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We believe that these policies will be more easily implemented and accepted when they are also designed to simultaneously address other environmental issues such as air pollution and soil ero

sion.

They go all the way from voluntary programs and negotiated agreements with industry; utility demand-side programs; tradeable emissions permits to make it most cost-effective; and many others. One crucial issue, though, is also stimulating research, development and demonstration of new technologies.

In conclusion, policymakers are faced with responding to the risks posed by the anthropogenic emissions of greenhouse gases in the face of significant scientific uncertainties. However, these uncertainties must be considered in the context that climate-induced environmental changes cannot be reversed quickly, if at all, due to the long time scales, decades to millennia associated with the climate system.

We also noted that decisions taken during the next few years may limit the range of possible policy options in the future because high near-term emissions-that is to say, today and the next few decades-would require deep reductions in the future to meet any given target concentration.

Therefore, we deduce that delay in action might reduce the overall cost of mitigation because of potential technological advances, but it could also increase both the rate and eventual magnitude of climate change, and hence the adaptation and damage costs.

Therefore, uncertainty does not mean a nation or the world community cannot position itself better to cope with the broad range of possible climate changes, or to protect itself against potentially costly future outcomes.

Delay in such measures may actually leave the Nation or the world poorly prepared to deal with the adverse changes and may increase the possibility of irreversible or very costly damages. While human-induced climate changes

Mr. ROHRABACHER. Dr. Watson-
Dr. WATSON. [continuing]

issue

-

- -are a serious environmental

Mr. ROHRABACHER. Dr. Watson-
Dr. WATSON. One more sentence?
Mr. ROHRABACHER. All right.

Dr. WATSON. Fine. I'll give you two sentences.

-a coordinated attack on the climate change issue by the science. community, industry, business, environmental organizations, and governments all working towards a common goal of the cost-effective protection of human health and vital ecological systems is within our grasp.

Thank you.

Statement of

Dr. Robert T. Watson
Co-Chair Working Group II
Intergovernmental Panel on Climate Change
and

Associate Director of Environment
Office of Science and Technology Policy
Executive Office of the President
before the

Subcommittee on Energy and the Environment
Committee on Science

United States House of Representatives
November 16, 1995

Mr. Chairman and Members of the Sub-committee:

I greatly appreciate being given the opportunity to present the latest scientific findings of the international scientific community to you and your subcommittee. Today I am testifying in my capacity as the co-chair of Working Group II of the Intergovernmental Panel on Climate Change (IPCC). Working Group II of the IPCC reviewed the state of knowledge concerning the impacts of climate change on human health, ecological systems, and socio-economic sectors, including agriculture, forestry, fisheries, water resources, and human settlements. The Panel also assessed the technical and economic feasibility of a range of adaptation and mitigation strategies. The mitigation strategies assessed included approaches to reduce emissions and enhance sinks of greenhouse gases from a wide range of sectors including energy supply and demand, industry, transportation, and agriculture and forestry.

This assessment is one of a series of international scientific assessments conducted by the Intergovernmental Panel on Climate Change (IPCC) under the auspices of the World Meteorological Organization and the United Nations Environment Programme. The first assessment report was released in 1990, with special issues on selected topics in 1992 and 1994. Annex I briefly describes the IPCC reports, process and structure.

My testimony represents the views of the large majority of the international scientific community from academia, government laboratories, environmental organizations and industry. Hundreds of scientists, from more than 50 developed and developing countries, have been involved in the preparation of this assessment. This assessment, which was formally accepted by governments at a meeting in Montreal, Canada in October, was extensively peer-reviewed by scientific experts and by governments. The Summary for Policymakers (SPM) was written by the chapter chairs, peerreviewed by scientific experts and governments, and then approved verbatim by government representatives. The process which was used to prepare and review the IPCC Working Group II assessment, and its SPM, is described in Annex II. The SPM is included verbatim in my testimony in Annex III.

Part I:

Human Activities are Implicated in Changes in the Earth's Climate Before summarizing the key findings from Working Group II let me first summarize the present state of understanding of the climate system.

The Earth's climate has been relatively stable during the past 10,000 years, the time during which modern society has evolved, and largely adapted to the prevailing local climate and its natural variability. However, the Earth's climate is now changing. The Earth's surface temperature this century is warmer than any other century during the last thousand years; the Earth's surface

temperature has increased by about half a degree centigrade over the last century; the last few decades have been the hottest this century; and this year may be the hottest on record.

