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U.S. DEPARTMENT OF STATE
CLIMATE ACTION REPORT
SEPTEMBER 1994
Climate Action Report
Submission of the United States of America Under the
United Nations Framework Convention on Climate Change
Table of Contents
1. Introduction and Overview
The Science.........................5
National Circumstances:
A Context for U.S. Action.........7
Inventory of Greenhouse Gases.......8
U.S. Mitigation Actions............10
Progress Toward Implementation.....14
Impacts and Adaptation.............14
Research and Public Education......15
International Activities...........16
The Future.........................16
2. National Circumstances
The U.S. Climate...................20
U.S. Population Trends.............22
U.S. Natural Resources.............24
Land Resources...................24
Biological Resources.............27
Water Resources..................28
Energy Resources.................28
The U.S. Economy...................30
Government and the Market Economy.30
Composition and Growth...........31
The U.S. Federal Budget..........32
National Revenue Structure.......33
U.S. Energy Production and
Consumption......................36
Energy Production................36
Energy Consumption...............39
U.S. Governing Institutions........43
Federal Departments and Agencies.43
The U.S. Congress................43
State and Local Governments......44
The U.S. Court System............44
Scientific Institutions..........45
U.S. Policies Related to Climate
Change...........................46
Agriculture and Land-Use Policies.46
Environmental Policies...........46
Energy Policies..................47
Transportation Policies..........48
3. Greenhouse Gas Inventory
Recent Trends in
U.S. Greenhouse Gas Emissions....53
Carbon Dioxide Emissions...........57
The Energy Sector................58
Industrial Processes.............60
Changes in Forest Management
and Land Use.....................61
Methane Emissions..................63
Landfills........................64
Agriculture......................64
Coal Mining......................65
Oil and Natural Gas Production
and Processing.................66
Other Sources of Methane.........66
Nitrous Oxide Emissions............67
Agricultural Soil Management
and Fertilizer Use.............67
Fossil Fuel Combustion...........68
Adipic Acid Production...........68
Nitric Acid Production...........68
Other Sources of N2O.............68
HFC and PFC Emissions..............70
Emissions of Criteria Pollutants...72
4. Mitigation: The Action Plan
The Plan and Its Development.......77
The Effects of the Plan..........77
Applying a Portfolio Approach....78
Developing the Plan: A Public
Process........................79
Assessing the Effects of the Plan.80
Carbon Dioxide.....................83
Energy-Demand Strategies.........83
Energy-Supply Strategies.........91
Forestry Strategies..............94
Methane and Other Gases............97
Methane Recovery and Reduction
Strategies.....................97
HFC and PFC Control Strategies...98
Nitrous Oxide Strategy...........99
State and Local Outreach..........100
Industrial and Commercial
Efficiency Programs.............100
EPA's State and Local Outreach
Program.......................100
Agricultural Outreach Programs..101
Joint Implementation..............102
5. Impacts and Adaptation
The Adaptability of Natural
Systems.........................109
U.S. Ecosystem Management
Initiative....................111
Contingency Planning............112
Federal Interagency Coordination:
CENR..........................114
Resource Adaptation Strategies....117
Water Supplies..................117
Coastal Zones...................120
Agricultural Land...............122
Forests.........................124
"Lightly Managed" Ecosystems....126
6. Research and Public Education
The U.S. Global Change
Research Program................133
Atmospheric Constituents Important
to Climate Change.............134
Understanding the Carbon Cycle..138
Terrestrial and Marine Ecosystems.138
Socioeconomic and Policy
Implications of Climate Change.140
Research on Mitigating Climate
Change........................141
Coordination With International
Research Efforts..............142
Public Education and
Communications..................148
Educational Outreach............148
The GLOBE Program...............149
Project Earthlink...............149
Individual Agency Efforts.......151
7. International Activities
Bilateral Technical
and Financial Cooperation.......155
Country Studies.................155
Bilateral Mitigation Projects...157
Information Sharing and Trade
Facilitation..................172
Bilateral Assistance for Adaptation.174
Multilateral Technical
and Financial Cooperation.......178
Framework Convention on Climate
Change........................178
Other Relevant Conventions
and Agreements................178
Global Environment Facility.....179
Multilateral Development Banks..180
Organization for Economic
Cooperation and Development...181
International Energy Agency.....181
Asia-Pacific Economic Cooperation.182
Other Fora......................182
Nongovernmental Efforts.........182
8. The Future
Meeting Year 2000 Commitments.....186
Changes in Modeling Assumptions.187
Responses to Changing
Circumstances.................188
Post-2000 Actions.................190
Technology Research and
Development Strategy..........191
The Transportation Sector.......191
A Long-Run Strategy.............192
International Regime..............193
Strengthening Links
Between Science and Policy....194
Establishing a New "Aim"........194
Developing Common Actions
and Technology Initiatives....192
Endorsing Joint Implementation..195
Enlisting Public- and
Private-Sector Expertise......195
Strengthening the Convention
Process.......................196
References.............................198
Chapter 1. Introduction
In June 1992 in Rio de Janeiro, world leaders and citizens of 176
countries gathered to agree on ways of working together to preserve
and enhance the global environment. The Earth Summit aroused the
hopes and dreams of people around the world and set in motion
ambitious plans to address the planet's greatest environmental
threats. We shared a common vision: to provide a higher quality of
life for ourselves and our children.
At the Earth Summit, the United States joined other countries in
signing the Framework Convention on Climate Change, an international
agreement whose ultimate objective is to:
achieve -- stabilization of greenhouse gas concentrations in the
atmosphere at a level that would prevent dangerous anthropogenic
interference with the climate system. Such a level should be achieved
within a time frame sufficient to allow ecosystems to adapt naturally
to climate change, to ensure that food production is not threatened,
and to enable economic development to proceed in a sustainable
manner.
The United States--and the international community-- has confronted
the threat of global climate change because most scientists agree
that the threat is real. There is no doubt that human activities are
increasing atmospheric concentrations of greenhouse gases, especially
carbon dioxide, methane, and nitrous oxide. Models predict that these
increases in greenhouse gases will cause changes in climate locally,
regionally, and globally, with potential adverse consequences to
ecological and socioeconomic systems. The best current predictions
suggest that the rate of climate change could far exceed any natural
changes that have occurred in the past 10,000 years. Of course, there
are uncertainties regarding the magnitude, timing, and regional
patterns of climate change. But any human-induced change that does
occur is not likely to be reversed for many decades--or even
centuries--because of the long atmospheric lifetimes of the
greenhouse gases and the inertia of the system.
With this global threat in mind, President Clinton stated on Earth
Day 1993:
We must take the lead in addressing the challenge of global warming
that could make our planet and its climate less hospitable and more
hostile to human life. Today, I reaffirm my personal and announce our
nation's commitment to reducing our emissions of greenhouse gases to
their 1990 levels by the year 2000. I am instructing my
Administration to produce a cost-effective plan -- that can continue
the trend of reduced emissions. This must be a clarion call, not for
more bureaucracy or regulation or unnecessary costs, but instead for
American ingenuity and creativity to produce the best and most
cost-efficient technology.
In October 1993, the United States released The Climate Change Action
Plan, detailing the initial U.S. response to climate change. The Plan
outlined a comprehensive set of measures to reduce net emissions,
covering greenhouse gases in all sectors of the economy. It focused
on partnerships between the government and the private sector to help
solve this pressing problem, and is now undergoing rapid
implementation. The Plan laid a foundation for U.S. participation in
the international response to the climate challenge. And finally, the
Plan included a process for monitoring its effectiveness and for
adapting to changing circumstances.
This document, the Climate Action Report, represents the first formal
U.S. communication under the Framework Convention on Climate Change,
as required under Articles 4.2 and 12. It is a snapshot--a
description of the current U.S. program. It does not seek to identify
additional policies or measures that might ultimately be taken as the
United States continues to move forward in addressing climate change,
nor is it intended to be a revision of the U.S. Climate Change Action
Plan. It is not a substitute for existing or future decision-making
processes--whether administrative or legislative--or for additional
measures developed by or with the private sector. Meeting the formal
reporting requirements in the Climate Convention, this document is
also intended to identify existing policies and measures, and thus to
assist in establishing a basis for considering future actions.
This document has been developed using the methodologies and format
agreed to at the Ninth Session of the Intergovernmental Negotiating
Committee for a Framework Convention on Climate Change. We assume
that this communication, like those of other countries, will be
reviewed and discussed in the evaluation process for the Parties of
the Convention. We hope that the measures detailed here provide
useful examples of possible directions for the future.
This chapter briefly describes the climate-system science that sets
the context for U.S. action, and then provides an overview of the
U.S. program, which is the focus of the remainder of this report. In
particular, the United States includes information in this report on:
national circumstances, providing a context for action; an inventory
of U.S. greenhouse gas emissions; mitigation programs; adaptation
programs; research and education programs; international activities,
including contributions to international financial mechanisms that
address climate change; and a brief discussion of the future
direction of the U.S. effort.
The Science
The scientific community has long noted the potential for human
activities to contribute to global climate change. A broad
international consensus regarding this issue has been developed over
the past several years (and has been reported in the
Intergovernmental Panel on Climate Change assessment reports); this
summary is drawn from that consensus view. As the actions being taken
by the United States ultimately depend on our understanding of the
science, it is appropriate to review this information here.
The driving energy for weather and climate comes from the sun (Figure
1-1). The Earth intercepts solar radiation (short-wave and visible
parts of the spectrum). About one-third of that radiation is
reflected, and the rest is absorbed by different components of the
climate system, including the atmosphere, the oceans, the land
surface, and biota. The energy absorbed from solar radiation is
balanced, in the long term, by outgoing radiation from the
Earth-atmosphere system. This terrestrial radiation takes the form of
long-wave, invisible infrared energy. The magnitude of this outgoing
radiation is determined by the temperature of the Earth--atmosphere
system.
Several natural and human activities can change the balance between
the energy absorbed by the Earth and that emitted in the form of
long-wave, infrared radiation. These activities are both natural
(including changes in solar radiation and volcanic eruptions) and
human-induced, arising from industrial and land-use practices that
release or remove heat-trapping "greenhouse" gases, thus changing the
atmospheric composition.
Greenhouse gases include water vapor, carbon dioxide (CO2), methane
(CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs),
hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs),
perfluorocarbons (PFCs), and ozone (O3). While water vapor has the
largest effect, its concentrations are not directly affected, on a
global scale, by human activities. Although most of these gases
occur naturally (the exceptions are CFCs, HCFCs, HFCs, and PFCs),
human activities have contributed significantly to increases in their
atmospheric concentrations. Many greenhouse gases have long
atmospheric residence times (several decades to centuries), which
implies that the atmosphere will recover very slowly from such
emissions, if at all.
Internationally accepted science indicates that increasing
concentrations of greenhouse gases will ultimately raise atmospheric
and oceanic temperatures and could alter associated circulation and
weather patterns. Large computer-driven climate models predict that
the equilibrium change in the average temperature of the globe's
atmosphere as a consequence of doubling of CO2 or its equivalent is
unlikely to lie outside the range of 1.5--4.5-C (2.5--8-F), with a
best estimate of 2.5-C (4.5-F). The sea level rise associated with
such doubling has been estimated to range between a few centimeters
and one meter (about 2 inches to 3 feet), with a best estimate of
approximately 20 centimeters (8 inches). Because of the large thermal
inertia of the Earth system, the equilibrium warming from added
greenhouse gases is not reached until many decades after these
emissions are released into the atmosphere.
While current analyses are unable to predict with confidence the
timing, magnitude or regional distribution of climate change, the
best scientific information indicates that such changes are very
likely to occur if greenhouse gas concentrations continue to
increase.
National Circumstances: A Context for U.S. Action
A nation's vulnerability and response to climate change are greatly
affected by its institutions, governing structures, economic
arrangements, energy use patterns, land uses, population growth and
distribution, and many other factors. U.S. policymakers must take
into account the complexities and special characteristics of the
political, social, and economic orders in the United States. A
description of land-use patterns sets the context for the discussion,
in a subsequent chapter, of climate change impacts and adaptation
measures, while energy, economic, and political factors shape the
U.S. approach to mitigating climate change.
The United States is by far the world's largest economy, although
per-capita GDP growth has slowed in recent years. The United States
is also the world's largest producer and consumer of energy, and the
largest producer of greenhouse gases. U.S. energy intensity (the
amount of energy required to produce a unit of GDP) has improved by
27 percent from its 1970 peak, remaining stable since 1986. Like
other industrialized countries, the United States relies heavily on
fossil fuels to power its industrial, residential, and transportation
sectors, although, as in other countries, renewable-energy sources,
such as solar and biomass fuels, are anticipated to supply greater
amounts of power in the coming decades.
