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9
Recommendations
Despite the great uncertainties, greenhouse warming is a potential threat
sufficient to justify action now. Some current actions could reduce the
speed and magnitude of greenhouse warming; others could prepare people
and natural systems of plants and animals for future adjustments to the
conditions likely to accompany greenhouse warming.
There are a number of mitigation and adaptation options available to the
United States. This panel recommends implementation of the options pre-
sented below through a concerted program to start mitigating further buildup
of greenhouse gases and to initiate adaptation measures that are judicious
and practical. It also recommends a strong scientific program to continue to
reduce the many uncertainties. International cooperation is essential in all
areas.
The recommendations are generally based on low-cost, currently avail-
able technologies. Topics for which new information or techniques must be
developed are clearly identified. In many instances, more detailed treatments
can be found in the separate reports of the Effects Panel, the Mitigation
Panel, or the Adaptation Panel. The numbers in parentheses refer to pages
in this report where these topics are discussed.
REDUCING OR OFFSETTING EMISSIONS OF
GREENHOUSE GASES
Three areas dominate the analysis of reducing or offsetting current emis-
sions: (1) eliminating halocarbon emissions, (2) changing energy policy,
and (3) utilizing forest offsets. Eliminating CFC emissions is the biggest
single contribution in the short run. Energy policy recommendations in-
clude reducing emissions related to both consumption and production. Rec
72
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RECOMMENDATIONS
73
ommendations on both global and domestic programs are included under
forest offsets. The United States could reduce or offset its greenhouse gas
emissions by between 10 and 40 percent of 1990 levels at low cost, or at
some net savings, if proper policies are implemented.
Halocarbon Emissions
Continue the aggressive phaseout of CFC and other halocarbon emissions
and the development of substitutes that minimize or eliminate green-
house gas emissions. (pp. 52, 54-58)
Chlorofluorocarbons not only have a role in the depletion of stratospheric
ozone, they also contribute a significant portion of the radiative forcing
(i.e., the ability to "trap" heat in the atmosphere) attributable to human
activities. The 1987 Montreal Protocol to the Vienna Convention set goals
regarding international phaseout of CFC manufacture and emissions. The
United States is a party to that agreement as well as to the London Protocol,
which requires total phaseout of CFCs, haloes, and carbon tetrachloride by
2000 in industrialized countries and by 2010 in developing countries. Un-
less this agreement is forcefully implemented, the use of CFCs may con-
tinue to intensify greenhouse warming. Every effort should be made to
develop economical substitutes that do not contribute to greenhouse warm-
ing.
Energy Policy
Study in detail the "full social cost pricing" of energy, with a goal of
gradually introducing such a system. (pp. 30-31, 67, 68)
On the basis of the principle that the polluter should pay, pricing of
energy production and use should reflect the full costs of the associated
environmental problems. The concept of full social cost pricing is a goal
toward which to strive. Including all social, environmental, and other costs
in energy prices would provide consumers and producers with the appropriate
information to decide about fuel mix, new investments, and research and
development. Such a policy would not be easy to design or implement.
Unanticipated winners and losers could emerge, either through improper
accounting of externalities, lack of knowledge, or lack of incorporation of
other concerns (such as energy security) or through cleverness and innova-
tion. Phasing such a policy in over time is essential to avoid shocks caused
by rapid price changes. It would best be coordinated internationally.
Reduce the emission of greenhouse gases during energy use and con-
sumption by enhancing conservation and efficiency (pp. 54-58, 59), in-
cluding action to:
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-
74
POLICY IMPLICATIONS OF GREENHOUSE WARMING
.
Adopt nationwide energy-efficient building codes
· Improve the efficiency of the U.S. automotive fleet through the use of
an appropriate combination of regulation and tax incentives
· Strengthen federal and state support of mass transit
· Improve appliance efficiency standards
· Encourage public education and information programs for conserva-
tion and recycling
· Reform state public utility regulation to encourage electrical utilities
to promote efficiency and conservation
.
Sharply increase the emphasis on efficiency and conservation in the
federal energy research and development budget
· Utilize federal and state purchases of goods and services to demonstrate
best-practice technologies and energy conservation programs
The efficiency of practically every end use of energy can be improved
relatively inexpensively. Major reductions could be achieved in energy use
in existing buildings through improvements in lighting, water heating, re-
frigeration, space heating and cooling, and cooking. Gains could be achieved
in transportation by improving vehicle efficiency without downsizing or
altering convenience. Significant gains could also be achieved in industrial
electricity use through fuel switching and improvements in process technologies.