The atmospheric concentrations of greenhouse gases have increased since the beginning of the preindustrial era due to human activities; carbon dioxide by about 30%, methane by more than a factor of two, and nitrous oxide by about 15%. Their concentrations are higher now than at any time during the last 160,000 years, the period for which there is reliable ice-core data, and probably significantly longer. In addition, the atmospheric concentrations of sulfate aerosols have also increased this century. Greenhouse gases tend to warm the atmosphere and, in some regions, aerosols tend to cool the atmosphere.

Theoretical models that take into account the observed increases in the atmospheric concentrations of greenhouse gases and sulfate aerosols simulate quite well the observed changes in both surface temperature and vertical temperature distribution. This suggests that human activities are implicated in the observed changes in the Earth's climate.

Based on the estimated range of climate sensitivities and plausible ranges of greenhouse gas and sulfur dioxide emissions (IPCC IS 92), climate models project that the global mean surface temperature could increase by 1 to 3.5°C by 2100. These projected global-average temperature changes would be greater than recent natural fluctuations, would also occur at a rate significantly faster than observed changes over the last 10,000 years, and would result in temperatures higher than those during the medieval warm period and the Holocene period of 6000 years ago. Associated with these estimated changes in temperature, sea level is projected to increase by 15 95 cm by 2100, caused primarily by thermal expansion of the oceans and the melting of glaciers.

Model calculations show that evaporation will be enhanced as the climate warms, and that there will be an increase in global mean precipitation and an increase in the frequency of intense rainfall. However, not all land regions will experience an increase in precipitation, and even those land regions with increased precipitation may experience decreases in soil moisture, because of enhanced evaporation. Seasonal shifts in precipitation are also projected. In general, precipitation is projected to increase at middle to high latitudes in winter, and soil moisture is projected to decrease in some mid-latitude continental regions during summer.

The incidence of extreme temperature events, floods, droughts, fires and pest outbreaks is expected to increase in some regions, but it is unclear whether there will be changes in the frequency and intensity of extreme weather events such as tropical storms, cyclones, and tornadoes.

While the reliability of regional scale predictions is still low, this does not preclude an assessment of the sensitivity of human health, ecological systems and socio-economic sectors to changes in climate. IPCC Working Group II primarily focused on evaluating the sensitivity and vulnerability of these systems to climate variability and changes in climate, e.g., it assessed how agricultural productivity would change as a result of an increase in temperature or a change in rainfall. This approach isolates the uncertainty in impacts analysis from uncertainties in regional projections of future climate. The lead authors reviewed and synthesized conclusions in the literature regarding thresholds and sensitivities of their systems to changes in climate variables. The response of a system to observed variability or an assumed change is determined through examination of laboratory and in situ studies. The assessment also examined the sensitivity of systems with respect to changes in climatic extremes, the effects of multiple environmental and anthropogenic stresses, the effects of different rates of change, and effects of other factors that would affect adaptation strategies.

Part II:

Human Health, Ecological systems, and Socio-economic Sectors are all Vulnerable to Climate Change

IPCC Working Group II concluded that human-induced climate change is an important new stress, particularly on ecological and socio-economic systems that are already affected by pollution, increasing resource demands, and non-sustainable management practices. They noted that most systems are sensitive to both the magnitude and rate of climate change, but many of the impacts are difficult to quantify because existing studies are limited in scope. They also noted that successful adaptation depends upon technological advances, institutional arrangements, availability of financing and information exchange, and that vulnerability increases as adaptation capacity decreases.

Let me now briefly discuss the implications of climate change for a representative number of systems, i.e., human health, food security, natural ecosystems, and human habitats.

Human Health

Climate change is likely to have wide-ranging and mostly adverse impacts on human health, with significant loss of life. These impacts would arise by both direct and indirect pathways. Direct health effects include increases in (predominantly cardiorespiratory) mortality and illness due to an anticipated increase in the intensity and duration of heat waves. Indirect effects of climate change include increases in the potential transmission of vector-borne infectious diseases (e.g., malaria, dengue, yellow fever, and some viral encephalitis) resulting from extensions of the geographical range and season for vector organisms. This could lead to potential increases in malaria incidence of the order of 50-80 million additional annual cases, primarily in tropical, subtropical, and less well-protected temperate-zone populations. Some increases in non-vector-borne infectious diseases such as salmonellosis, cholera, and giardiasis—also could occur as a result of elevated temperatures and increased flooding.