Despite dramatic increases in the number of residences, number of
electrical appliances, and the amount of heated space per person,
residential energy use has remained roughly constant, due to
efficiency improvements. Energy use in the commercial sector has
increased substantially, however, due to that sector's extremely
rapid growth. Industrial energy intensity has improved by over 35
percent since 1972, resulting in energy savings of more than 12
quadrillion BTUs annually. A 34 percent decrease in average
per-kilometer fuel consumption has partly offset a 50 percent
increase in vehicle kilometers traveled since 1969, resulting in
continuing growth of energy consumption and associated greenhouse gas
emissions in the transportation sector.
The United States has a large and diverse land area of approximately
931 million hectares (2.3 billion acres) including cropland,
grassland, pastures, ranges, wetlands, urban/suburban areas,
protected areas, and other special uses. Forested areas have expanded
in the past twenty years, though the amount of old-growth forests
continues to decline. While total wetland areas have declined over
the past several decades, the rate of decline has slowed; wetlands
are anticipated to be among the land areas most severely affected by
climate change. The amount of land devoted to urban use continues to
increase, although only approximately 4.5 percent of total land area
is classified as urban. U.S. population growth is slow overall,
though immigration and internal migration contribute to faster growth
in the South and in coastal regions, resulting in increased stress to
coastal zones and heightened vulnerability to climate change. Low
population densities in the United States result in relatively high
energy use per capita, despite significant improvements in energy
efficiency.
The United States has a market economy; the government has long
played an important role in intervening to correct market failures
and achieve various social ends. All levels of government have been
involved in the protection of the environment. The federal
government has actively sought to improve the quality of the natural
environment and promote public health for the past twenty-five years.
Most recently, government policies in a wide range of sectors are
increasingly showing an awareness of the challenge of climate change.
The Clinton Administration has made the formulation and
implementation of its comprehensive Climate Change Action Plan a
national priority.
Inventory of Greenhouse Gases
The Framework Convention on Climate Change calls upon Parties to:
"periodically update, publish, and make available to the Conference
of Parties -- national inventories of anthropogenic emissions by
sources and removals by sinks of all greenhouse gases not controlled
by the Montreal Protocol, using comparable methodologies to be agreed
upon by the Conference of the Parties." This commitment was included
in the Convention because it was clear to all countries that any
effective climate policy must begin with an accurate inventory of
gases that may influence global warming. A useful inventory must take
into account the global warming potential of the various gases and
analyze their production by different sectors of the economy, as well
as account for their sequestration by carbon sinks, such as forests.
At the Ninth Session of the Intergovernmental Negotiating Committee
(INC), guidelines for preparing greenhouse gas inventories were
adopted; the discussion in this report follows the agreed format.
The most important anthropogenic greenhouse gases are carbon dioxide,
methane, and nitrous oxide. Atmospheric concentrations of all three
have increased significantly since the Industrial Revolution, almost
certainly because of human activities. Based on a recent
recomputation of 1990 U.S. greenhouse gas emissions following the INC
guidelines, the United States estimates that net emissions totaled
1,348 million metric tons of carbon equivalent (MMTCE) (Table 1-1).
This represents a decrease in the previous estimate of 1,462 MMTCE,
which was used in the development of The Climate Change Action Plan.
The relative effects of greenhouse gases can be compared using
"global warming potentials." According to the 1990 inventory carried
out by the United States, carbon dioxide accounted for 85 percent of
the total global warming potential of all U.S. anthropogenic
emissions not controlled by the Montreal Protocol, followed by
methane with 11 percent, nitrous oxide with 3 percent, and
hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) with 1 percent.
These percentages have not changed significantly since 1990, although
the use of HFCs and PFCs is expected to increase in future years.
Total emissions have increased slightly since 1990 (Figure 1-2).
U.S. emissions of carbon dioxide, the principal anthropogenic
greenhouse gas, are divided fairly evenly among industry (34
percent), transportation (31 percent), and utilities (35 percent, of
which residences account for 19 percent and commercial buildings for
16 percent). Absorption of carbon dioxide in U.S. forests (carbon
"sinks") has increased in recent years. The principal sources of
anthropogenic methane emissions are landfills (37 percent) and
agriculture (32 percent), with coal, oil, and natural gas production
accounting for most of the remainder. Nitrous oxide, an extremely
potent greenhouse gas, is released principally through nitrogen-based
fertilizers and industrial production of synthetic fiber. Also
included in the U.S. inventory are carbon monoxide (CO), nitrogen
oxides (NOX), and nonmethane volatile organic compounds (NMVOCs).
These compounds have an indirect effect on climate change--for
example, by increasing the atmospheric life of methane. Their
relative and absolute contributions to climate change are uncertain.
U.S. Mitigation Actions The Climate Convention calls for Annex I
Parties (developed countries and countries with economies in
transition to market economies) to aim to return their emissions of
greenhouse gases to their 1990 levels by the year 2000. As with the
reporting of inventories, the Intergovernmental Negotiating
Committee, at its Ninth Session, agreed on a format for reporting
measures to address emissions and sinks of greenhouse gases. This
report follows that recommended format.
The basis for the U.S. response to the challenge set forth in the
Convention is The Climate Change Action Plan, announced by President
Clinton and Vice President Gore in October 1993. The Plan blends
market incentives, voluntary initiatives, research and development,
improved regulatory frameworks, and intensified existing programs to
achieve the reductions in emissions necessary to meet the U.S.
commitment. As noted above, in 1990, U.S. emissions totaled 1,462
million metric tons of carbon equivalent (MMTCE). The Action Plan
projects an emission level of 1,459 MMTCE by the year 2000, based on
factors as anticipated in the fall of 1993.
The emission estimates reported in this section are slightly
different from those used in the inventory described above. The data
in the inventory chapter reflect recent guidance from the INC, which
was only received after the actions in this section were proposed,
analyzed, and adopted. A complete description of the inventory values
used in Chapter 3 are reported in Inventory of U.S. Greenhouse Gas
Emissions and Sinks for 1990--1993 (U.S. EPA 1994); and a description
of the inventory estimates used in developing the emission reductions
projected in this section are provided in The Climate Change Action
Plan: Technical Supplement (U.S. DOE 1994). Along with this report,
both documents are provided to the Parties of the Climate Convention
as part of the formal U.S. submission.
The Plan's comprehensive, portfolio approach addresses energy demand
in all sectors, as well as energy supply and forestry (Table 1-2).
This broad approach lessens the risk that poor performance in one
sector will jeopardize the Plan as a whole. It is also
cost-effective. In undiscounted dollars, the approximately $60
billion in costs for the Plan from 1994 to 2000 are anticipated to be
offset by approximately $60 billion in energy savings for businesses
and consumers by 2000. An additional $200 billion in savings is
anticipated for 2001--2010. Voluntary programs and market-based
incentives are at the heart of the U.S. approach. Two of the most
prominent programs in this effort are Green Lights and Climate
Challenge. In the Green Lights program, over 1,500 organizations have
committed to a national effort to improve the efficiency of their
lighting systems. And more than 750 utilities, representing over 80
percent of U.S. electric utility generation capacity, have already
signed up for the Climate Challenge, under which they will inventory
current emissions and commit to undertake and to report on actions to
reduce greenhouse gases. Other aspects of the Plan improve
information flows to private companies and encourage the accurate
valuation of energy costs throughout corporate structures.
The Plan also concentrates on the reduction of methane and nitrous
oxide, both of which have a greater global warming potential than
carbon dioxide, ton for ton, and includes strategies to limit the
growth of HFC and PFC emissions.
Although the United States provides a blueprint for reaching the
near-term aim of the Climate Convention through domestic measures
alone, it also recognizes the contribution that "joint
implementation" could make toward achieving the Convention's goals.
Thus, the United States is promoting cooperative efforts with other
countries to take measures to reduce or sequester carbon. Toward this
end, the United States has announced the U.S. Initiative on Joint
Implementation, which sets ground rules for the qualification and
evaluation of joint implementation projects.
Progress Toward Implementation
On the basis of assumptions regarding the costs of energy, the rate
of growth of the U.S. economy, and the availability of funding for
the programs outlined in the Plan, the United States projected a
return of its greenhouse gas emissions to their 1990 levels by the
year 2000. However, since the time these projections were prepared
and the U.S. Action Plan was published, the economy has grown at a
more robust rate than anticipated, the price of oil fell sharply
before recently rising toward projected levels, and the U.S.
Congress, which must appropriate funding for federal agency programs,
does not, for now, appear likely to provide full funding for the
actions contained in the Plan.
However, differences between earlier assumptions and current
circumstances are only now being evaluated. Furthermore, the coming
months will cause changes, either increasing or decreasing the gap.
For example, the outstanding industry response seen in voluntary
programs that are "unscored" in the current Plan could deliver
benefits sufficient to make up any shortfall in "scored" programs. As
a consequence, it is not yet possible to present a modified
projection of the effects of measures outlined in Chapter 4 on
mitigation as a function of this difference, or to detail the
additional measures that may be taken to close the gap. The United
States is committed to a full review of the U.S. Action Plan in late
1995. In this review, a comprehensive analysis of the overlapping
effects of the changes in economic assumptions and funding levels--as
well as changes in the anticipated effects of individual
measures--will be made. It is anticipated that, as a result of this
review process, additional measures will be taken to ensure that the
U.S. commitment is met.
Impacts and Adaptation
The impact of global change on natural ecosystems cannot be predicted
with accuracy, in part because these complex systems are not yet well
understood. The government is working to increase our knowledge base
through the federal interagency Committee on Environment and Natural
Resources and through the U.S. Ecosystem Management Initiative. Both
of these efforts bring together experts from many federal agencies to
examine how systems can be understood and kept healthy in their
totality. However, despite the best efforts of governments to deal
with the climate threat, it is unlikely that climate alteration can
be avoided entirely. Further study is needed to see how natural
systems can best adapt to climate change.
The National Academy of Sciences, the National Academy of
Engineering, and the Institute of Medicine recently looked into the
effects of climate change on the various principal ecosystems found
in the United States (NAS/NAE/IM 1992). They found that U.S. water
supplies, particularly some of the more vulnerable river systems,
would be greatly influenced by possible increases in evaporation and
changes in rain patterns. The extremely delicate wetlands and
estuarine waterways found in U.S. coastal zones could be affected by
sea level rise, alterations in upland water flow, human settlement
patterns, and other consequences of a changed climate. U.S.
agriculture and industry appeared relatively less vulnerable to
climate change. Lightly managed ecosystems of whatever type, by
contrast, appeared extremely vulnerable. Forest systems might find
that their most favorable climates shift hundreds of miles to the
north, perhaps too rapidly for the trees to adapt. Work on
understanding the impacts from and adaptation to the effects of
climate change will remain a priority of federal agencies for many
years to come.
Among the key areas on which U.S. adaptation efforts focus are
contingency planning and consideration of uncertainty in ranges of
potential outcome. The increased unpredictability of future events
due to climate change and the increased risks of surprises or
large-scale losses render this effort all the more important. Some of
the efforts to manage for increased vulnerability include the
establishment of the Floodplain Management Task Force, the efforts to
better predict "El Ni$o" events (which lead to global changes in
atmospheric behavior over relatively short periods), and water-use
and coastal zone management programs, which focus on some of the most
vulnerable systems.
Research and Public Education
Paramount to successfully mitigating and adapting to climate change
is an ability to understand, monitor, and predict future changes.
This, in turn, requires substantial research on the global climate
system and the dissemination of such information to better enable
society to respond appropriately. To address these needs, the United
States has developed the U.S. Global Change Research Program, which,
with a proposed budget in fiscal year 1995 of $1.8 billion, is the
largest climate change research program in the world.
The U.S. Research Program, which is part of the Committee on
Environment and Natural Resources, supports a wide range of
policy-relevant research programs. These include trace atmospheric
species and their effects on climate, the role of terrestrial and
marine ecosystems in climate change and the impacts of climate change
on these ecosystems, the socioeconomic and policy implications of
climate change, and potential measures to mitigate and adapt to
climate change. To facilitate the full and open exchange of climate
change data, the U.S. Research Program is developing the Global
Change Data and Information System, which will provide the
infrastructure for linking global change data bases and information
available within the various agencies of the federal government and
will make them available to the public.
Recognizing the importance of international cooperation in global
change research, the United States plays a major role in a variety of
international efforts to understand and assess the state of knowledge
about global change. The U.S. Research Program, in addition to its
key role in support of domestic efforts, is a major contributor to
international global change research programs, primarily through the
Intergovernmental Panel on Climate Change, the World Climate Research
Program, the International Geosphere-Biosphere Program, and the Human
Dimensions of Global Environmental Change Program. In addition the
United States is engaged in bilateral research projects and
internationally coordinated research programs involved with climate
change, placing special emphasis on the development of networks and
institutes to promote the development of regional capabilities to
conduct global change research. Similarly, U.S. scientists are
contributing research information and are playing leadership roles in
the assessments of the Inter-governmental Panel on Climate Change,
which is supplying much of the scientific input to the international
policy decisions on climate change.