Initial calculations show that some options could be implemented at a net
savings. There are informational barriers to overcome, however. For example,
homeowners may not be aware of the gains to be realized from high-efficiency
furnaces. There are also institutional barriers. For example, most public
utility commissions disallow a rate of return to power companies on efficiency
and conservation options. The panel concludes that energy efficiency and
conservation is a rich field for reducing greenhouse gas emissions.
Make greenhouse warming a key factor in planning for our future
energy supply mix. The United States should adopt a systems approach
that considers the interactions among supply, conversion, end use, and
external effects in improving the economics and performance of the
overall energy system. (pp. 54-58, 59) Action items include efforts to:
· Develop combined cycle systems that have efficiencies approaching
60 percent for both coal- and natural-gas-fired plants
· Encourage broader use of natural gas by identifying and removing
obstacles in the distribution system
· Develop and test operationally a new generation of nuclear reactor
technology that is designed to deal with safety, waste management, and
public acceptability
· Increase research and development on alternative energy supply tech-
nologies (e.g., solar), and design energy systems utilizing them in conjunc-
tion with other energy supply technologies to optimize economy and performance
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RECOMMENDATIONS
75
· Accelerate efforts to assess the economic and technical feasibility of
CO2 sequestration from fossil-fuel-based generating plants
The future energy supply mix will change as new energy technologies
and greenhouse warming take on increased importance. A "systems approach"
should be used to optimize the economics and performance of future energy
systems. Interactions among supply options, conversion systems, end use,
and external effects should receive much more attention than they have in
the past. Actions for improving energy supply systems must cover all
important elements in the mix. Also, it is important to prepare for the
possibility that greenhouse warming may become far more serious in the
future.
Alternative energy technologies are unable currently or in the near future
to replace fossil fuels as the major electricity source for this country. If
fossil fuels had to be replaced now as the primary source of electricity,
nuclear power appears to be the most technically feasible alternative. But
nuclear reactor designs capable of meeting fail-safe criteria and satisfying
public concerns have not been demonstrated. A new generation of reactor
design is needed that adequately addresses the full range of safety, waste
management, economic, and other issues confronting nuclear power. Focused
research and development work on a variety of alternative energy supply
sources could change the priorities for energy supply within the 50-year
time span addressed in this study.
Forest Offsets
Reduce global deforestation (pp. 64-65J, including action to:
· Participate in international programs to assess the extent of deforesta-
tion, especially in tropical regions, and to develop effective action plans to
slow or halt deforestation
· Undertake country-by-country programs of technical assistance or other
. .
Incentives
· Review U.S. policies to remove subsidies and other incentives con-
tributing to deforestation in the United States
In addition to reducing the uptake of CO2 in plants and soils and being a
source of atmospheric CO2, deforestation contributes to other important
problems: loss of species and reduction in the diversity of biologic systems,
soil erosion, decreased capacity to retain water in soil and altered runoff of
rainfall, and alteration of local weather patterns. The United States now has
increasing forest cover, but tropical forests worldwide are being lost at a
rapid rate. Nearly every aspect of tropical deforestation, however, is diffi-
cult to measure. Even the amount of land deforested each year is subject to
disagreement. Nevertheless, action should be initiated now to slow and
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POLICY IMPLICATIONS OF GREENHOUSE WARMING
eventually halt tropical deforestation. Such programs need to be developed
by those countries where the affected forests are located in cooperation with
other countries and international organizations. Developing countries with
extensive tropical forests will require substantial technological and devel-
opmental aid if this goal is to be reached.
Explore a moderate domestic reforestation program and support in-
ternational reforestation efforts. (pp. 54-58, 65-66)
Reforestation offers the potential of offsetting a large amount of CO2
emissions, but at a cost that increases sharply as the amount of offset in-
creases. These costs include not only those of implementation, but also the
loss of other productive uses of the land planted to forests, such as land for
food production. Reforesting can, at best, only remove CO2 from the at-
mosphere and store it during the lifetime of the trees. When a forest matures,
the net uptake of CO2 stops. If the reforested areas are then harvested, the
only true offset of CO2 buildup is the amount of carbon stored as lumber or
other long-lived products. However, the wood might be used as a
sustained-yield energy crop to replace fossil fuel use. The acreage available
within the United States for reforestation, and the amount of CO2 that could
be captured on these lands with appropriate kinds of trees, are controversial
and may be limited. Many details remain to be resolved.