Food Security

Existing studies show that on the whole, global agricultural production could be maintained relative to baseline production in the face of climate change under doubled equivalent CO2 equilibrium conditions. However, crop yields and changes in productivity due to climate change will vary considerably across regions and among localities, thus changing the patterns of production. Productivity is projected to increase in some areas and decrease in others, especially the tropics and subtropics. Therefore, there may be increased risk of hunger and famine in some locations in the tropics and subtropics where many of the world's poorest people live.

Natural Ecosystems

The composition and geographic distribution of many ecosystems will shift as individual species respond to changes in climate, and there will likely be reductions in biological diversity, and in the goods and services ecosystems provide society, e.g., sources of food, fibre, medicines, recreation and tourism, and ecological services such as controlling nutrient cycling, waste quality, water runoff, and soil erosion. Models project that as a consequence of possible changes in temperature and water availability under doubled equivalent-carbon dioxide equilibrium conditions, a substantial fraction (a global average of one-third, varying by region from one-seventh to two-thirds) of the existing forested area of the world will undergo major changes in broad vegetation types. Climate change is expected to occur at a rapid rate relative to the speed at which forest species grow, reproduce and re-establish themselves. Therefore, species composition of impacted forests is likely to change, and entire forest types may disappear while new assemblages of species and hence new forest ecosystems may be established. Coral reefs are the most biologically diverse marine ecosystems. Sustained increases in water temperatures of 3-4 oC above seasonal high average temperatures can cause significant coral mortality; short-term increases on the order of only 1-2 °C can cause "bleaching", leading to reef destruction.

Human Habitat

Sea-level rise will increase the vulnerability of coastal populations to flooding. Model estimates put about 46 million people per year currently at risk of flooding due to storm surges; a 50 cm sea-level rise would increase this number to about 92 million; a 1 meter sea-level rise would increase this number to 118 million. The estimates will be substantially higher if one incorporates population growth projections. A number of studies have shown that small islands and delta areas are particularly vulnerable to a one-meter sea-level rise. Land losses ranged from 0.05% in Uruguay, 1.0% for Egypt, 6% for Netherlands, 17.5% for Bangladesh, to about 80% of the Marshall Islands, displacing tens of millions of people.

PART III:

Technical Options Exist to Reduce Emissions and Enhance Sinks of
Greenhouse Gases

Significant reductions in greenhouse gas emissions are technically possible and can be economically feasible. These reductions can be achieved by utilizing an extensive array of technologies and policy measures that accelerate technology development, diffusion, and transfer in all sectors, including the energy, industry, transportation, residential/commercial, and agricultural/forestry sectors.

Energy Demand

Numerous studies have indicated that it is possible to reduce energy demand: that 10-30% energy efficiency gains above present levels are feasible at little or no net cost in many parts of the world through technical conservation measures and improved management practices over the next 2 to 3 decades. Using technologies that presently yield the highest output of energy services for a given input of energy, efficiency gains of 50-60% would be technically feasible in many countries over the same time period. Achieving these potentials will depend on future cost reductions, financing and technology transfer, as well as measures to overcome a variety of non-technical barriers.

Energy Supply

It is technically possible to realize deep emissions reductions in the energy supply sector in step with the normal timing of investments to replace infrastructure and equipment as it wears out or becomes obsolete. Promising approaches, not ordered according to priority, include: more-efficient conversion of fossil fuels; switching to low-carbon fossil fuels and suppressing emissions; decarbonization of flue gases and fuels and carbon dioxide storage; switching to non-fossil fuel sources of energy such as nuclear energy or renewable fuels. Technological advances offer new opportunities and declining costs for energy from these sources.

Agriculture and Forestry

Beyond the use of biomass fuels to displace fossil fuels, the management of forests, agricultural lands, and rangelands can play an important role in reducing current emissions of carbon dioxide, methane, and nitrous oxide and enhancing carbon sinks. A number of measures could conserve and sequester substantial amounts of carbon (approximately an additional 60-90 GtC in the forestry sector alone) over the next 50 years. In the forestry sector, costs for conserving and sequestering carbon in biomass and soil are estimated to range widely but can be competitive with other mitigation options.

Policy Instruments

Policies are available to governments that facilitate the penetration of less greenhouse gas-intensive technologies and modified consumption patterns. Many countries have extensive experience with a variety of policies that can accelerate the adoption of such technologies. This experience comes from efforts over the past 20 to 30 years to achieve improved energy efficiency, reduce the environmental impacts of agricultural policies, and meet conservation and environmental goals unrelated to climate change. Policies to reduce net greenhouse gas emissions appear more easily

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