Since decision making on national response strategies to climate
change ultimately resides with the public, the U.S. is beginning to
develop programs for general education, communication, and
dissemination of climate change information. While many of these
activities are organized under the U.S. Research Program, its member
agencies have longstanding programs for educational outreach, many of
which now are being extended to include climate change information
and are turning from a purely domestic focus to include international
activities.
International Activities
The success of the Framework Convention on Climate Change relies
preeminently on cooperation among nations. To foster closer
international cooperation on climate change, the United States is
engaged in a wide range of bilateral and multilateral activities.
The United States provides technical assistance and facilitates the
transfer of energy-efficient technologies through its Country Studies
program, bilateral mitigation and adaptation projects, and
information sharing and trade facilitation. The Country Studies
program, funded at $25 million over two years, helps developing
countries and countries with economies in transition generate
inventories of greenhouse gases, assess their vulnerability to
climate change, and evaluate strategies for reducing net emissions of
greenhouse gases and adapting to the potential impacts of climate
change.
Over thirty-five bilateral projects aimed at mitigating climate
change are supported by the U.S. government, through the U.S. Agency
for International Development and other key agencies involved in the
climate change issue. U.S. bilateral mitigation projects totaling
about $1.5 billion include efforts on energy demand, power generation
and distribution, renewables, clean coal, privatization, clean air,
methane, and forestry. As part of its bilateral assistance programs,
the United States also helps build capacity in countries to assess
and/or minimize vulnerability to climate change.
A critical element of technology transfer is making information about
available technologies easily accessible to foreign government
agencies and private-sector firms, and helping them secure financing
for beneficial technologies. To meet this need, the United States has
established a number of information-sharing and trade-facilitation
programs, with 1994 funding for such projects totaling more than $10
million.
In multilateral fora related to global climate change policy matters,
the United States plays a leadership role, which carries with it
considerable financial responsibilities. In addition to participating
actively in the Intergovernmental Negotiating Committee (INC) for a
Framework Convention on Climate Change, the United States has
provided substantial financial resources to both the trust fund
enabling developing countries to participate in the negotiations, and
a separate trust fund to support the basic costs of the negotiations
and the INC Secretariat.
In support of the Global Environment Facility (GEF), the United
States has pledged $430 million (out of a $2 billion total) to the
GEF's replenishment. U.S. bilateral programs will continue to
strengthen collaboration with the restructured GEF as a complement to
U.S. contributions to the core fund.
The Future
The United States is making significant strides toward reducing
greenhouse gas emissions to their 1990 levels by the year 2000. To
track the effectiveness of the programs and measures being
implemented under The Climate Change Action Plan, U.S. agencies have
established individual and joint tracking systems to develop
performance indicators and progress milestones. Interim assessments
to date show that significant progress has been made in meeting--and
in some cases exceeding--these milestones, while in other cases
specific measures are not performing as well as expected. However,
the overall combination of changes in economic growth, in oil prices,
and in energy demand currently suggests that the United States may
need to implement additional measures to meet its commitment to
return emissions to their 1990 level by the year 2000. It is
important to recognize that the future effectiveness of current
actions may be enhanced or diminished by changing circumstances in
the domestic and international arenas.
As recommended by the guidelines adopted at the INC's Ninth Session
(UN/INC 1994), the United States has also provided a preliminary
estimate of its emissions of greenhouse gases through the year 2010.
Although the United States will continue to revise this estimate, the
preliminary results indicate that to meet the ultimate objective of
the Convention, the United States, and all nations, will need to
develop additional measures to combat the longer- term trend of
rising emissions. Toward this end, the United States has established
a working group to devise a long-run strategy for examining all
policies that could affect U.S. greenhouse gas emission levels beyond
the year 2000, with particular attention being given to accelerating
technology research, development, and deployment.
Finally, in addition to continued activity in the domestic arena, the
United States has been, and will continue to be, an active
participant in international negotiations under the United Nations
Framework Convention on Climate Change.
Chapter 2. National Circumstances
A country's climate, economic health and composition, demographic
trends, political and institutional systems, energy production and
consumption, and natural resources determine its vulnerability and
adaptability to the effects of climate change. Identifying the
opportunities for and costs of reducing the likelihood of climate
change by adopting policies to limit greenhouse gas emissions and
augment sinks also requires a thorough examination of all of these
factors.
Perhaps the key element of a country's national
circumstances is its political will. The Clinton Administration has
made the formulation and implementation of its Climate Change Action
Plan a priority, demonstrated by Chapter 4 of this document, which
presents a detailed plan for mitigating greenhouse gas emissions to
1990 levels by the year 2000. Furthermore, many of the elements of
the Plan have already been implemented, while an effort is under way
to obtain legislative approval for others.
This chapter presents a snapshot of the national characteristics of
the United States, current conditions and trends in those conditions,
and their link to climate change issues and policymaking.
The U.S. Climate
The climate zones of the United States are representative of all the
major regions of the world, except the ice cap (Figure 2-1). Some
states encompass as many as five distinct climate types. Because of
this broad diversity, describing the effects of climate change on the
United States as either positive or negative overall would be an
oversimplification. For example, states with cooler climates may have
extended growing seasons and lower heating bills. In the Sunbelt, on
the other hand, energy consumption for cooling may rise, along with
the emissions it generates (Figure 2-2). The net effect on energy
consumption would depend on the net change in heating- and
cooling-degree days.
Baseline rainfall levels are also central to determining the
vulnerability of the United States to global warming. Most of the
western states are currently arid. The reduced rainfall and increased
evaporation from global warming projected for midcontinental areas of
the United States by general circulation models may exacerbate the
scarcity of freshwater resources in those states. And although the
eastern states have only rarely experienced severe drought, they are
increasingly vulnerable to flooding and storm surges--particularly in
densely populated coastal area--as sea level rises. If extreme
weather events--such as tornadoes, hurricanes, and floods--occur with
greater frequency and/or intensity, damages could be very extensive.
However, there is great uncertainty about whether extreme events will
become more common as a result of climate change.
Climate change may also benefit some plants and animals. Warmer
temperatures may allow them to expand their range northward. Higher
levels of CO2 may boost the growth and productivity of some
plants--particularly agricultural crops, where nutrients can be
closely monitored.
U.S. Population Trends
Demographic factors are critical determinants of a nation's economic
and environmental health, its vulnerability to climate change, and
its ability to mitigate and adapt to the effects of climate change.
In particular, population levels and growth drive a nation's
consumption of energy and other resources, while settlement patterns
and population density affect dependence on transportation, the
availability of land for various uses, and the vulnerability of
coastal areas to flooding in the event of sea level rise.
With a population of over 250 million in 1993, the United States is
the third most populous country in the world, after China and India.
Its population density, however, is far lower: 27 people per square
kilometer, versus 126 and 304 people per square kilometer in China
and India, respectively. Average life expectancy at birth is now 75.8
years, with the population aging rapidly--the current median age of
33.1 years has risen by 5.1 years since 1970. The aging is a result
of a number of factors--delay in childbirth as a result of increased
female participation in the work force, expanded use of
contraception, and higher life expectancy. Overall, population growth
has slowed to about 1.1 percent per year.
For purposes of comparison, from 1960 to 1990 the U.S. population
increased by 38 percent, while the population of the European Union
increased by 15.8 percent. Projections through 2020 show a similar
disparity: the United States is projected to grow by 29 percent, and
the European Union by only 2.6 percent.
The geographic distribution of the population has significant bearing
on the global warming issue. For example, more and more people are
moving to the drier, warmer climate of the Sunbelt. Nine of the
twelve fastest-growing U.S. metropolitan areas in 1990 were located
in Florida. In most of the nation's coastal areas, population growth
has been positive and generally very large (Figure 2-3). For
instance, from 1970 to 1990, the population along the Southeast
Atlantic coast grew by 74 percent. Overall, 110 million people live
in these coastal areas, with densities exceeding 192 people per
square kilometer in 20 percent of these counties, and densities in
the urban cores of some of these areas exceeding 3,800 people per
square kilometer. Studies conducted by the U.S. government
anticipate a 15 percent increase in coastal population over the next
two decades, concentrated in California, Florida, and Texas.
This pattern of growth has resulted in over 50 percent of the
population living in metropolitan areas with more than one million
people--up from 29 percent in 1950. Despite this growing trend toward
urbanization, the population densities in U.S. metropolitan areas
are far lower than in metropolitan areas around the world. For
example, the ten largest European cities on average have population
densities four times greater than the ten largest U.S. cities. The
relatively low densities in the United States result in relatively
high energy use per capita, leading, for example, to more
energy-intensive transport.
U.S. Natural Resources
The natural resources of the United States are vast and varied. Its
diverse climate zones, topography, and soils support many ecological
communities and supply resources for many human uses. The nature and
distribution of these resources have played a critical role in the
development of the U.S. economy and, therefore, have influenced the
pattern of U.S. greenhouse gas emissions.
Land Resources
The United States has a total land area of approximately 931 million
hectares (2.3 billion acres). The state of Alaska alone has a land
area of approximately 166 million hectares (410 million acres).
Because Alaska is so large, and its land-use patterns differ
significantly from those in the 48 contiguous states and Hawaii,
Alaskan land use is treated separately in this report.
About 77 percent, or 600 million hectares (1.5 billion acres), of
U.S. land in the contiguous states is privately held; another 2
percent is owned by state or local governments. These together are
referred to as nonfederal lands. Alaska has 87.4 million acres of
nonfederal lands. The U.S. government owns about 263 million
hectares (650 million acres), or 31 percent of the contiguous land
area (Figure 2-4). In addition, federal lands include 131 million
hectares (323 million acres) in Alaska.
Although the private sector has played a primary role in developing
and managing U.S. natural resources, federal, state, and local
governments have also been important in managing and protecting these
resources through regulation, economic incentives, and education.
Governments also manage lands set aside for forests, parks, wildlife
reserves, special research areas, recreational areas, and in
suburban/urban open spaces.
Of U.S. nonfederal lands in the contiguous 48 states, about 155
million hectares (382 million acres) are cropland, 51 million
hectares (125 million acres) are pasture land, 162 million hectares
(399 million acres) are range, and 160 million hectares (395 million
acres) are forest land. There are approximately 36 million privately
owned acres enrolled in the Conservation Reserve Program; these
include highly erodible lands planted to perennial grasses or trees.
Developed nonfederal lands (including transportation routes, cities,
towns, and villages) now encompass 37 million hectares (92 million
acres)--an increase of 18 percent in the past decade.
In Alaska, nonfederal land use in 1994 included 0.05 million hectares
(0.13 million acres) of cropland, 21 million hectares (52 million
acres) of wetlands, and 6 million hectares (15 million acres) of
grazing lands, comprised of range, pasture, and tundra. Federal land
use included 31 million hectares (77 million acres) of forest, 63
million hectares (155 million acres) of wetlands, and 37 million
hectares (91 million acres) of tundra.
Forests
Forest land offers a significant sink for greenhouse gases, but may
also be highly vulnerable to changes in the climate system. U.S.
forests vary from the complex juniper forests of the arid interior
West to the highly productive forests of the Pacific Coast and the
Southeast. Forest land in the contiguous United States has increased
since the 1960s, from 251 million hectares (620 million acres) to 298
million hectares (737 million acres) in 1992. Of this 1992 total, 198
million hectares (489 million acres) were timberland, 80 percent of
which is privately owned.
Management inputs over the past several decades have been gradually
increasing production of marketable wood in U.S. forests. The United
States currently grows more wood than it harvests, with a growth-to-
harvest ratio of 1.37. This ratio reflects substantial new-forest
growth.
Grazing Lands
Grazing lands, including both range and pasture, are environmentally
important to the United States. They are the single largest land use
and thus have the potential to absorb significant quantities of
greenhouse gases. They also include major recreational and scenic
areas, serve as a principal source of wildlife habitat, and comprise
a large area of the nation's watersheds. Like forest ecosystems,
these ecosystems are vulnerable to rapid climate changes,
particularly shifts in temperature and moisture regimes. Range
ecosystems are more resilient than forest ecosystems, however,
because of their ability to sustain long-term droughts. Long-term
management of grasslands can greatly increase the carbon held in
these soils and thus can increase the carbon "sink."
Range ecosystems are any of a number of different communities,
usually denoted by the dominant vegetation. They are generally
managed by varying grazing patterns, by using fire to shift species
abundance, and by occasionally disturbing the soil surface to improve
water infiltration. Pasture land, in contrast, is a grazing ecosystem
that relies on more intensive management inputs, such as fertilizer,
chemical pest management, and introduced or domesticated species.
