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8
Findings and Conclusions
This study reviews current knowledge about greenhouse warming
and examines a wide variety of potential responses. The panel finds
that, even given the considerable uncertainties in our knowledge of
the relevant phenomena, greenhouse warming poses a potential threat
sufficient to merit prompt responses. People in this country could
probably adapt to the likely changes associated with greenhouse
warming. The costs, however, could be substantial. Investment in
mitigation measures acts as insurance protection against the great
uncertainties and the possibility of dramatic surprises. In
addition, the panel believes that substantial mitigation can be
accomplished at modest cost. In other words, insurance is
cheap.
These responses, however, must be based on consideration of the
uncertainties, costs of actions and inaction, and other factors.
The panel believes they should be based on the approach outlined in
Chapter 4. Actions that would help people and natural systems adapt
to climate change are described in Chapter 5. Actions to mitigate
greenhouse warming are described in Chapter 6.
The findings and conclusions presented here draw on the detailed
assessments performed by the other three panels contributing to
this study: the Effects Panel (Part Two), the Mitigation Panel
(Part Three), and the Adaptation Panel (Part Four). The Synthesis
Panel, however, considered additional materials in its
deliberations and in the preparation of this report. These include,
for example, the reports of the three IPCC working groups, the
conference statement from the Second World Climate Conference,
statements from other international meetings, publications of the
national laboratories and other research organizations in the
United States, and documents prepared in other countries. The
findings and conclusions of this
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panel reflect additional analysis, deliberation, and judgment
beyond those of the other panels contributing to this study.
Policy Considerations
The phenomenon of greenhouse warming is complex, and so are the
possible responses to it. First, the extent, timing, and variation
of future warming and its likely impacts need to be assessed.
Second, both the cost and the effectiveness of options to slow
greenhouse warming must be estimated and compared to the costs of
postponing action. Third, the possible advantages and disadvantages
of these actions need to be evaluated in light of the extent to
which people, plants, and animals are likely to adjust by
themselves or with assistance to changes in the climate. Fourth,
the policymaker needs to evaluate these actions in comparison to
other ways resources might be used. Before acting, we need to be
confident that expenditures to slow climate change make sense.
Fifth, decision makers will judge all these factors in a broader
context. Responses to greenhouse warming will be determined by
people worried about economic growth, food supply, energy
availability, national security, and a host of other problems. Many
responses appear to produce sizable benefits with regard to other
goals, such as reducing air pollution. This study makes no attempt
to assess these additional dividends. Instead, it focuses on
response to greenhouse warming as such.
Capacities of Industrialized and
Developing Countries
Different countries have quite different capacities to respond
to change. Poverty, in particular, makes people vulnerable to
change and substantially reduces their flexibility in responding to
change. Countries with low percapita income face difficult
trade-offs between stimulating economic development and alleviating
environmental problems. These countries, which already have
difficulty coping with environmental stresses today, will be even
more sorely pressed when confronted by climate change.
This report examines response to greenhouse warming in the
United States, a country richly endowed with natural and human
resources, and one benefiting from a geography that encompasses
many climate zones. Compared to many other countries, the United
States is well situated to respond to greenhouse warming.
This panel does not attempt to view greenhouse warming from the
perspective of a country less well endowed. Of course, greenhouse
warming is a global phenomenon, and many global aspects must be
included in any analysis. Nevertheless, most of the data utilized
in this study to evaluate
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mitigation and adaptation options relate to the United States. A
more comprehensive examination must wait for future studies.
Taxes and Incentives
Decisions about energy use and other activities that emit
greenhouse gases are made daily, even hourly, by 250 million people
in the United States in many different areas from transportation to
hair drying. Experience here and abroad has shown the inducements
of prices and taxes to be a sure way to transmit government
policies to decentralized decision makers. Achieving significant
reductions in greenhouse gas emissions, however, could involve
considerable sacrifice and economic disruption.
