incineration of Wastes (2000/76/EC), which sets limits on emissions of sulfur
                                   dioxide and other substances from waste incineration plants.
                                 • The Large Combustion Plant Directive (2001/80/EC), which sets limits on sulfur dioxide and nitrogen
                                   oxides from combustion plants with a thermal input of 50 megawatts or greater.
Germany                          • The Large Combustion Ordinance contains emissions ceilings for new power plants in Germany.
                                 • The CLRTAP requirements and EU directives also apply to Germany.
China                            The Air Pollution Control Law, enacted in 1987 and amended in 2000, aims to improve air quality in key
                                 urban areas. Specifically, it
                                 • broadens the scope of affected industries beyond industrial sources and power plants, to include
                                   automobiles, ships, domestic heating, and cooking stoves;
                                 • provides an incentive for using high-quality, low-sulfur coal and renewable energy;
                                 • allows so-called “priority cities” to designate zones within which all burning of high-polluting fuel (i.e.,
                                   coal) can be prohibited and calls for the phase-out of a form of dirty coal in large- and medium-sized
                                   cities;
                                 • requires new or expanded sulfur dioxide-emitting power plants or large- and medium-sized industrial
                                   enterprises to install desulfurization equipment; and
                                 • encourages cities to replace individual household coal heating stoves with centralized district heat.
                                 The Energy Conservation Law, which entered into force in January 1998, promotes energy conservation
                                 and efficiency. Other energy conservation laws also exist.
                                 A fuel tax has been imposed on high-sulfur coals, and between January and September 2000, 4,732
                                 mines producing high-sulfur coal were closed.
                                 Subsidies for coal have been greatly reduced since 1984.
Source: GAO.




                                               Page 57                                          GAO-03-25 Air Pollutants and Climate Change
Appendix III

Programs and Measures to Reduce Emissions
of Black Carbon or Particulate Matter                                                                                                   Appendx
                                                                                                                                              iI




Country          Measures
United States    The Heavy Duty Diesel Rule, promulgated in 2001, will require significant future reductions in highway diesel
                 engine particulate matter emissions. It will also require diesel oil refiners to reduce most sulfur from diesel fuel
                 by 2006 in preparation for new engines in 2007. In 2030, when the rule is fully implemented, it is expected that
                 particulate matter from diesel vehicles will be reduced by 130,000-140,000 tons per year relative to 1996.

United Kingdom   The Smoke Control Act of 1993 empowers local authorities to declare a smoke control area if it appears that
                 air quality standards will not be met. Under the law, the local government can require that only certain fuels be
                 used for domestic heating.
                 EU directives aimed at reducing particulate matter include:
                 • Directive 1998/70/EC, which sets the maximum allowable sulfur content of gasoline and diesel fuel.
                 • The First Daughter Directive (1999/30/EC), which contains a particulate matter standard for the EU
                   countries.
                 • The Directive on the Sulfur Content of Certain Liquid Fuels (1999/32/EC), which mandates reductions in
                   sulfur content of diesel fuel to enhance performance of emissions-reduction devices.
                 • Directive 1999/96/EC, which sets the emission limit values and implementation dates in two stages for heavy
                   duty vehicles (Euro III and IV). The standards cover emissions of particulate matter and ozone precursors.
Germany          The EU directives described above also apply to Germany.
China            Euro I and II standards for the control of emissions from diesel vehicles.
India            Euro I and II standards for the control of emissions from diesel vehicles.
Source: GAO.




                                      Page 58                                          GAO-03-25 Air Pollutants and Climate Change
Appendix IV

Programs and Measures to Reduce
Ground-Level Ozone                                                                                                                    Appendx
                                                                                                                                            iIV