Range accounts for 161 million hectares (399 million acres), while
nonfederal pasture land accounts for 51 million hectares (125 million
acres). U.S. pasture land includes native grasslands, savannas,
alpine meadows, tundra, many wetlands, some deserts, and areas seeded
to introduced and genetically improved species.
The total area of nonfederal pasture and range declined by 7 percent,
approximately 6 million hectares (16 million acres), between 1982 and
1992. Most of this land was converted to urban and suburban land
uses. The reasons for the decline in forested grazing lands are
decreasing demand for livestock, as reflected in static prices for
animals and animal fiber; conversion to shorter-rotation forests,
which have reduced the quality of available forage; and reduced
grazing on hilly terrains due to the resulting vulnerability to soil
erosion.
Approximately 13 million hectares (33 million acres) of range and
pasture are still in a highly erodible state due to sheet and rill
erosion, and an additional 15 million hectares (38 million acres) are
highly erodible due to wind erosion. Nevertheless, the general
condition of grazing lands, both range and pasture, has been
improving over the past twenty years.
Climate change would decrease the productivity of grazing lands, but
could actually benefit their overall ecological condition. Warmer and
drier conditions may adversely affect the land at first. As extreme
drought continues, however, lack of easily available water could
result in reduced grazing, which could allow the land to recover.
Agricultural Land
The United States enjoys a natural abundance of productive
agricultural lands and a favorable climate for producing food crops,
feed grains, and other agricultural commodities, such as oil seed
crops. The area of U.S. cropland has declined by 9 percent in the
past decade--from 170 million hectares (420 million acres) to 155
million hectares (382 million acres)--as conservation programs for
the most environmentally sensitive and highly erodible lands have
removed approximately 16 million hectares (39 million acres) from
cropping systems.
Although the United States harvests about the same area as it did in
1910, it feeds a population that has grown by two and one-half times
since then, and its food exports have expanded considerably. This
heightened efficiency of U.S. agriculture is depicted in Figure 2-5,
which shows the yields of three major U.S. agricultural crops.
Climate change could enhance agricultural productivity in some areas.
Experimental results suggest that under a doubling of atmospheric CO2
and ideal water and nutrient conditions, corn, sugar cane, and
sorghum yields may increase by slightly less than 20 percent and
wheat, soybean and rice yields may increase by 20--60 percent.
Between 1947 and 1989, the total output of livestock and livestock
products rose 1.8 times, while during the same period production per
unit of breeding stock rose 2.2 times. The total number of cattle
peaked at 132 million head in 1975 and declined to 100 million head
in 1992. Sheep numbers over the past two decades have varied from 8.5
million head in 1977 to 7.7 million head in 1992. This reflects the
significant decline in average beef and lamb consumption per capita
in recent years.
Ruminant animals, such as cattle and sheep, produce significant
quantities of methane as part of their digestive process. The
breakdown of livestock manure is another source of methane. This gas
is second to carbon dioxide as a major contributor to global warming.
Wetlands
Wetland ecosystems, a substantial source of methane, represent some
of the more biologically important and ecologically significant
systems on the planet. They represent a boundary condition
("ecotone") between land and aquatic ecosystems. As such, they
provide habitats for many types of organisms (both plant and animal);
serve as diverse ecological niches that promote preservation of
biodiversity; are the source of economic products for food, clothing,
and recreation; trap sediment, assimilate pollution, and recharge
ground water; regulate water flow to protect against storms and
flooding; anchor shorelines; and prevent erosion. A wide variety of
wetland types exists in the United States, ranging from
permafrost-underlain wetlands in Alaska to tropical rain forests in
Hawaii.
Wetland ecosystems are highly dependent upon upland ecosystems and
are thus vulnerable to changes in the health of the upland ecosystems
as well as to environmental change brought about by shifts in climate
regimes. Coastal wetlands may be drowned by a rising sea and may be
unable to migrate inland because of human settlements. Prairie
potholes and riparian wetlands may decrease in dry areas made even
drier by changing climate. Tundra wetlands will shrink as
temperatures increase and allow the permafrost to thaw and drain.
Since the nation's founding in the eighteenth century, the
continental United States has lost 47 million of its original 89
million hectares (221 million acres) of wetlands. The data suggest
that the pace of wetland loss has slowed considerably in the past two
decades. For example, while net wetland losses from the mid-1950s to
the mid-1970s averaged 185,000 hectares (458,000 acres) per year, the
losses declined to about 117,000 hectares (290,000 acres) per year
from the mid-1970s to mid-1980s. Agricultural uses have accounted
for about 54 percent of wetland loss since the colonial period of our
nation's history, and, according to the U.S. Department of the
Interior, a significant additional share was lost as a result of
federal flood control and drainage projects. The reduced rate of
wetland loss since the mid-1980s is attributable to a combination of
government programs and low crop prices, which have reduced
conversions of wetlands to agricultural uses. Future losses from such
conversions are likely to be even smaller, as the United States
implements a "no net loss" policy for wetlands, a goal embraced in
1989.
Alaska's 71 million hectares (176 million acres) of wetlands easily
exceed the 42 million hectares (104 million acres) of wetlands in the
continental United States. Many of these areas are federally owned,
although precise figures are not available. Total wetland losses in
Alaska have been less than one percent since the mid-1800s, although
in coastal areas they have been higher.
Biological Resources
During the past twenty years, we have become more aware of the
reduction in the diversity of life at all levels, both within the
United States and worldwide. Warmer temperatures may exacerbate this
trend by shifting climate zones faster than ecosystems can migrate.
To better understand and catalogue both previous and future changes,
the United States has begun a comprehensive, nationwide survey of its
biodiversity, including its wildlife, called the National Biological
Survey.
Information on endangered species is already available through
various sources. In 1991, the U.S. government added 71 domestic
species to the Threatened and Endangered Species List, for a total of
668 species. Some 4,000 species remain candidates for listing. A 1990
assessment of recovery status for listed species revealed that 38
percent are declining, 10 percent are improving, 31 percent are
stable, 2 percent are extinct, and 19 percent are of unknown status.
Of the U.S. plant and animal species listed as threatened or
endangered in 1990, fully 40 percent are plants, and slightly more
than 10 percent are mammals, with approximately equal proportions
(about 14 percent) of birds, fish, and invertebrates, and a lesser
percentage (7.3 percent) of reptiles and amphibians.
Water Resources
The development of water resources has been key to the growth and
prosperity of the United States. Abundant and reliable water systems
have enabled urban and agricultural centers to flourish in arid and
semi-arid regions of the United States. For instance, between 1954
and 1992, irrigated agricultural land more than doubled, from 12
million hectares (29 million acres) to 25 million hectares (62
million acres).
Currently, most of the nation's freshwater demands are met by
diversions from streams, rivers, lakes, and reservoirs and by
withdrawals from ground-water aquifers. Even though total withdrawals
of surface water more than doubled from 1950 to 1980, they remained
less than 21 percent of the renewable supply in 1980. However, some
areas of the country still experience intermittent water shortages
during periods of drought.
In the arid sections of the western United States, there is
increasing competition for water--not only from traditional
agricultural and hydropower sources, but also for drinking water in
growing urban areas, American Indian water rights, industry,
recreation, and support of natural ecosystems. The flows of many
streams in the West are fully allocated to current users, limiting
opportunities for expanded water use by major new facilities.
Recently enacted state legislation adopts a market- based approach to
water pricing and allocation, thus offering the potential to
alleviate some effects of projected shortfalls. Also pertinent is the
federal government's insistence that certain minimum-flow
requirements be met to preserve threatened and endangered species.
Potential climate changes, including changes in the periodicity and
frequency of precipitation and rising temperatures, may have a
significant effect on water resources and resource infrastructure.
Energy Resources
The United States has vast resources of fossil fuels (Table 2-1).
Coal, which has the highest emissions of greenhouse gases per unit of
energy, is particularly abundant, with current recoverable reserves
totaling about 265 billion short tons. The vast majority--88.9
percent--of this figure is bituminous coal. Lignite and anthracite
coal provide 9.5 and 1.5 percent of total coal reserves,
respectively.
Government estimates suggest that other undiscovered economically
recoverable energy resources in the United States include 145.6
billion barrels of crude oil and 1,265.8 trillion cubic feet of
natural gas as of January 1, 1992. Proved reserves in the same year
were 23.7 billion barrels for oil and 165 trillion cubic feet for
natural gas. Proved reserves of oil have been declining ever since
the addition of reserves under Alaska's North Slope in 1970. U.S.
energy resources also include some 120 million kilograms (265 million
pounds) of uranium oxide, recoverable at $14 per kilogram ($30 per
pound) or less.
Knowledge of energy resources is important for placing the climate
change issue in context. The abundant fossil fuel resources of the
United States have contributed to low prices and relatively
energy-intensive activities. Concerns about global climate change may
make these resources relatively less attractive than renewable
resources or other forms of energy that produce lower greenhouse gas
emissions.
The U.S. Economy
The United States can be characterized most accurately as a mixed
economy. Some economic activity is carried out by private decision
makers (e.g., companies and consumers) and organized in markets, and
other economic activity is carried out by federal, state, and local
governments. Much of the private-sector market activity in the U.S.
economy is subject to some sort of government action or oversight,
such as that provided by the antitrust division of the U.S.
Department of Justice.
Government and the Market Economy
Several principles, institutions, and technical factors have
contributed to the evolution of America's mixed economy. The first of
these is the respect for individual rights, including the right to
own and use private property to one's own advantage.
The U.S. economic system is also underpinned by a belief that
voluntary exchange is the most efficient means of organizing economic
activity. Put another way, in the absence of "market failures,"
relative prices would ideally be the sole basis on which economic
agents within the U.S. economy would make decisions about production
and consumption. Combined with a system of well-defined and
well-protected private-property rights, the price system would lead
to an allocation of the resources of the U.S. economy that produces
the greatest possible social welfare.
However, markets do fail. The production of some goods and services
creates costs or benefits that are not captured by the price system,
causing too much or too little of the good or service to be produced
to maximize social welfare. In such cases, the U.S. government has
intervened to promote a more socially beneficial allocation of
resources.
For instance, the U.S. government (as well as state and local
governments) intervenes in the market to provide for public goods,
such as national defense and public infrastructure. Another common
reason for government intervention in the market is the presence of
externalities, which exist when the social costs of an activity
differ from its private costs. For example, vehicle owners bear only
part of the costs of emissions from motor vehicles; other members of
society and the environment bear the rest in the form of poor air
quality. As a practical matter, it is very difficult to establish
accurately the cost of the externality in order to internalize it by
a fee, a tax, or a regulation. Government intervention may include
limiting the physical quantity of pollution that individuals may
produce, or charging polluters a fee for each unit of pollution
emitted.
In addition to providing public goods and attempting to mitigate the
effects of externalities, the federal government transfers wealth
among various members of the U.S. society for social, cultural, or
political purposes. Such transfers include commodity support to
agricultural producers, and income maintenance and health-care
provisions for low- income families.
While the role of government in the U.S. economy is large, many
government interventions are intended to facilitate or support
well-functioning markets. By protecting property rights, producing
such public goods as roads and other types of infrastructure,
reducing externalities, and ensuring a minimum standard of living for
all of its citizens, the U.S. government fosters an environment in
which market forces can operate.
Finally, the federal government itself is a source of imperfection in
the U.S. economy. Over time, the government has created barriers
through its regulatory and fiscal processes that impede the smooth
functioning of markets, leading to wasteful inefficiencies.
Composition and Growth
The willingness of U.S. policymakers, the business community, and the
public to tackle more long-run and strategic environmental issues,
such as climate change, is influenced by the health of the economy.
A robust economy encourages this type of forward thinking, as
concerns about unemployment and growth lessen.
At the same time, policies to reduce greenhouse gases are likely to
benefit some parts of the economy, while adversely affecting others.
For instance, the current economic health and activities of the
energy-producing and -consuming sectors, the international trade
situation, and the state of the U.S. budget deficit are all important
factors in shaping U.S. climate change policies.
From 1960 to 1993, the U.S. economy grew at an average annual rate of
3 percent, raising the real gross domestic product (GDP) from nearly
$2 trillion to over $5 trillion (in 1987 dollars). With population
growth averaging 1.1 percent over the same period, this meant an
annual increase of approximately 1.8 percent in real GDP per capita,
from $10,903 in 1960 to $19,874 in 1993 (in 1987 dollars).
Employment over this period almost doubled--from 65 million to 120
million--as the labor force participation rate rose from 59 to 66
percent, with the largest growth in the work force attributed to
women.
This rapid growth has been led by the U.S. service sector, which
includes communications, utilities, finance, insurance, and real
estate. Between 1960 and 1993, this sector expanded from 28.8 percent
of the economy to 36.5 percent. Employment in the service sector
nearly tripled, while employment in industries that might be directly
associated with the climate change issue (agriculture, mining,
forestry, and fisheries) declined by 287,000 full- time equivalents
(Figure 2-6).