There are advantages of market-incentive approaches, but they
are not universal. For particular technologies, like the
chlorofluorocarbons (CFCs), it may be quicker to use direct
regulatory interventions such as emissions limits or caps, although
buttressing these with taxes can ensure that the regulations are
enforced. An alternative to taxes that has been suggested, and
endorsed by several foreign governments and the United States in
the Clean Air Act, is establishing emission limits. While this
approach seems reasonable on the surface, it has significant
shortcomings in implementation.
The major defect with regulatory actions such as emission limits
is that there is no easy way that the government can directly
control emissions from so many different and separate sources.
However, regulation as a technology-forcing mechanism has
contributed to reducing emissions of key air pollutants in the
United States. It other areas it has been less successful.
Taxes and regulations can discourage or prevent people from
taking actions that would increase greenhouse gas emissions;
incentives of various kinds can encourage them to act in ways that
reduce emissions. If interventions are needed, this panel believes
that, in general, incentive-type measures are preferable.
Fundamental and Applied Research
Research is inexpensive in comparison with many other policy
options that could make a difference in greenhouse warming. The
federal research budget on topics related to global climate change
is a little more than $1 billion for fiscal year 1991, which is
small in comparison to the expected impact or costs of climate
change. Although these funds have been identified as applying to
greenhouse warming research, some of them contribute to other
objectives as well. Policy should be designed and executed in ways
that increase our understanding of the way human activity affects
greenhouse warming.
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Representative terms from entire chapter:
gas emissions
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Research on the actual impacts of climate change may identify
vulnerabilities and highlight areas for policy action. Every year
there are droughts, heat waves, severe storms, and other such
phenomena. Understanding how economies and communities of plants
and animals are affected by extreme climate events, and whether
those responses are changing over time, could provide important
guidance for policy choices.
Better understanding of how biological communities function as
both sources and sinks of greenhouse gases, especially CO2, might also help anticipate the
consequences of greenhouse warming. More detailed knowledge about
phenomena affecting radiative forcing, such as cloud physics and
chemistry, or of key mechanisms in the global climate system, such
as ocean currents and heat transfers, could help identify where
actions might have greatest leverage. Research satellites capable
of measuring the energy balance of the earth are necessary, as is
maintaining thermometer measurement networks.
Most research up to now has emphasized climatological issues.
The global climate change budget in the United States is about 95
percent on the physical phenomena of atmosphere, oceans, and so on
and 5 percent on mitigation, adaptation, and impacts. We need to
know more about the social and economic processes generating
greenhouse gas emissions and about the costs of mitigating these
emissions, especially in the energy sector. We need reviews and
assessments of policy options to slow climate change, and
improvements in the data base for understanding economic and
environmental trends relating to global change. Because greenhouse
warming is a global problem encompassing a wide range of areas, it
will be important to establish programs that are interdisciplinary
and examine developing countries as well as high-income countries
like the United States.
A Proposed Framework for Responding to
the Threat of Greenhouse Warming
The analyses performed for this study show that the United
States should be able to adapt to the changes in climate expected
to accompany greenhouse warming. They have also identified a number
of options that could slow or offset the buildup of greenhouse
gases. Other options could help position us to ease future
adaptations to the consequences of greenhouse warming. The fact
that people can adapt, or even that they are likely to do so, does
not mean that the best policy is to wait for greenhouse warming to
occur and let them adapt. Waiting and adapting may sacrifice
overall economic improvement in the long run.
The panel has sorted response policies into five categories: (1)
reducing or offsetting greenhouse gas emissions, (2) enhancing
adaptation to greenhouse warming, (3) improving knowledge for
future decisions, (4) evaluating
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geoengineering options, and (5) exercising international
leadership. The recommended options in each category are described
in Chapter 9.
General Conclusions
In conducting this study, the panel first established the
approach and framework described in Chapter 4. The information and
data summarized in Chapters 5 and 6 were then gathered and
analyzed. On this basis, the Synthesis Panel reached the collective
judgment that the United States should undertake not only several
actions that satisfy multiple goals but also several whose costs
are justified mainly by countering or adapting to greenhouse
warming. The panel believes that a systematic implementation of the
complete set of low-cost options described in Chapter 9 is
appropriate. The panel concludes that options requiring great
expenses are not justified at this time.