Country          Measures
United States    The Clean Air Act has resulted in the creation of several trading programs for reducing nitrogen oxide
                 emissions in the electric utility sector:
                 • EPA’s Acid Rain Program sets emissions rates for all affected utilities. Unlike sulfur dioxide, there is no cap
                   on total nitrogen oxide emissions, but utilities may choose to over-control at units where it is easier to do so
                   and average these emissions with those at their other units, thereby achieving overall emissions reductions
                   at lower costs.
                 • The EPA Nitrogen Oxides SIP Calla requires 19 states and the District of Columbia to reduce total nitrogen
                   oxide emissions from utilities by a certain number of tons each year; compliance for Phase I must be
                   achieved no later than May 31, 2004. Power producers subject to these regulations are allowed to trade
                   emissions allowances to meet the required limits.
                 • The Nitrogen Oxides Budget Trading Program, begun in 1999 in nine Northeastern states, aims to reduce
                   nitrogen oxide emissions during the summer months to enable states to attain the standard for ground-level
                   ozone. Like the programs above, it is a cap and trade program, under which total emissions are capped, and
                   affected parties may trade emissions allowances.
                 The Clean Air Act has also provided the framework for ozone-reducing reductions in the transportation sector.
                 The most recent regulation with significant impact on transportation sector ozone precursors is the Tier 2
                 program, which was promulgated in 2000 and will be phased in starting in 2004, when refiners must produce
                 low-sulfur fuel for passenger vehicle gasoline. Tier 2 also sets tailpipe emission standards for all classes of
                 passenger vehicles, including sport utility vehicles and light-duty trucks.
                 A Clean Air Act regulation requires the combustion of methane and other non-methane organic compounds
                 from large landfills. The regulation also contains a performance standard based on the allowable
                 concentration of methane measured at the landfill.
                 In addition to programs regulating emissions from cars and trucks, EPA regulates emissions of nitrogen oxides
                 and hydrocarbons from aircraft, ships, locomotives, recreational vehicles, off-road diesel equipment (e.g., farm
                 and construction equipment), and spark-ignition engines, such as chain saws, lawn mowers, and forklifts.
                 The U.S. Department of Transportation administers a program called “Congestion Mitigation and Air Quality
                 Improvement” aimed at reducing ozone and its precursors (as well as particulate matter) by funding new
                 transit services, bicycle, and pedestrian improvement, alternative fuel projects, traffic-flow improvements, and
                 other emissions-reducing projects.
                 In the industrial sector, the Clean Air Act specifies performance standards for new industrial sources.
                 The standards, called New Source Performance Standards, establish maximum emission levels for new
                 or modified major stationary sources, such as steel mills and smelters. These standards also apply to
                 power plants.
United Kingdom   CLRTAP Protocols that bind the United Kingdom and other European countries include:
                 • The 1988 Sofia Protocol, which set a target for emissions of nitrogen oxides.
                 • The 1991 Geneva Protocol, which requires a reduction in emissions of volatile organic compounds.
                 • The 1999 Gothenburg Protocol, signed but not ratified by the United Kingdom, which sets emissions ceilings
                   for nitrogen oxides, volatile organic compounds, and two other substances.




                                      Page 59                                        GAO-03-25 Air Pollutants and Climate Change
                                    Appendix IV
                                    Programs and Measures to Reduce
                                    Ground-Level Ozone