To a large extent, pollution control expenditures move with the
economy, with increases in such expenditures during boom times and
reductions during recession. Nevertheless, real abatement
expenditures have increased as a percentage of GDP. From 1972 to
1992, pollution abatement and control expenditures rose from $46
billion to $88 billion per year, or from 1.5 to 1.8 percent of GDP.
The economic growth over the previous thirty years masks several
economic problems that may influence the design and implementation of
U.S. climate policy. Most important, there were serious structural
difficulties in the U.S. economy, evidenced by the low growth in
productivity over the last two decades. Annual productivity growth
averaged 3.1 percent from 1947 to 1973, but only 1.0 percent since
then.
The increasing dependence of the United States on trade, coupled with
weak foreign economic performance over the past few years, has
increased the influence of external events on U.S. economic
performance. During 1991--93, the country experienced the worst
foreign economic performance in thirty years. In the 1990s, growing
U.S. reliance on foreign computers led a surge of imported capital
goods, with overall imports in 1993 at their highest percent of GDP
since World War II (13.2 percent).
In addition, from 1989 to 1993, the U.S. economy grew by only 1.8
percent annually, with the civilian unemployment rate above 6 percent
since November 1990 (but attaining 6 percent in May 1994). The
"recovery" that began in 1991 has been slow by historical standards.
The U.S. economic expansion consolidated in 1993, setting the stage
for sustained growth in 1994. In the first quarter of 1994, real GDP
grew at the long-run historical average rate of 3 percent. The
outlook for the U.S. economy is for moderate, but steady economic
growth over the mid-1990s, with a projected annual growth in GDP of
2.5 to 3 percent. This growth should be sufficient to reduce
unemployment to about 5.5 percent by 1999, while producing healthy
increases in real disposable income and increased real wages.
The U.S. Federal Budget
Since 1970, federal outlays for natural resources and the environment
have increased sevenfold. Federal discretionary outlays for the
management of the environment and natural resources totaled $31.3
billion in 1993 and $33.6 billion in 1994. The proposed increase, to
$35.2 billion in 1995, evidences a deep and continuing commitment to
environmental protection, given that overall discretionary federal
outlays proposed for 1995 are unchanged from 1993 actual spending.
The projections for tight federal budgets in the foreseeable future
are directly related to deepening public concern over budget
deficits. The federal budget has been in deficit for thirty-three of
the past thirty-five years, with the peak deficit in 1992 of $290
billion. Until 1975, the ratio of deficit to GDP was stable or
falling. However, from 1975 through 1992, this ratio began an upward
trend, which fluctuated with the business cycle (Figure 2- 7). Until
the 1980s, the ratio of public debt to GDP also was stable or
falling. From 1980 through 1992, however, this ratio dramatically
increased.
Changes in the tax code and U.S. budget outlays enacted in 1993,
along with projections for stable growth, are expected to reverse the
trend of ever- increasing deficits, while reducing the ratio of the
deficit to GDP to about 2 percent by 1995.
Growing political pressure for substantial reductions in the U.S.
deficit has recently been reflected in procedures that make it
difficult for new or expanded programs to pass the Congress. In 1990
Congress passed the "pay-as-you-go" provisions of the Omnibus Budget
Reconciliation Act, which created caps on total discretionary
spending. Thus, any increase in such spending passed by Congress must
be offset by decreases elsewhere. The same process applies to passage
of new mandatory spending programs, which can be offset either by
cuts in existing spending or with tax increases. In light of these
budget-constraining systems and a federal budget that is growing only
slightly in nominal terms, new programs, such as those that might be
needed to respond to The Climate Change Action Plan, will be in
direct competition for funds from a host of existing and other new
programs.
National Revenue Structure
Federal, state, and local governments in the United States collect
most of their general revenue from taxes on income, retail sales, and
property. Environmental programs are mostly funded through federal
agencies, but state and local governments contribute substantially.
Federal Revenue
The major sources of federal government revenue are individual and
corporate income taxes (Table 2-2). Indeed, the federal government
raises more money from income taxes than state and local governments
raise from all taxes combined.
The U.S. government levies no property or general sales tax, but does
collect sales taxes on selected excises, such as motor fuel and
alcoholic beverages. The government also earns revenues from
environmental and natural resource management. In 1991, it collected
over $8.4 billion in revenues from such activities as leasing and
extracting natural resources on federal lands, taxes on emissions of
chlorofluorocarbons, and penalties for oil spills.
State Revenue
Sales taxes are the largest single source of state revenue (Table
2-3). Almost all states also administer income taxes, but their
aggregate collections are much smaller than federal income tax
revenue. All fifty of the states receive revenue from sales or gross
receipts taxes, and only five do not impose a general sales tax.
States also levy excise taxes on motor fuel and alcohol.
Local Revenue
Property taxes are by far the major source of local tax revenue
(Table 2-2). It is not uncommon for cities to levy general sales and
local income taxes, but in many cases the taxes are limited to
coverage of employee payroll, rather than taxes on income from all
sources. Local income taxes are often administered locally, whereas
local sales taxes are usually "piggybacked" on the administration of
state sales taxes. Relatively high local tax rates are often a key
factor in the movement of taxpayers from cities into suburbs, where
their energy consumption for transportation and heating is generally
higher.
U.S. Energy Production and Consumption
The United States is the world's largest energy producer and
consumer. The nation's patterns of energy use are determined in part
by its economic growth, land area, climate regimes, low population
density, and significant indigenous resources. Much of the
infrastructure of U.S. cities, highways, and industries was developed
in response to abundant and relatively inexpensive energy resources.
Figure 2-8 depicts the energy flows through the U.S. economy in 1992.
The effects of global warming are likely to change patterns of our
nation's use of energy. For instance, regional shifts in economic
activities and population related to global warming will affect the
U.S. energy mix, because different regions of the country rely on
different mixes of energy resources to generate power and meet other
energy needs. Furthermore, activities to mitigate greenhouse gas
emissions and adapt to any negative effects of global warming that
remain will surely be based on substantial involvement of the energy
sectors. In general, this involvement is likely to take the form of
changes in the energy mix or technologies used to produce
commodities--or even in the types of commodities that are
produced--in residential and commercial energy use, and in vehicles
and the fuels that power them. Changes in the behavior of energy
users of all types are also likely outcomes of mitigation or
adaptation activities.
Energy Production
Coal, natural gas, and petroleum have long comprised the bulk of U.S.
energy production since 1960, accounting for 96.1 percent of
production in 1960 but falling to 85.5 percent in 1993. The
commercial introduction of nuclear electric power and expanded
hydroelectric generation has displaced some of the fossil fuel
production (Figure 2-9), but further displacement is not expected to
continue, given public opposition to nuclear power and to further
damming of rivers. Energy production from other renewable resources,
such as geothermal, solar, wind, and waste products, is still a small
share of the total.
Before 1970, the United States imported a small amount of energy,
primarily in the form of petroleum. Lower acquisition costs for
imported crude oil in the early 1970s, however, put U.S. oil
producers at a comparative disadvantage. By 1971, this gap led to a
divergence in trends of energy production and consumption.
Domestic oil production is projected to continue to decline, due to
depletion of existing reserves, with few new discoveries. Oil
production may increase slightly after 2006, however, in response to
rising prices and technological gains. Even so, as the increase in
oil consumption continues to outpace production, U.S. net oil imports
are expected to rise to 60 percent of U.S. consumption by 2010, up
from about 44 percent in 1993 (U.S. DOE/EIA 1994b).
Coal is the largest source of domestic energy. With expected
increases in demand for electric power production and exports, coal's
share of U.S. energy production is projected to increase from 31
percent in 1991 to 35 percent in 2010.
Because of the availability of lower-cost sources, domestic
production of natural gas--the second largest source of domestic
energy supply--is expected to reverse its historical decline.
However, the share of energy production contributed by natural gas is
expected to decrease from 29 percent in 1993 to 27 percent in 2010.
Between now and 2010, emerging renewable sources-- especially solar,
wind, biomass, geothermal, and biofuels, which currently contribute a
scant 0.2 percent to domestic energy supply--are expected to grow
steadily at rates exceeding those of other sources. In addition,
efficiency improvements will yield increases in hydroelectric energy
production.
Energy Consumption
On the consumption side, rapid economic growth, even when combined
with the decreasing energy intensity of the transportation and
buildings sectors, resulted in an 80 percent increase in energy
demand from 1960 to 1979. Most of the increased demand was met by oil
imports and by increased consumption of coal and natural gas. Demand
dampened during and after the international oil price shocks in
1973--74 and 1979--80, with some significant declines in oil use.
In 1986, real crude oil prices fell dramatically to one-third of peak
rates during the 1979--80 supply disruption and were less than peak
rates during the 1973--74 disturbance. Since 1986, crude oil prices
and retail oil prices have fluctuated. While rising from 1980 through
1988, U.S. oil consumption has leveled off as oil prices recovered
and U.S. economic growth slowed.
Growth in the economy, population, and vehicle miles traveled could
have propelled U.S. energy consumption far beyond its nearly 100
percent growth since 1960, if not for impressive reductions in the
energy intensity of the U.S. economy. There has been a 27 percent
decrease in energy use per dollar of GDP from its 1970 peak, with
intensity basically flat after 1986. Most of these efficiency
improvements have come from the industrial sector, although the
household and transportation sectors also experienced gains. In terms
of the level of energy intensity relative to other countries, the
United States ranks slightly behind the Organization of Economic
Cooperation and Development's (OECD's) average in energy use per
dollar of GDP--0.43 kilograms of oil equivalent per dollar of GDP,
versus 0.41 for OECD--and significantly behind Norway and Japan. In
contrast, Canadian energy intensity is considerably higher than that
of the United States, at 0.53 kilograms of oil equivalent per dollar
of GDP.
Turning to consumption by sector, in 1993, the generation,
transmission, and distribution of electricity accounted for 20.54
quadrillion BTUs (quads) of energy consumption, leaving 63.2 quads
for direct consumption by end users. Industry and transportation
consumed nearly three-quarters of this direct energy, while the
residential and commercial sectors used 27 percent.
Industrial Energy Use
Comprised of manufacturing, construction, agriculture, and mining,
the industrial sector accounts for slightly over one-third of total
energy use in the United States, and approximately 33 percent of
total U.S. carbon emissions in 1990. Industry's share of end-use
energy consumption has dropped significantly over the past thirty
years. In 1960, industrial energy use accounted for 46 percent of all
energy consumed; by 1972, it had fallen to 42 percent, and by 1990,
to 36.8 percent.
Similarly, from 1972 to 1990, industrial energy intensity (energy use
divided by industrial contribution to GDP) improved by 35.3 percent.
Approximately two-thirds of the decline in intensity over the period
1972--90 was due to structural shifts, such as the changing array of
products that industry produced. Since 1972, the energy savings due
to reductions in energy intensity has grown to more than 12
quadrillion BTUs annually (Figure 2- 10).
The manufacturing sector has steadily reduced its energy intensity
over the past two decades, although the rate of improvement has
slowed since 1985, when energy prices fell. Of the fifteen major
energy- consuming industry groups in the manufacturing sector, most
continued to reduce their energy intensity between 1980 and 1991.
Residential and Commercial Energy Use
The number, size, and climatic distribution of residential and
commercial buildings, as well as the market penetration of heating
and cooling technologies and major appliances, are good indicators of
energy consumption and greenhouse gas emissions associated with
residential and commercial activities. Today, these activities
account for roughly 35 percent of the U.S. carbon emissions.
The United States has about 94 million housing units, approximately
half of which are detached and occupied by a single family. Since
1960, the average number of people per residence has declined from
3.33 to 2.63. As a consequence, the average heated space per person
has increased to 56 square meters (602 square feet) in 1990, compared
to 50 square meters (534 square feet) in 1980.
In addition, during this period the penetration of major heating and
cooling technologies and of major energy-using appliances increased
substantially. By 1990, nearly all U.S. households had space heating,
water heating, refrigeration, cooking, and color television sets;
about 68 percent had some form of space cooling; 75 percent had
clothes washers; and roughly 50 percent had clothes dryers and
dishwashers. On the other hand, this period has seen large gains in
energy efficiency, which, in spite of the growth in appliance
penetration and heating/cooling space per person, have resulted in a
25 percent drop in average household energy use-- from 138 million
BTUs per household in 1978 to 101 million BTUs in 1987. On net, with
the substantial increase in the number of U.S. households, overall
energy use in this sector has remained roughly stable since the
mid-1970s.
The commercial sector has been the fastest-growing economic sector in
the United States. In 1990, there were about 70 billion square feet
of commercial building space, which encompasses all nonresidential,
privately owned, and public buildings. Virtually all commercial
buildings are heated, and over 80 percent are cooled. In addition,
the past decade has seen a major increase in the use of computers and
other energy-consuming office equipment. Rapid growth in this sector
has substantially increased the energy services required by
commercial buildings, but, as in the residential sector, substantial
efficiency gains have reduced the net increases in energy demand and
carbon emissions.