ENHANCING ADAPTATION TO GREENHOUSE WARMING
The nature and magnitude of the weather conditions and events that
might accompany greenhouse warming at any particular location in the fu-
ture are extremely uncertain. This panel examined the sensitivity of the
affected human and natural systems to the events and conditions likely to
accompany greenhouse warming. The panel's adaptation recommendations
are intended to help make the affected systems less vulnerable to future
climate change. Most of the recommendations, by making the systems
more robust, also help them deal with current climate variability. Some,
such as purchasing land or easements for specific habitats or corridors for
migration, would not be needed if greenhouse warming does not occur.
Specific adaptation recommendations address agriculture, water systems,
long-lived structures, and preservation of biodiversity.
Maintain basic, applied, and experimental agricultural research to
help farmers and commerce adapt to climate change and thus ensure
ample food. (pp. 36-37)
Farming is the preeminent activity essential to humanity that is exposed
to climate. During recent decades, its successful adaptation to diverse cli-
mates and changing demand rested on vigorous research and application by
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RECOMMENDATIONS
77
both government and business. As climate changes, adapted varieties, spe-
cies, and husbandry must be more promptly sought and then proven in the
reality of fields and commerce. Special challenges are (1) while adapting,
to sustain the natural resources of land, water, and genetic diversity that
underlie farming; (2) to be productive during extreme weather conditions;
(3) to manage irrigation to produce more food with less water; and (4) to
exploit the opportunity of increased fertilization provided by more CO2 in the
air.
Make water supply more robust by coping with present variability
by increasing efficiency of use through water markets and by better
management of present systems of supply. (pp. 38-39)
Currently, weather and precipitation cause natural variability in the water
supply, in soil, and in streams, and changes in climate could be expected to
produce even greater variability. Fortunately, coping with the present vari-
ability makes supply more reliable or robust for future climate change when
needed. In many places, supply and demand can be better matched by
raising the efficiency of use through changes in rights, markets, and prices,
by clever management and engineering of irrigation, and by changes in
urban styles of living (e.g., water-efficient landscaping and reduced lawn
maintenance). Because the joint management of supplies under the juris-
diction of several agencies can increase water yields substantially, the pro-
tracted negotiations for such cooperation should begin now.
Plan margins of safety for long-lived structures to take into consider-
ation possible climate change. (pp. 41-42)
Margins of safety adequate for past climate may be insufficient for a
changed climate. Most investments like bridges, levees, or dams have lives
as long as the time expected for climate to change. The margins used in
constructing such structures are generally computed from the historical fre-
quency of extremes like storms or droughts. The possibility of greenhouse
warming must now be considered in computing these margins of safety. A
logical procedure for justifying investment in a wider margin of safety now
involves two considerations: its cost in terms of its expected present value
compared to that of retrofitting the structure when needed, and the probabil-
ity that the alteration will in fact be needed.
Move to slow present losses in biodiversity (pp. 37-38, 44), including
. .
taking action to:
· Establish and manage areas encompassing full ranges of habitats
· Inventory little-known organisms and sites
· Collect key organisms in repositories such as seed banks
· Search for new active compounds in wild plants and animals
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POLICY IMPLICATIONS OF GREENHOUSE WARMING
Control and manage wild species to avoid over-exploitation
Pursue captive breeding and propagation of valuable species that have
had their habitats usurped or populations drastically reduced
~ . . .
.
Review pollcles' lawn and administrative procedures that have the
effect of promoting species destruction
· Consider purchasing land or easements suitable for helping vulnerahle
species to migrate to new habitats
, Al Or ^~O , ~, _. ~,~
Even without greenhouse warming, a series of steps to slow present
losses in biodiversity are warranted. Any future climate change is likely to
increase the rate of loss of biodiversity while it increases the value of
genetic resources. Greenhouse warming therefore adds urgency to pro-
grams to preserve our biological heritage. Much remains to be done to
ensure that key habitats are protected, that major crop cultivars are col-
lected, and that extensive options are retained for future use. Serious initiatives
have only recently been started. In most countries, the driving forces be-
hind the degradation of biodiversity relate to the development context within
which people farm; harvest forest products; utilize fresh water, wildlife, and
fish; and otherwise invest in land or water. Moreover, there are policies
that actually promote destruction by fostering open tillage crops, short-term
timber-harvesting concessions, excessive use of water, and inappropriate
fishing technology. If climate changes, existing reserves and parks may
become unsuitable for species currently living there, and landscape frag-
mentation may make migration more difficult. Conservation efforts should
give more attention to corridors for movement, to assisting species to surmount
barriers, and to maintaining species when their natural habitats are threatened.