Country        Measures
               The EU directives aimed at reducing ozone and/or its precursors include:
               • Directives on Air Pollution by Ozone (92/72/EC and 2002/3/EC), which establish thresholds for ozone and
                 require that threshold exceedances must be reported to the EU Commission and to the public.
               • The Directive on VOC Emissions from the Storage of Petrol (94/63/EC), which sets guidelines for reducing
                 volatile organic compound emissions from the storage and distribution of petrol (gasoline) from terminals to
                 service stations.
               • The Framework Directive (96/62/EC), which established the framework under which the EU countries would
                 agree on emissions limits for certain pollutants. The Directive requires that, if limits are exceeded, member
                 states devise abatement programs to reach the limits within a set deadline.
               • The Directive 98/69/EC, which establishes emission limit values and implementation dates in two stages for
                 light-duty vehicles (Euro III and IV). The standards cover ozone precursors and particulate matter.
               • The First Daughter Directive (99/30/EC), which sets limit values for nitrogen oxides (and other substances.)
               • The VOC Solvents Directive (99/13/EC), which limits emissions of volatile organic compounds.
               • The Directive on Landfills (99/31/EC), which aims to harmonize controls on the landfill of waste throughout
                 the EU. Its main focus is on common standards for the design, operation and aftercare of landfill sites. It also
                 aims to reduce the amount of methane emitted from landfill sites.
               • The Large Combustion Plant Directive (2001/80/EC), which sets limits on sulfur dioxide and nitrogen oxides
                 from combustion plants with a thermal input of 50 megawatts or greater.
               The National Emission Ceiling Directive (2001/81/EC), which sets ceilings for emissions of nitrogen oxides,
               sulfur dioxide, ammonia, and volatile organic compounds to be attained by 2010. (As of early 2003, this
               protocol was not yet in force.)
Germany        The CLRTAP requirements and EU directives cited above apply to Germany.
Japan          The Air Pollution Control Law requires stations in several parts of the country to monitor for nitrogen dioxide,
               suspended particulate matter, sulfur dioxide, carbon monoxide, and photochemical oxidants. It also
               establishes maximum permissible limits on exhaust gases from motor vehicles.
               The Automobile Nitrogen Oxides Law sets the fundamental policies and plans for reducing the total volume of
               nitrogen oxides for specific automobiles.
China          Although the government does not require the reporting of data on ozone concentrations, the city of Beijing
               does so when ozone levels become particularly high.
               Euro I and II standards for the control of motor vehicle emissions, including carbon monoxide, hydrocarbons,
               and nitrogen oxides.
Mexico         Mexico’s Tag Zero Program offers a 2-year exemption from Mexico City’s “car-free” policy for drivers of clean
               cars. Under the program, drivers of new cars or cars that have been upgraded with catalytic converters may
               drive in the city any day of the week, while owners of cars without such certification may drive on only a certain
               number of days per week. (An exempted, or clean, car is denoted by a zero on a sticker placed on the back
               window of the car. The car’s license plate indicates the days a car may not be driven if it does not have a
               sticker.) The Tag Zero program thus rewards the purchase of clean vehicles.

India          Euro I and II standards for the control of motor vehicle emissions, including carbon monoxide, hydrocarbons,
               and nitrogen oxides.
Source: GAO.
                                    a
                                     The Nitrogen Oxides SIP Call is authorized under section 110 of the Clean Air Act. A SIP is a State
                                    Implementation Plan, which is a proposal submitted by each state to EPA containing emission
                                    limitations and other control measures to attain, maintain, and enforce the NAAQS. EPA may issue a
                                    SIP Call under the act when it finds that the applicable SIP fails to comply with a requirement of the
                                    act. The SIP Call requires the state to revise its SIP.




                                    Page 60                                             GAO-03-25 Air Pollutants and Climate Change
Appendix V

Summary of Results of Selected Studies
on Economic Growth and Environmental
Pollution                                                                                                                                        Append
                                                                                                                                                      x
                                                                                                                                                      i
                                                                                                                                                      V




                                             The following table presents information on the studies of economic
                                             growth and environmental quality that we reviewed.



Table 2: Results of Selected Studies of Economic Growth and Environmental Quality

                                                                                    Estimated per capita income for turning points,
                                                                                                by type of emissiona
Study’s author(s) and year                                                     Particulate matter          Sulfur dioxide    Carbon dioxide
Based on exchange rates
Grossman and Krueger, “Economic Growth and Environment,”                               None foundb                $4,100           Not studied
Quarterly Journal of Economics (1995)
Holtz-Eakin and Selden, “Stoking the Fires? CO2 Emissions and                           Not studied           Not studied             $35,400c
Economic Growth,” Journal of Public Economics (1995)
Panayotou, “Demystifying the Environmental Kuznets Curve: Turning a                     Not studied                5,000           Not studied
Black Box into a Policy Tool,” Environment and Development Economics
(1997)
Roberts and Grimes, “Carbon Intensity and Economic Development                          Not studied           Not studied          None found
1962-91: A Brief Exploration of the Environmental Kuznets Curve,”
World Development (1997)
Based on purchasing power parity
Shafik, “Economic Development and Environmental Quality:                                     $3,300                3,700           Not studied
An Econometric Analysis,” Oxford Economic Papers (1994)
Selden and Song, “Environmental Quality and Development: Is There a                           9,600               10,700           Not studied
Kuznets Curve for Air Pollution Emissions?,” Journal of Environmental                         9,800                8,900
Economics and Management (1994)—two models estimated
Cole, Rayner, and Bates, “The Environmental Kuznets Curve: An                                 7,300                5,700                25,100
Empirical Analysis,” Environment and Development Economics                                    8,100                6,900                62,700
(1997)—two models estimated
Schmalensee, Stoker, and Judson, “World Carbon Dioxide Emissions:                       Not studied           Not studied               10,000
1950-2050,” Review of Economics & Statistics (1998)
Unruh and Moomaw, “An Alternative Analysis of Apparent EKC-type                         Not studied           Not studied          None found
Transitions,” Ecological Economics (1998)
Panayotou, Sachs, and Peterson, “Developing Countries and the                           Not studied           Not studied               12,000
Control of Climate Change: Empirical Evidence,” Discussion Papers
#45, Harvard Institute for International Development (1999)
Stern and Common, “Is There an Environmental Kuznets Curve for                          Not studied             101,200d           Not studied
Sulfur?” Journal of Environmental Economics and Management (2001)
Source: GAO.
                                             a
                                                 All numbers are in 1985 dollars unless otherwise noted.
                                             b
                                              Grossman and Krueger estimated a turning point separately for heavy particulate and smoke. While
                                             no turning point for heavy particulate was found, the turning point for smoke was $6,200.
                                             c
                                              In 1986 dollars.
                                             d
                                                 In 1990 dollars.