Transportation Energy Use
The U.S. transportation system has evolved into a multimodal system,
including highway, mass transit, air, rail, waterborne, and pipeline
transport (Figure 2-11). The current U.S. surface transportation
system is dominated by automobiles and light trucks, with the latter
now comprising almost 40 percent of new passenger vehicle purchases.
In 1990, the highway share of passenger travel was 85 percent, with
most of the remainder accounted for by air travel (11 percent). In
contrast, the share of bus and rail was 4 percent.
Over 3.1 trillion ton-miles of freight are moved in the United States
each year. The predominant mode of intercity freight is rail,
followed by waterways, highways, pipelines, and air. Although the
trend is now reversing, between 1960 and 1990, the number of railroad
cars in use declined, whereas the number of motor vehicles and air
carriers increased dramatically, and the number of water-transport
vessels and oil pipelines grew steadily.
Motor vehicle ownership, use, and efficiency provide good indicators
of the nation's energy consumption in the transportation sector,
which accounts for approximately one-third of U.S. greenhouse gas
emissions. Between 1960 and 1991, the number of cars and trucks
registered in the United States more than doubled--from 74 million to
192 million. Rising incomes have much to do with this growth in
vehicle ownership. Population growth has been important as well.
Since 1960, the driving-age population has grown from 121 million to
192 million in 1990, while licensed drivers have increased from 72
percent of this group to 87 percent over the same period.
A 50 percent increase in vehicle kilometers traveled since 1969 has
been partly offset by a 34 percent decrease in the amount of fuel
consumed per kilometer. In 1990, personal passenger vehicles in the
United States traveled a total of 2.4 trillion kilometers (1.6
trillion miles), using 273 billion liters (82 billion gallons) of
fuel, with an average fuel efficiency of almost 8.9 kilometers
traveled per liter (21 miles per gallon) of fuel. By contrast, in
1969 U.S. personal-passenger vehicles traveled a total of 1.6
trillion kilometers (1 trillion miles), using 242 billion liters (64
gallons) of fuel, with an average fuel efficiency of about 5.7
km/liter (4 mpg).
The causes for the rapid rise in vehicle miles traveled are many,
although their relative importance is unclear. In 1990, there were
more personal vehicles than licensed drivers (1.02 vehicles per
licensed driver), compared to 0.74 vehicles per licensed driver in
1960. This increase in ownership rates translates into increased
vehicle use by reducing people's need to carpool or use public
transportation. And these vehicles are being driven farther--up from
5,906 kilometers (9,510 miles) in 1960 to 7,415 kilometers (11,940
miles) on average in 1990. Greater vehicle ownership and use are
related to changing patterns of land use, the changing composition
and location of work and shopping centers, reduced costs of driving,
increased labor force participation of women, and a host of other
factors.
U.S. Governing Institutions
The political and institutional systems participating in the
development and protection of the nation's environmental and natural
resources are as varied as the resources themselves. These systems
span federal, state, and local government jurisdictions, and include
legislative, regulatory, judicial, and executive institutions.
The U.S. government is divided into three separate branches: the
executive branch, which includes the executive office of the
President, departments, and independent agencies; the legislative
branch (the U.S. Congress); and the judicial branch (the U.S. court
system). There is a distinct separation of powers in this tripartite
system--quite different from parliamentary governments.
Federal Departments and Agencies
There are fourteen executive departments in the executive branch,
seven agencies, and a host of commissions, boards, other independent
establishments, and government corporations. The traditional
functions of a department or agency are to help the President propose
legislation; to enact, administer, and enforce regulations and rules
implementing legislation; to implement executive orders; and to
perform other activities in support of the institution's mission,
such as encouraging and funding research, development, and
demonstration of new technologies.
No single department, agency, or level of government in the United
States has sole responsibility for the panoply of issues associated
with climate change. In many cases, the responsibilities of federal
agencies are established by law, with limited administrative
discretion. At the federal level, U.S. climate change policy is
determined by an interagency coordinating committee, chaired from
within the Executive Office of the President, and staffed with
members of the executive offices and officials from the U.S.
Departments of Energy, Transportation, Agriculture, Treasury,
Commerce, Interior, and State, as well as the U.S. Environmental
Protection Agency.
The U.S. Congress
Responsibility for climate change and other environmental and natural
resource issues at the national level also resides with Congress,
which is the legislative branch of the U.S. government. Congress
influences environmental policy through two principal vehicles: the
creation of laws and the oversight of the federal executive branch.
Under its constitutional authority, the Senate must provide its
advice and consent before the United States can ratify international
treaties, such as the U.N. Framework Convention on Climate Change.
The U.S. Congress consists of two elected chambers, the Senate and
the House of Representatives, having generally equal functions in
lawmaking. The Senate has 100 members, two representing each state;
the House has 435 members, each of whom represents a district in a
state allocated by population. Less populated regions of the country,
therefore, have proportionately greater influence in the Senate than
in the House. Environmental proposals, like most other laws, may be
initiated in either chamber. After their introduction, proposals--or
"bills"--are referred to specialized committees and subcommittees,
where most legislative work takes place.
Committees and subcommittees hold public hearings on the bills to
receive testimony from interested and expert parties. After reviewing
the testimony, they deliberate and revise the bills. Committees then
submit the bills for debate by the full membership of that chamber.
Differences between bills originating in either the House or the
Senate are resolved in a formal conference between the two chambers.
To become a law, a bill must be approved by the majorities of both
chambers, and then must be signed by the President. The President may
oppose and veto a bill, but Congress may override a veto with a two-
thirds majority from each chamber.
State and Local Governments
States, localities, and even regional associations still exert
significant influence over the passage, initiation, and
administration of environmental, energy, natural resource, and other
climate-related programs. For example, the authority to regulate
electricity production and distribution lies with state and local
public utility commissions. In addition, the regulation of building
codes--strongly tied to the energy efficiency of buildings--is also
controlled at the state and local levels.
Each of the fifty states enjoys significant autonomy in its approach
to environmental regulation and management activities. States
implement federal laws by issuing permits and by monitoring
compliance with regulatory standards. States also generally have the
discretion to set standards more stringent than the national
standards. In addition to regulation, some states and localities have
developed programs that encourage energy efficiency and conservation
or otherwise mitigate projected levels of greenhouse gas emissions.
Local power to regulate land use is derived from a state's power to
enact legislation to promote the health, safety, and welfare of its
citizens. States vary in the degree to which they delegate these
"powers" to local governments, but land use usually is controlled to
a considerable extent by local governments (county or city). This
control may take the form of authority to adopt comprehensive land-
use plans, to enact zoning ordinances and subdivision regulations, or
to restrict shoreline, floodplain, or wetland development.
The U.S. Court System
The U.S. court system is also crucial to the disposition of
environmental issues. Many environmental cases are litigated in the
federal courts. The federal court system is three-tiered: the
district court level; the first appellate (circuit) court level; and
the second and final appellate level--the U.S. Supreme Court. There
are ninety-four federal district courts, organized into federal
circuits, and thirteen federal appeals courts.
Cases usually enter the federal court system at the district court
level. However, disputes between states may be brought directly
before the Supreme Court. In civil environmental cases, complaints
are brought on behalf of the government and are filed by the U.S.
attorney general. Any other person (regardless of citizenship) may
also file a complaint alleging a grievance.
Sanctions and relief in civil environmental cases may include
monetary penalties, awards of damages, and injunctive and declaratory
relief. For example, courts may direct that pollution cease, that
contaminated sites be cleaned up, or that environmental impacts be
assessed before a project proceeds. Criminal cases under federal
environmental laws may be brought only by the government (the
attorney general or state attorneys general). Criminal sanctions in
environmental cases may include fines and imprisonment.
Scientific Institutions
Climate change is a highly technical, scientific issue. Political
action, at any level, requires sound advice and information from the
scientific community. Thus, governments must have access to the best
scientific information available. The independent, congressionally
chartered National Academy of Sciences (NAS) and the National Academy
of Engineering (NAE) are important sources of high- level scientific
advice. The NAS is a key link between the academic and federal
research communities, convening special study groups. An example of
issues addressed is the identification of prudent actions that could
be taken to reduce greenhouse gases or adapt to global warming. NAS
and NAE panels are periodically requested by Congress or federal
science agencies to address global climate change issues. At present
the NAS is going through a transition to strengthen its ability to
provide scientific advice to the public sector that is both timely
and pertinent to policy decisions.
Organizing advice on climate change for the federal government is the
task of the newly established cabinet-level National Science and
Technology Council (NSTC). Chaired by the President, the Council was
created to coordinate research and development on science and
technology. One of the committees under the NSTC focuses exclusively
on environmental and natural resource issues. The largest and most
mature program under this committee is the U.S. Global Change
Research Program, described in depth in Chapter 6 of this report. A
high-ranking, private-sector committee has also been formed to
interact with the NSTC and enhance opportunities for public--private
partnerships. The President's Committee of Advisors on Science and
Technology provides the links to the private sector that will help
guide federal investments in science toward national goals.
U.S. Policies Related to Climate Change
U.S. climate change policies focus primarily on mitigating climate
change. Where mitigation strategies are infeasible, policymakers must
work to identify ways to adapt to those effects, so as to minimize
environmental and economic losses.
Agriculture and Land-Use Policies
For the past fifty years, agricultural and forestry policies have
increasingly reflected the principles of conservation and sustainable
use for food and fiber production. Legislation and public--private
partnerships have focused on protecting a productive resource base by
creating incentives to reduce soil erosion on crop, range, and
pasture lands; maintain or expand wetlands; enhance privately owned
wildlife habitat; and improve water quality.
U.S. policies to improve forest conservation on both public and
private lands involve initiatives for reforestation, improved harvest
systems, and the sustained use of all forest resources. In 1991, over
25 million trees were planted or improved in urban areas alone. In
1992, nearly $20 million was available to cost-share tree planting
and improvements in rural areas. The federal government also
encourages state foresters and private nonindustrial landowners to
develop forest stewardship plans before harvesting their timber.
Recently, the U.S. government adopted the principle of ecosystem
management for publicly owned forest lands, announced an end to
clearcutting as a standard harvesting practice on those lands, and
launched a major research effort focusing on ecosystem management.
The conservation title of the 1985 Farm Bill and its subsequent
amendments changed the priorities of U.S. federal soil- and
water-conservation agencies, of their state and local program
participants, and of farmers themselves. It accomplished this through
such programs as the Conservation Reserve Program and the
"Swampbuster" and "Sodbuster" provisions, by giving farmers
incentives to prevent pollution and conserve highly erodible lands.
The Conservation Reserve Program pays farmers for easements on
environmentally sensitive cropland, including farmed wetlands and
prior-converted cropland. The Swampbuster provision protects the
environmental values of wetlands by severely restricting the
conversion of wetlands to cropland. The Sodbuster provision reduces
the incentive for converting grasslands and forests to crop
production by requiring the use of conservation measures on all such
converted land.
Environmental Policies
In the twenty-four years since the first Earth Day, the United States
has struggled to achieve a balance between the protection of the
environment on the one hand, and the consumption of resources and
discharge of waste on the other. In particular, there has been a
tension between the use of energy that fuels our economy and the need
to protect our environment.
Until the late 1980s, U.S. environmental programs were largely
focused on directly controlling the environmental releases from the
energy-producing sector and heavy-manufacturing industries that have
historically used a significant amount of energy, such as the metal
production and pulp and paper industries.
From 1970 to 1990, the U.S. Congress enacted the Clean Air Act, the
Clean Water Act, and the Resource Conservation and Recovery Act,
which empowered the U.S. Environmental Protection Agency (EPA) and
other federal agencies to place significant environmental controls on
U.S. industries, in particular on the extraction, production,
distribution, and use of energy throughout our economy. During this
period, EPA directed industrial facilities to use "end-of- pipe"
pollution control technologies that often required significant
amounts of energy to operate.
In the latter half of the 1980s, the United States began to focus
more on preventing pollution and promoting energy efficiency than on
technologies that controlled the pollution after it had been
produced. For instance, EPA and the U.S. Department of Energy (DOE)
are now promoting and implementing a series of voluntary
energy-efficiency programs that encourage major U.S. companies to
reduce their electrical energy consumption at their facilities.
Besides preventing pollution, this reduced energy consumption can
result in substantial profits for program participants.
Another major shift in the direction of U.S. environmental policy
was a new emphasis on identifying effective policies for reducing
environmental pollution other than direct "command- and-control"
regulation. For instance, under the Clean Air Act Amendments of 1990,
EPA is working with utilities to curb sulfur dioxide levels through
an "allowance trading" system that allows them to buy and sell to
each other sulfur dioxide permits as a means of meeting requirements
for reducing emissions.