.
IMPROVING KNOWLEDGE FOR FUTURE DECISIONS
Data collection and applied research can make exceptional contributions
in reducing uncertainties of greenhouse warming. The return on investment
in research is likely to be great. The panel identifies the following areas for
emphasis: collection and interpretation of data on climate change. im~rove
. , ~. . . . .
"7- 7 ----r
menl in weather forecasting, key physical mechanisms in climate change,
and research on the interactions between the biosphere, human activities,
and the climate system.
Continue and expand the collection and dissemination of data that
provide an uninterrupted record of the evolving climate and of data
that are (or will become) needed for the improvement and testing of
climate models. (pp. 17-19, 20-23, 24-25)
Current data collection programs should be maintained and should be
continued after the new (and different) collection systems (e.g., EOS, the
Earth Observing System) have become operational. Earlier modes of col
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RECOMMENDATIONS
79
lection should be phased out only when the interpretation of new and old
data streams has proceeded for an appropriate time. Uncertainties in the
climate record and its interpretation should not be exacerbated by change in
instrumentation.
Continuous monitoring of key indices that can reveal climate change is
needed for identifying adaptations that will be needed in the future. These
include the supply of water in the streams and soil of a region, sea level,
ocean currents, and dates of seasonal events like blooms and migrations.
Improve weather forecasts, especially of extremes, for weeks and seasons
to ease adaptation to climate change. (p. 34)
If storms could be accurately forecast several days in advance, people
could prepare for or escape them and hence could live in climates with
greater variation and extremes. If extremely cold or dry seasons could be
foreseen confidently, appropriate crops could be planted and harvested, and
floods and droughts managed more effectively. Continued improvement of
several-day forecasts, provision and dissemination of forecasts for addi-
tional parts of the world, and increasing knowledge of atmosphere-ocean
interactions may help enhance adaptation to greenhouse warming.
Continue to identify those mechanisms that play a significant role in
the climatic response to changing concentrations of greenhouse gases.
Develop and/or improve quantification of all such mechanisms at a scale
appropriate for climate models. (pp. 17-19, 25-26)
Some of the mechanisms already known to need such attention include
those involving the role of clouds, the role of the oceans in heat transfer,
the possible release of CO2 in the oceans (i.e., into the atmosphere) with
change in ocean temperature, the role of the biosphere in the storage and
release of CO2 and CH4, and the effect of particle concentrations on cloud
cover and radiative balance.
It is also necessary to improve the quantification (at a scale suitable for
climate models) of processes such as precipitation, soil moisture, and run-
off. Some current mathematical characterizations are unable to provide
credible regional projections of these factors even when used for scenarios
in which the greenhouse gas concentrations are not changing.
Conduct field research on entire systems of species over many years
to learn how CO2 enrichment alters the mix of species and changes the
total production or quality of biomass. Research should be accelerated
to determine how greenhouse warming might affect biodiversity. (pp. 37-
38, 70)
Communities of plants and animals are complex and intricate. Simpli-
fied and controlled experiments in laboratories can help understand them
better. Greenhouse warming is likely to increase the rate of loss of biodiversity,
and so it adds urgency to experimental programs to preserve our biological
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POLICY IMPLICATIONS OF GREENHOUSE WARMING
heritage. But scientists also must learn how disparate, entire systems of
species live and react to changes in their habitats and especially to changes
in the concentration of CO2. The effect of combined CO2 enrichment and
greenhouse warming on the mix of species and other attributes of natural
communities cannot be determined without field research conducted over
many years.
Strengthen research on social and economic aspects of global change
and greenhouse warming. (pp. 69-70)
The U.S. research program has emphasized issues of atmospheric chem-
istry, climate modeling, and monitoring, while relatively little attention has
been given to issues of impacts, mitigation, and adaptation. Major priori-
ties should be (1) improved understanding of the costs for mitigating green-
house gas emissions, particularly in the energy sector, (2) more detailed
studies of the impacts of and adaptations to climate change, (3) a better
understanding of the social and economic processes generating greenhouse
~ A ~
gas emissions, At) policy analysts of options and strategies relating to climate
change, and (5) improvements in the data hase for ,~ncl~.r~nn~lina Omit
and environmental trends relating to global chance.