                                             Page 61                                              GAO-03-25 Air Pollutants and Climate Change
Appendix VI

GAO Contact and Staff Acknowledgments                                                           Appendx
                                                                                                      iVI




GAO Contact       David Marwick, (202) 512-6775



Acknowledgments   In addition to the individual named above, Bernice H. Dawson, Richard A.
                  Frankel, Anne K. Johnson, Mehrzad Nadji, and Carol Herrnstadt Shulman
                  made key contributions to the report. Important contributions were also
                  made by Laura Yannayon and Katherine M. Raheb.




(360150)          Page 62                             GAO-03-25 Air Pollutants and Climate Change
GAO’s Mission            The General Accounting Office, the audit, evaluation and investigative arm of
                         Congress, exists to support Congress in meeting its constitutional responsibilities
                         and to help improve the performance and accountability of the federal government
                         for the American people. GAO examines the use of public funds; evaluates federal
                         programs and policies; and provides analyses, recommendations, and other
                         assistance to help Congress make informed oversight, policy, and funding
                         decisions. GAO’s commitment to good government is reflected in its core values of
                         accountability, integrity, and reliability.


Obtaining Copies of      The fastest and easiest way to obtain copies of GAO documents at no cost is
                         through the Internet. GAO’s Web site (www.gao.gov) contains abstracts and full-
GAO Reports and          text files of current reports and testimony and an expanding archive of older
                         products. The Web site features a search engine to help you locate documents
Testimony                using key words and phrases. You can print these documents in their entirety,
                         including charts and other graphics.
                         Each day, GAO issues a list of newly released reports, testimony, and
                         correspondence. GAO posts this list, known as “Today’s Reports,” on its Web site
                         daily. The list contains links to the full-text document files. To have GAO e-mail this
                         list to you every afternoon, go to www.gao.gov and select “Subscribe to GAO
                         Mailing Lists” under “Order GAO Products” heading.


Order by Mail or Phone   The first copy of each printed report is free. Additional copies are $2 each. A check
                         or money order should be made out to the Superintendent of Documents. GAO
                         also accepts VISA and Mastercard. Orders for 100 or more copies mailed to a single
                         address are discounted 25 percent. Orders should be sent to:
                         U.S. General Accounting Office
                         441 G Street NW, Room LM
                         Washington, D.C. 20548
                         To order by Phone:     Voice: (202) 512-6000
                                                TDD: (202) 512-2537
                                                Fax: (202) 512-6061


To Report Fraud,         Contact:
                         Web site: www.gao.gov/fraudnet/fraudnet.htm
Waste, and Abuse in      E-mail: fraudnet@gao.gov
Federal Programs         Automated answering system: (800) 424-5454 or (202) 512-7470



Public Affairs           Jeff Nelligan, Managing Director, NelliganJ@gao.gov (202) 512-4800
                         U.S. General Accounting Office, 441 G Street NW, Room 7149
                         Washington, D.C. 20548
United States                  Presorted Standard
General Accounting Office      Postage & Fees Paid
Washington, D.C. 20548-0001           GAO
                                 Permit No. GI00
Official Business
Penalty for Private Use $300
Address Service Requested