Energy Policies
DOE supports a broad range of energy technology research,
development, demonstration, and deployment programs. Virtually all of
the technologies that DOE is developing could lead to significant
reductions in greenhouse gases, especially beyond 2000. The Energy
Policy Act of 1992 has expanded these efforts and has authorized many
new initiatives. It particularly emphasizes measures likely to reduce
greenhouse gas emissions, such as expanded efficiency standards and
incentives, the accelerated development and deployment of
renewable-energy technologies, and the introduction of alternative
fuels in the transportation sector.
Transportation Policies
Traditionally, U.S. transportation policy has focused on promoting
commerce and trade, national security concerns, safety, and personal
mobility. Along with other factors, this focus has contributed to
the development of an extensive local and interstate highway network
and a widespread dependency on the automobile. While these original
goals are still highly valued, increasing concerns about the
environmental impacts of the construction and use of transportation
facilities have led policymakers to reevaluate traditional methods by
which to achieve transportation policy objectives. The result has
been an aggressive campaign by federal transportation officials to
encourage more effective use of the existing transportation system
and increased flexibility for state and local transportation
officials in deciding how to meet their citizens' demand for safe,
efficient, and environmentally friendly travel. Examples include
promoting carpools, the use of mass transit, and telecommuting over
single-passenger-vehicle travel.
Environmental concerns, including greenhouse gas emissions, have
emerged as a priority in U.S. transportation policy. Significant
federal efforts to limit the impacts of transportation on
environmental quality began in the 1960s, in response to concerns
about urban air quality and impacts of road construction on the
natural environment.
In the 1970s, the federal government established standards for
automotive fuel efficiency, based on the average fuel-efficiency
levels of all automobiles sold in the United States by each producer.
These norms, called the "corporate average fuel economy" (CAFE)
standards have risen from an initial level of 7.7. kilometers per
liter (18 miles per gallon) in 1978 to 12 kpl (27.5 mpg) in 1990. As
a result, U.S. average fuel efficiency has risen from about 9 kpl (14
mpg) in 1978 to 13 kpl (21 mpg) in 1990. Large increases in overall
vehicle miles traveled, however, have offset these gains in fuel
efficiency.
Recent legislation reflects a growing awareness of the environmental
implications of transportation policy. In 1991, the President signed
into law a major revision and updating of U.S. transportation law and
programs, called the Intermodal Surface Transportation Efficiency Act
(ISTEA), as well as a major revision to the Clean Air Act. Together,
these acts integrate environmental and transportation planning and
policymaking at the federal, state, and local levels, to an
unprecedented degree. For instance, state and local governments will
be considering congestion management and
transportation-demand-management strategies (including market
pricing), which will have the ancillary effect of reducing greenhouse
gas emissions.
The Clean Air Act Amendments of 1990 also set federal and state
agencies on a course to develop and promote alternative-fueled
vehicles. To address continuing air pollution problems in U.S.
cities, the Amendments called for tighter vehicle-emission standards
and other emission-reduction measures for areas violating the
National Ambient Air Quality Standard for ambient tropospheric ozone.
As a result, some cities and states--most notably California--have
instituted "low-emission-vehicle" programs, which require that a
small but growing portion of new-car sales be composed of these
vehicles. Alternative-fuel infrastructure and vehicle conversions are
also receiving a boost through the use of ISTEA funds. Some types of
alternative-fuel vehicles could result in lower emissions per mile.
Text Box: Clean Air Act Amendments
Implementation of the 1990 Clean Air Act Amendments achieves
substantial reductions in greenhouse gases and their chemical
precursors and contributes to the goals of the Action Plan by:
-- Directly reducing carbon dioxide as a result of more efficient
electricity generation.
-- Reducing U.S. emissions of volatile organic compounds, carbon
monoxide, and nitrogen oxides, which will curb ground-level ozone, in
addition to reducing emissions of the more familiar pollutants, such
as sulfur dioxide.
-- Promoting enhanced energy conservation and clean fuels, such as
natural gas.
-- Developing and implementing programs involving nonregulatory
approaches for the reduction of air pollutants, including CO2
emissions.
-- Requiring EPA to prepare national and international inventories
of methane, monitor and report CO2 emissions from certain stationary
sources, and develop a research program to measure, monitor, and
analyze air pollutants.
Text Box: The U.S. Energy Policy Act
Several titles of the U.S. Energy Policy Act (EPAct) are extremely
important to the overall U.S. strategy of reducting greenhouse gas
emissions.
-- Title I--The energy efficiency title establishes
energy-efficiency standards, promotes research and development of
energy-efficient technologies, promotes dissemination of
energy-saving information, and provides incentives for state and
local authorities to promote energy efficiency.
-- Titles III, IV, V, and VI--The alternative fuels and vehicle
titles provide monetary incentives, establish federal requirements,
and provide for research, design, and development of fuels and
vehicles that can reduce oil use and, in some cases, carbon emissions
as well.
-- Titles XII, XIX, XXI, and XXII--The renewable- energy title, the
revenue provisions, the energy and environment title, and the energy
and economic growth title promote increased research, development,
production, and use of renewable-energy sources and more
energy-efficient technologies.
-- Title XVI--The global climate change title provides for the
collection, analysis, and reporting of information pertaining to
global climate change, including a voluntary reporting program to
recognize utility and industry efforts to reduce greenhouse gas
emissions.
-- Title XXIV--This title facilitates efforts to increase the
efficiency and electric power production of existing federal and
nonfederal hydroelectric facilities.
-- Title XXVIII--This title streamlines licensing for nuclear
plants, which enables nuclear power to displace carbon-emitting
sources.
Text Box: Intermodal Surface Transportation Efficiency Act
The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991
provides for improved operation of the transportation system and
gives state and local governments increased flexibility in spending
federal funds for a variety of projects. that would help reduce
greenhouse gas emissions. For instance, state and local
transportation officials may redirect federal highway construction
funds toward the development of high-occupancy-vehicle (carpool)
lanes and transit-facilities. Additionally, ISTEA provides for
testing and implementing intelligent- vehicle and highway-system
technologies and services to reduce congestion, energy use, and
emissions. The Act also created the Congestion Management and Air
Quality Improvement Program to allow state and local officials to
direct transportation funds to help certain areas meet the standards
set by the Clean Air Act Amendments of 1990.
Chapter 3. Greenhouse Gas Inventory
Central to any study of climate change is the development of an
emission inventory that identifies and quantifies a country's primary
sources and sinks of greenhouse gases. The inventory process is
important for two reasons: (1) it provides a basis for the ongoing
development of a comprehensive and detailed methodology for
estimating sources and "sinks" of greenhouse gases, and (2) it
provides a common and consistent mechanism that enables all signatory
countries to the United Nations' Framework Convention on Climate
Change to estimate emissions and to compare the relative
contributions of different emission sources and greenhouse gases to
climate change. Moreover, systematically and consistently estimating
emissions at the national and international levels is a prerequisite
for evaluating the cost-effectiveness and feasibility of pursuing
possible mitigation strategies and adopting emission-reduction
technologies.
This chapter summarizes the sources and sinks of U.S. greenhouse gas
emissions. The methods used to estimate emissions and sinks, as well
as the uncertainties associated with using them, are reported in
Inventory of U.S. Greenhouse Gas Emissions and Sinks:
1991--1993, a supporting document to this Climate Action Report (U.S.
EPA 1994). Although estimates are provided for all four years, the
1990 estimates are considered the base year, because the Framework
Convention on Climate Change specifies that countries should submit
inventories of their greenhouse gas emissions for the year 1990.
The emission estimates presented here were calculated using the IPCC
Draft Guidelines for National Greenhouse Gas Inventories (IPCC/OECD
1994), to ensure that the emission inventories submitted to the
Framework Convention are consistent and comparable across sectors and
among nations. The United States has followed these guidelines,
except where more detailed data or methodologies were available for
major U.S. sources of emissions. In such cases, the United States
expanded on the IPCC Guidelines to provide a more comprehensive and
accurate account of U.S. emissions. Inventory of U.S. Greenhouse Gas
Emissions and Sinks for 1990- 1993 documents these sources, explains
the reasons for diverging from the IPCC Guidelines, and presents the
uncertainties associated with each emission estimate.
Recent Trends in U.S. Greenhouse Gas Emissions
Greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous
oxide (N2O), and ozone (O3). Chlorofluorocarbons (CFCs), a family of
human-made compounds, its substitute hydrofluorocarbons (HFCs), and
other compounds, such as perfluorinated carbons (PFCs), are also
greenhouse gases. In addition, there are other "photochemically
important" gases, such as carbon monoxide (CO), oxides of nitrogen
(NOX), and nonmethane volatile organic compounds (NMVOCs) that are
not greenhouse gases, but contribute indirectly to the greenhouse
effect. These are commonly referred to as "tropospheric ozone
precursors" because they influence the rate at which ozone and other
gases are created and destroyed in the atmosphere. For convenience,
all gases discussed in this chapter are generically referred to as
"greenhouse gases" (unless otherwise noted), although the reader
should keep these distinctions in mind. This chapter also reports
U.S. emissions of sulfur dioxide (SO2). Sulfur gases-- primarily
SO2--are believed to contribute negatively to the greenhouse effect.
Although carbon dioxide, methane, and nitrous oxide occur naturally
in the atmosphere, their recent atmospheric build-up appears to be
largely the result of human activities. This build-up has altered the
composition of the Earth's atmosphere and may affect future global
climate. Since 1800, atmospheric concentrations of carbon dioxide
have increased by more than 25 percent, methane concentrations have
more than doubled, and nitrous oxide concentrations have risen
approximately 8 percent (IPCC 1992).
And from the 1950s until the mid-1980s, when international concern
over CFCs grew, the use of these gases increased nearly 10 percent
per year. However, the consumption of CFCs is declining quickly, as
they are phased out under the 1987 Montreal Protocol on Substances
That Deplete the Ozone Layer. In contrast, use of CFC substitutes is
expected to grow significantly.
The current U.S. greenhouse gas inventory for 1990-- 93 is summarized
in Table 3-1. For the 1990 base year, total U.S. emissions were 1,444
million metric tons of carbon equivalent (MMTCE). To be consistent
with the IPCC Guidelines (IPCC/OECD 1994), this estimate excludes
emissions of 22.6 MMTCE from international transport.
As the table shows, changes in CO2 emissions from fossil fuel
consumption had the greatest impact on U.S. emissions during this
period. While U.S. emissions of CO2 in 1991 were approximately 1.2
percent lower than 1990 emission levels, in 1992 they were about 1.5
percent over 1991 levels, thus returning emissions to about 1990
levels. This trend is largely attributable to changes in total energy
consumption resulting from the economic slowdown in the U.S. economy
and the subsequent recovery. Based on preliminary data for 1993, the
upward trend since 1991 has continued, with 1993 CO2 emissions from
fossil fuel combustion approximately 2.4 percent greater than in
1990.
U.S. CO2 emissions were partly offset by an uptake of carbon in U.S.
forests of 119 MMTCE. This carbon absorption was due to intensified
forest-management practices and the regeneration of forest land
previously cleared for cropland and pasture.
Methane, nitrous oxide, and HFCs and PFCs represent a much smaller
portion of total emissions than CO2. Overall, emissions of these
gases remained relatively constant from 1990 to 1992. Methane
emissions from coal mining declined slightly due to small decreases
in coal production and increases in coalbed methane recovery. Nitrous
oxide emissions remained relatively constant, while HFC emissions
increased slightly, due to increased production of HCFC-22, which
increased by-product emissions of HFC-23.
Figure 3-1 illustrates the relative contributions of the primary
greenhouse gases to total U.S. emissions in 1990. These contributions
were calculated based on the global warming potentials (GWPs) of
these gases, as presented in the figure. Due largely to fossil fuel
consumption, carbon dioxide emissions accounted for the largest
share--85 percent. Methane accounted for 11 percent of total
emissions, which included contributions from landfills and
agricultural activities, among others. The other gases were less
important, with nitrous oxide emissions comprising 2 percent of total
U.S. emissions; HFCs, slightly over 1 percent; and PFCs, about 0.3
percent.
The emissions of the photochemically important gases CO, NOX, and
NMVOCs are not included in Figure 3-1 because there is no agreed-upon
method to estimate their contribution to climate change. These gases
only affect radiative forcing indirectly. However, the U.S.
Environmental Protection Agency prepares publications that provide
data and trends on annual emissions of these gases from 1940 to the
present (e.g., U.S. EPA 1993b). Also, any gases covered under the
Montreal Protocol are not included in this figure because their use
is being phased out, and the IPCC Guidelines (IPCC/OECD 1994)
recommend excluding gases covered by the Montreal Protocol.