~, (_} - - O -
Greenhouse warming is a global problem; therefore it will be important
to encourage interdisciplinary and international programs. Thorough ana-
lytical studies of the impacts of greenhouse warming currently are limited
to a few relatively high income countries. Yet it is the poor countries, with
a large fraction of their population and output in the farm sector, who are
the most vulnerable to climate change. In the research areas listed above, it
will be important to examine behavior in developing countries as well as in
high-income countries like the United States.
EVALUATING GEOENGINEERING OPTIONS
Undertake research and development projects to improve our under-
standing of both the potential of geoengineering options to offset global
warming and their possible side-effects. This is not a recommendation
that geoengineering options be undertaken at this time, but rather that
we learn more about their likely advantages and disadvantages. (pp. 53-
59, 60)
Several geoengineering options appear to have considerable potential for
offsetting global warming and are much less expensive than other options
being considered. Because these options have the potential to affect the
radiative forcing of the planet, because some of them cause or alter a variety
of chemical reactions in the atmosphere, and because the climate system is
poorly understood, such options must be considered extremely carefully.
These options might be needed if greenhouse warming occurs, climate sen
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RECOMMENDATIONS
81
sitivity is at the high end of the range considered in this report, and other
efforts to restrain greenhouse gas emissions fail.
The first set of geoengineering options screens incoming solar radiation
with dust or soot in orbit about the earth or in the atmosphere. The second
set changes cloud abundance by increasing cloud condensation nuclei through
carefully controlled emissions of particulate matter. Despite their theoreti-
cal potential, there is convincing evidence that the stratospheric particle
options contribute to depletion of the ozone layer. The stratospheric particle
options should be pursued only under extreme conditions or if additional
research and development removes the concern about these problems. The
cloud stimulation option should be examined further and could be pursued
if concerns about acid rain could be managed through the choice of materials
for cloud condensation nuclei or by careful management of the system. The
third class increases ocean absorption of CO2 through stimulating growth of
biological organisms. The panel recommends that research projects be un-
dertaken to improve understanding of both the potential of these options
to offset global warming and their possible side-effects. Such assessments
should involve international cooperation. This is not a recommendation for
implementing these options at this time.
EXERCISING INTERNATIONAL LEADERSHIP
As the largest source of current greenhouse gas emissions, the United
States should exercise leadership in addressing responses to greenhouse
warming.
Control of population growth has the potential to make a major con-
tribution to raising living standards and to easing environmental prob-
lems like greenhouse warming. The United States should resume full
participation in international programs to slow population growth and
should contribute its share to their financial and other support. (p. 64)
Population size and economic activity both affect greenhouse gas emis-
sions. Even with rapid technological advances, slowing global population
growth is a necessary component of a long-term effort to control worldwide
emissions of greenhouse gases. Reducing population growth alone, however,
may not reduce emissions of greenhouse gases because it may also stimulate
growth in per capita income. If the nature of economic activity (especially
energy use) changes, some growth will be possible with far less greenhouse
. .
gas emissions.
Encouraging voluntary population control programs is of considerable
benefit for slowing future emissions of greenhouse gases. In addition, countries
vulnerable to the possible impacts of climate change would be better able to
adapt to those changes if their populations were smaller and they had higher
per-capita income.
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POLICY IMPLICATIONS OF GREENHOUSE WARMING
The United States should participate fully with officials at an appro-
priate level in international agreements and in programs to address
greenhouse warming, including diplomatic conventions and research
and development efforts. (p. 66)
There is a growing momentum in the international community for completion
of an international agreement on climate change in time for signing at the
1992 United Nations World Conference on Environment and Development.
The United States should participate fully in this activity and continue its
active scientific role in related topics. The global character of greenhouse
warming provides a special opportunity in the area of research and develop-
ment. International cooperation in research and development should be
encouraged through governmental and private sector agreements. Interna-
tional organizations providing funds for development should be encouraged
to evaluate projects meeting demand for energy growth by conservation
methods on an equal footing with projects entailing construction of new
production capacity.
Representative terms from entire chapter:
greenhouse gas
