Climate change is likely to extend the geographic ranges and increase the rates of transmission of disease-carrying vectors such as mosquitoes, which can increase the populations exposed to diseases such as malaria, dengue and yellow fever. Globally, the population exposed to malaria could increase by one-third. There could be 50-80 million additional malaria cases per year, assuming no change in public health protection. Climate change can reduce air quality and increase levels of air borne pollen and spores, which exacerbate respiratory disease, asthma, and allergic disorders. Water Resources: Among the most fundamental effects of climate change is an intensification of the hydrological cycle. Changes in precipitation, and increased evaporation and transpiration due to higher temperatures, can be expected to reduce water runoff, affecting the quantity and quality of water supplies for domestic and industrial uses, irrigation, hydropower generation, navigation, stream ecosystems and water based recreation. These effects will vary region by region. Increased variability in the hydrologic cycle is expected to result in more severe droughts and/or floods in some places. Impacts and mitigation expenses for such events are significant; damage estimates from the Mississippi flood of 1993 range from $10 billion to $20 billion. Areas of greatest vulnerability are those where water supplies and quality are already problems, such as arid and semi-arid regions of the world and some low lying coastal areas, deltas and small islands. Climate change would likely add to the stress in several U.S. river basins, such as the The Colorado River Basin would suffer decreased summer runoff, coinciding with peak Forests: Climate change can dramatically alter the geographic distributions of individual tree species and of forest and vegetation types. One-third of the Earth's forests would undergo a major change in the type of vegetation that could be supported as a result of an equivalent doubling of CO2. In northern forests, which are the forests most vulnerable to climate change, two-thirds of the currently forested area may undergo a change in vegetation type. Mountaintop species and isolated populations are particularly vulnerable. Over the next century, the ideal range for some North American forest species will shift by as much as 300 miles to the north, exceeding the ability of many species to migrate. In some instances, a change in vegetation type will result in a loss of forest area as the land converts to grassland or shrub land, while in other areas forest cover may increase. In the United States, western conifer forests could decrease in area and be replaced by broadleaf forests; eastern hardwood forests may be replaced by grasslands along their western boundary because of mid-continental drying. Forest damage from fire and Other Natural Areas: Natural ecosystems are highly vulnerable to degradation from climate change. Federally protected natural areas have become a repository for the Nation's rarest species and are critical for the conservation of biological diversity. The composition, geographic distribution, and productivity of many ecosystems will shift as individual species respond to changes in climate. These will likely lead to reduction in biological diversity and in the goods and services ecosystems provide for society, such as clean water and recreation. Freshwater wetlands are particularly at risk from climate change. IPCC findings show that: Precipitation changes and salt water intrusion from sea level rise could adversely affect the ecological communities of the Florida Everglades and degrade the habitat for many species of wading birds. The wetlands of the prairie pothole region of North America, which support half the waterfowl population of this continent, could diminish in area and change dramatically in character in response to climate change, significantly exacerbating the destruction already caused by agriculture.. Coastal Areas: Even if concentrations of greenhouse gases are stabilized in the future, sea level would continue to rise long after, perhaps for several centuries, and reach levels much higher than projected for the next 100 years. For example, after an equivalent doubling of CO2, the IPCC expects sea level to rise by 6 - 38 inches over the next century, with a "best estimate" of 20 inches, but the equilibrium sea level rise several centuries in the future is estimated to be at least 6 feet. Rising sea level erodes beaches and coastal wetlands, causes the gradual inundation of low lying areas, leading to human habitat loss and increasing the vulnerability of coastal areas to flooding from storm surges and intense rainfall. The IPCC estimates that 20 inches of sea level rise would double the population at risk from storm surges, from roughly 45 million at present to over 90 million world-wide. A three foot rise would triple the number of people exposed. Increases in coastal area populations are likely to further increase the number of people at risk. Along U.S. coasts, a 20 inch rise could inundate more than 5000 square miles of dry land and an additional 4000 square miles of wetlands if not protective measures are taken. A three foot rise would have greater impact, inundating much of the Southern tip of Florida among other areas. Internationally, low-lying areas, such as parts of the Maldives and Bangladesh, would be completely inundated by a three foot sea level rise, creating large numbers of environmental refugees, which put stress on governments and social structures. 