The following sections present the anthropogenic sources of
greenhouse gas emissions, briefly discuss the emission pathways,
summarize the emission estimates, and explain the relative importance
of emissions from each source category.
The global carbon cycle is made up of large carbon flows and
reservoirs. Every year, hundreds of billions of tons of carbon in the
form of CO2 are absorbed by the oceans, trees, and other carbon
"sinks" and are emitted to the atmosphere through natural processes.
When in equilibrium, carbon flows among the various reservoirs
roughly balance. Since the Industrial Revolution, however,
atmospheric concentrations of CO2 have risen more than 25 percent,
principally because of fossil fuel combustion (IPCC 1992), which
accounts for 99 percent of total U.S. CO2 emissions. Carbon dioxide
emissions also result directly from industrial processes. And changes
in land use and forestry activities both emit carbon dioxide and have
the potential to act as a sink for CO2 emissions.
Table 3-2 summarizes U.S. emissions and uptake of carbon dioxide,
while the remainder of this section presents detailed information on
the various sources and sinks of CO2 emissions in the United States.
The Energy Sector
Approximately 88 percent of U.S. energy is produced through the
combustion of fossil fuels. The remaining 12 percent comes from
renewable or other energy sources, such as hydropower, biomass, and
nuclear energy (Figure 3-2).
As they burn, fossil fuels emit CO2 due to oxidation of the carbon in
the fuel. The amount of carbon in fossil fuels varies significantly
by fuel type. For example, coal contains the highest amount of carbon
per unit of energy, while petroleum has about 20 percent less carbon
than coal, and natural gas has about 45 percent less.
The U.S. inventory includes carbon dioxide emissions from all fossil
fuel consumption and oil and gas production and storage. Carbon
dioxide emissions from biomass and biomass-based fuel consumption are
reported, but are not included in the national total. This approach
is consistent with the 1994 IPCC Guidelines.
Fossil Fuel Consumption
In 1990 the United States emitted a total of 1,335 MMTCE from fossil
fuel combustion. (Bunker fuels, or fuels used in international
transport, accounted for an additional 22.6 MMTCE.) The
energy-related activities producing these emissions included steam
production for industrial processes, gasoline consumption in
automobiles and other vehicles, heating in residential and commercial
buildings, and the generation of electricity. Petroleum products
across all sectors of the economy were responsible for about 44
percent of total U.S. energy-related CO2 emissions, with coal
accounting for 36 percent, and natural gas, 20 percent.
Industrial Sector. The industrial sector accounts for 34 percent of
U.S. emissions from fossil fuel consumption, making it the largest
end-use source of CO2 emissions (Figure 3-3). About two-thirds of
these emissions result from the burning of fossil fuels to meet
industrial demand for steam and process heat. The remaining one-third
of industrial energy needs is met by electricity for such uses as
motors, electric furnaces and ovens, and lighting.
The industrial sector is also the largest user of nonenergy
applications of fossil fuels, which often store carbon. Fossil fuels
used for producing fertilizers, plastics, asphalt, or lubricants can
store carbon in products for very long periods. Asphalt used in road
construction, for example, stores carbon indefinitely. Similarly, the
fossil fuels used in the manufacture of materials like plastics also
store carbon and release it only if the product is incinerated.
Transportation Sector. The transportation sector is also a major
source of CO2, accounting for about 31 percent of U.S. emissions.
Virtually all of the energy consumed in this sector comes from
petroleum- based products. Nearly two-thirds of the emissions are the
result of gasoline consumption in automobiles and other vehicles,
with other uses-- including diesel fuel for the trucking industry and
jet fuel for aircraft--representing the remainder.
Residential and Commercial Sectors. The residential and commercial
sectors account for about 19 and 16 percent, respectively, of CO2
emissions from fuel consumption. Both sectors rely heavily on
electricity for meeting energy needs, with about two-thirds of their
emissions attributable to electricity consumption. End-use
applications include lighting, heating, cooling, and operating
appliances. The remaining emissions are largely due to the
consumption of natural gas and oil, primarily for meeting heating and
cooking needs.
Electric Utilities. The United States relies on electricity to meet a
significant portion of its energy requirements. In fact, as the
largest consumers of U.S. energy (about 36 percent of total energy),
electric utilities are collectively the largest producers of U.S. CO2
emissions (Figure 3- 3). This sector generates electricity for such
uses as lighting, heating, electric motors, and air conditioning.
Some of this electricity is generated with the lowest CO2-emitting
energy technologies, particularly nonfossil options, such as nuclear
energy, hydropower, and geothermal energy. However, electric
utilities rely on coal for 55 percent of their total energy
requirements and account for about 85 percent of all coal consumed in
the United States.
Fuel Production and Processing
Carbon dioxide is produced via flaring activities at natural gas
systems and oil wells. Typically, the methane that is trapped in a
natural gas system or oil well is flared to relieve the pressure
building in the system or to dispose of small quantities of gas that
are not commercially marketable. As a result, the carbon contained in
the methane becomes oxidized and forms carbon dioxide. In 1990 the
amount of carbon dioxide from the flared gas was approximately 1.8
MMTCE, or about 0.1 percent of total U.S. CO2 emissions.
Biomass and Biomass-Based Fuel Consumption
Biomass fuel is used primarily by the industrial sector in the form
of fuelwood and wood waste. Biomass-based fuel, such as ethanol from
corn or woody crops, is used mainly in the transportation sector.
Ethanol and ethanol blends, such as gasohol, are typically used to
fuel public transport vehicles, such as buses or centrally fueled
fleet vehicles.
Biomass, ethanol, and ethanol-blend fuels do release carbon dioxide.
However, in the long run, the carbon dioxide they emit does not
increase total atmospheric CO2 because the biomass resources are
consumed on a sustainable basis. For example, fuelwood burned one
year but regrown the next only recycles carbon, rather than creating
a net increase in total atmospheric carbon. As a result, CO2
emissions from biomass have been estimated separately from fossil
fuel-based emissions and, as recommended in the 1994 IPCC Guidelines,
are not included in national totals.
For 1990, CO2 emissions from biomass consumption were approximately
48 MMTCE, with the industrial sector accounting for 73 percent, and
the residential sector, 25 percent. Carbon dioxide emissions from
ethanol use in the United States are generally declining, due to a
combination of low gasoline prices and limited ethanol supply. In
1990, total U.S. CO2 emissions from ethanol were estimated to be 1.2
MMTCE, and mostly originated in the South and Midwest, where the
majority of U.S. ethanol is produced and consumed.
Industrial Processes
Emissions are often produced as a by-product of various
nonenergy-related activities. For example, in the industrial sector,
raw materials are chemically transformed from one state to another.
This transformation often releases such greenhouse gases as carbon
dioxide. The production processes that emit CO2 include cement
production, lime production, limestone consumption (e.g., in iron and
steel making), soda ash production and use, and carbon dioxide
manufacture. Total CO2 emissions from these sources were
approximately 15 MMTCE in 1990, accounting for 1 percent of total
U.S. emissions of carbon dioxide.
Cement Production (8.9 MMTCE)
Carbon dioxide is produced primarily during the production of
clinker, an intermediate product from which finished Portland and
masonry cement are made. Specifically, carbon dioxide is created
when calcium carbonate (CaCO3) is heated in a cement kiln to form
lime and carbon dioxide. This lime combines with other materials to
produce clinker, while the carbon dioxide is released into the
atmosphere.
Lime Production (3.2 MMTCE)
Lime is used in steel making, construction, pulp and paper
manufacturing, and water and sewage treatment. It is manufactured by
heating limestone (mostly calcium carbonate--CaCO3) in a kiln,
creating calcium oxide (quicklime) and carbon dioxide, which is
normally emitted to the atmosphere.
Limestone Consumption (1.4 MMTCE)
Limestone is a basic raw material used by a wide variety of
industries, including the construction, agriculture, chemical, and
metallurgical industries. For example, limestone can be used as a
purifier in refining metals, such as iron. In this case, limestone
heated in a blast furnace reacts with impurities in the iron ore and
fuels, generating carbon dioxide as a by-product. It is also used in
flue-gas desulfurization systems to remove sulfur dioxide from the
exhaust gases.
Soda Ash Production and Consumption (1.1 MMTCE)
Commercial soda ash (sodium carbonate) is used in many consumer
products, such as glass, soap and detergents, paper, textiles, and
food. During the manufacture of these products, natural sources of
sodium carbonate are heated and transformed into a crude soda ash, in
which carbon dioxide is generated as a by-product. In addition,
carbon dioxide is released when the soda ash is consumed. Of the two
states that produce natural soda ash, only Wyoming has net emissions
of carbon dioxide, because producers in California recover the CO2
and use it in other stages of production. U.S. emissions of carbon
dioxide from soda ash production were approximately 0.4 MMTCE in
1990, while U.S. soda ash consumption generated about 0.7 MMTCE.
Carbon Dioxide Manufacture (0.3 MMTCE)
Carbon dioxide is used in many segments of the economy, including
food processing, beverage manufacturing, chemical processing, crude
oil products, and a host of industrial and miscellaneous
applications. For the most part, carbon dioxide used in these
applications will eventually be released into the atmosphere.
Changes in Forest Management and Land Use
When humans use and alter the biosphere through changes in land use
and forest-management activities, they alter the natural balance of
trace- gas emissions and uptake. These activities include clearing an
area of forest to create cropland or pasture, restocking a logged
forest, draining a wetland, or allowing a pasture to revert to a
grassland or forest.
Forests, which cover about 295 million hectares (737 million acres)
of U.S. land in the contiguous 48 states (USDA/USFS 1990), are a
potentially important terrestrial sink for carbon dioxide. Because
approximately half the dry weight of wood is carbon, as trees add
mass to their trunks, limbs, and roots, more carbon is stored in the
trees than is released to the atmosphere through respiration and
decay. Soils and vegetative cover also provide a potential sink for
carbon emissions.
In the United States, improved forest-management practices and the
regeneration of previously cleared forest areas have actually
increased the amount of carbon stored on U.S. lands. This uptake of
carbon is an ongoing result of land-use changes in previous decades.
For example, because of improved agricultural productivity and the
widespread use of tractors, the rate of clearing forest land for crop
cultivation and pasture slowed greatly in the late nineteenth
century, and by 1920 this practice had all but ceased. As farming
expanded in the Midwest and West, large areas of previously
cultivated land in the East were brought out of crop production,
primarily between 1920 and 1950, and were allowed to revert to forest
land or were actively reforested. The regeneration of forest land
greatly increases carbon storage in both standing biomass and soils,
and the impacts of these land-use changes are still affecting carbon
fluxes from forests in the eastern United States.
In addition to land-use changes in the early part of this century,
carbon fluxes from forests in the East are affected by a trend toward
managed growth on private land in recent decades, resulting in a near
doubling of the biomass density in eastern forests since the early
1950s. More recently, the 1970s and 1980s saw a resurgence of
federally sponsored tree- planting programs (e.g., the Forestry
Incentive Program) and soil-conservation programs (e.g., the
Conservation Reserve Program), which have focused on reforesting
previously harvested lands, improving timber-management activities,
combating soil erosion, and converting marginal cropland to forests.
As a result of these activities, the net CO2 flux from standing
biomass and vegetative cover in 1990 was estimated to have been an
uptake (sequestration) of 119 MMTCE. The Northeast, North Central,
and South Central regions of the United States accounted for 99
percent of the uptake of carbon, largely due to high growth rates
that are the result of intensified forest-management practices and
the regeneration of forest land previously cleared for cropland and
pasture. Western states are responsible for a small net release of
carbon, reflecting mature forests with a near balance among growth,
mortality, and removals.
However, there are considerable uncertainties associated with the
estimates provided for the net carbon flux from U.S. forests. For
example:
--The impacts of forest management activities on soil carbon are very
uncertain. Since soils contain more than 50 percent of the total
stored forest carbon in the United States, forest-management
activities can have a large impact on flux estimates. However,
because of uncertainties associated with soil carbon flux, this
component is not included in the U.S. estimate at this time.
--The United States has assumed that harvested timber effectively
results in immediate carbon emissions. This assumption is consistent
with the methodology recommended by the IPCC (IPCC/OECD, 1994).
However, other studies that model the product "pools" estimate a net
accumulation of carbon in 1990.
--The current estimate does not include forest land in Alaska and
Hawaii or reserved timber land throughout the United States.
--Forest management activities may also result in fluxes of other
greenhouse and photochemically important gases. Dry soils are an
important sink for CH4, are a source of N2O, and are both a source
and a sink for CO. Vegetation is a source of several NMHCs
(nonmethane hydrocarbons, a subset of NMVOCs). However, the effects
of forestry activities on these gases is highly uncertain, and the
possible fluxes are not included in the U.S. inventory.
Methane Emissions
Atmospheric methane (CH4) is second only to carbon dioxide as an
anthropogenic source of the greenhouse effect. Methane'