72 million people in China would be affected, assuming existing levels of coastal development. Agriculture and Food Supply: Agriculture is highly dependent on a number of variables that are likely to be affected by climate change, including weather patterns, longer term patterns of climate variability, and, most importantly, water availability. Climate change is likely to lead to increased crop yields in many areas, but decreased yields in others, even for the same crop. The magnitude of these changes can exceed +/- 30 or 40 percent for some crops and locations. Despite these potentially large changes in yields, average global food production is not expected to change substantially. This is because farming practices are considered to be highly adaptable to different climates, because production of important food crops can shift to new locations in response to changes in climate, and because CO, has beneficial effects for plant photosynthesis and water use efficiency that can offset some deleterious effects of changes in climate. Impacts are likely to vary considerably across regions and some regions may suffer substantial reductions in agricultural production. In general, developing countries are more vulnerable to losses than are developed countries. Large reductions in soil moisture could significantly reduce flexibility in crop distribution and increase demands on water resources infrastructure. Increases in the range of pest habitat could increase vulnerabilities to pests and demand for, and use of, pesticides. In the United States, large areas of the eastern and central regions of the country face moderate to severe drying. Drought could become more frequent, particularly in the Great Plains. Conclusion The USGCRP and its companion programs have provided us with a substantial level of understanding of climate change and a substantial body of evidence of the seriousness of this problem and its effects. - The rates of change already imposed on the climate system are faster than any experienced over the last 10,000 years, the time period during which human civilization has developed and modern ecosystems have evolved. Current emissions trajectories, if not altered, could take us before the end of the next century -- a moment in history to an atmospheric concentration of CO, not seen on this planet during the last 50 million years. We cannot preclude some major positive feedback effects -- the collapse of the West Antarctic ice sheet which would cause a 15 foot sea-level rise; the stopping of the ocean conveyor belt which would significantly lower European average temperatures, or the runaway melting in the Arctic which holds frozen several orders of magnitude more carbon than is in the atmosphere today. While much work remains to be done to improve the precision of impact estimates, the increasingly apparent risk of the rapidly changing atmosphere argues that near-term mitigation and adaptation measures are needed. The future plans of the USGCRP are to place an increasing emphasis on providing more detailed understanding of impacts and of the regional variation of change, both of which are directly relevant to crafting effective responses to global climate change. The USGCRP represents a prudent investment in the creation of the knowledge we need to assure a sustainable future. Attachment 1 US Global Change Research Program 1997 Accomplishments A national assessment of the consequences of climate change for the United States was begun during 1997. Eight regional workshops and the U.S. Climate Forum, a major national workshop with over 400 participants, examined the likely consequences of climate change for U.S. regions and ecological and economic sectors. Development of the first global synthesis of information on land cover at a spatial resolution of 1 km (about 0.6 miles) was completed. These data are helping improve understanding of land cover, ocean productivity, and the cycling of carbon through the Earth system, and thus contributing to better predictions of climate change on national and global scales. There was continued improvement in the accuracy and lead times of predictions of seasonal climate fluctuations associated with the El Niño-Southern Oscillation, with several forecasting activities successfully predicted the onset of the 1997-98 El Niño event early enough to support effective flooding mitigation actions. A new 300-site survey of borehole temperatures on four continents produced a detailed record of the climate of the last five centuries and confirmed that the Earth is warming and that the rate of warming has been accelerating rapidly since 1900. Scientists from the NOAA National Climatic Data Center found that 1997 was the warmest year on record since measurements began, and that 9 of the last 11 years are among the warmest on record. Another NOAA analysis showed an average 5-10% increase in the overall amount of U.S. rainfall in the last 100 years. The frequency of heavy downpours, where more than 2 inches of rain falls in a day, has increased by about 20%. Such events lead to flooding, soil erosion and even loss of life. The Tropical Rainfall Measuring Mission (TRMM, a joint NASA-Japanese project) was successfully launched in November of 1997, and is providing rainfall observations that are improving our understanding of the global hydrological cycle and its role in climate change and variability. Ocean productivity images from the SeaStar satellite, launched in 1997 as part of an innovative public-private partnership, are playing a major role in understanding the behavior and consequences of the ongoing El Niño and in other global change research. Following the failure of the Japanese ADEOS spacecraft in mid-1997, NASA successfully changed the orbit of another satellite to allow resumption of near-giobal daily mapping of ozone, as well as stratospheric sulfur dioxide produced from large volcanic eruptions. USGCRP research continued to play a leading role in the Intergovernmental Panel on Climate Change (IPCC) during 1997, and was an important contribution to the IPCC special report entitled The Regional Impacts of Climate Change: An Assessment of Vulnerability and to several IPCC technical papers on other key issues. U.S. citizen Robert T. Watson was elected overall Chair of the IPCC, replacing Bert Bolin of Sweden, and James McCarthy of Harvard University was elected Co-Chair of IPCC Working |