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may represent significant costs for large industries. Human Health: Some degree of vulnerability is apparent. Indigenous communities and the economically disadvantaged may be more at risk. Increases are expected in heat-stress mortality, vector-borne diseases such as dengue, water and sewagerelated diseases, and urban pollution-related respiratory problems. Though small compared with the total burden of ill health, these impacts have the potential to cause considerable community impact and cost.

Conclusions: Australia's relatively low latitude makes it particularly vulnerable to impacts on its scarce water resources and on crops growing near or above their optimum temperatures, whereas New Zealand's cooler, wetter, mid-latitude location may lead to some benefit through the ready availability of suitable crops and likely increases in agricultural production. In both countries, however, there is a wide range of situations where vulnerability is thought to be moderate to high-particularly in ecosystems, hydrology, coastal zones, human settlements and human health.

6.5 Europe

Europe constitutes the western part of the Eurasian continent. Its eastern boundary is formed by the Ural Mountains, the Ural River, and part of the Caspian Sea. The proximity of the relatively warm Gulf Stream and typical atmospheric circulation contribute to the large spatial and temporal variability of the region's temperature and precipitation. South of the main Alpine divide, the climate is of the Mediterranean type.

Ecosystems: Natural ecosystems generally are fragmented, disturbed and confined to poor soils. This situation makes them more sensitive to climate change. Mediterranean and boreal grasslands may shift in response to changes in the amount and the seasonal distribution of precipitation. The northern boundaries of forests in Fennoscandia and northern Russia would likely expand into tundra regions, reducing the extent of tundra, mires and permafrost areas. Survival of some species and forest types may be endangered by the projected movement of climate zones at rates faster than migration speeds. Highelevation ecosystems and species are particularly vulnerable because they have nowhere to migrate. An increase in temperature, accompanied by decreases in soil moisture, would lead to a substantial reduction in peat formation in Fennoscandian and northern Russian peatlands. Thawing of the permafrost layer would lead to lowered water tables in some areas and would flood thaw lakes in others, altering current wetland ecosystem types. Although the diversity of freshwater species may increase in a warmer climate, particularly in middle and high latitudes, there may be an initial reduction in species diversity in cool temperate and boreal regions. Ecosystems in southern Europe would be threatened mainly by reduced precipitation and subsequent increases in water scarcity.

Hydrology and Water Resources: Most of Europe experienced temperature increases this century larger than the global aver

age, and enhanced precipitation in the northern half and decreases in the southern half of the region. Projections of future climate, not taking into account the effect of aerosols, indicate that precipitation in high latitudes of Europe may increase, with mixed results for other parts of Europe. The current uncertainties about future precipitation are mainly exacerbated by the effects of aerosols.

Water supply may be affected by possible increases in floods in northern and northwest Europe and by droughts in southern portions of the continent. Many floodplains in western Europe already are overpopulated, which hampers effective additional flood protection. Pollution is a major problem for many rivers; a warmer climate could lead to reduced water quality, particularly if accompanied by reduced runoff. Warmer summers would lead to increased water demand, although increased demand for irrigation would be at least partly offset for many crops by increased water-use efficiency associated with CO2 fertilization.

Expected changes in snow and ice will have profound impacts on European streams and rivers. Up to 95 per cent of Alpine glacier mass could disappear by 2100, with subsequent consequences for the water flow regime-affecting, for example, summer water supply, shipping and hydropower. Also, in some areas, winter tourism would be negatively affected.

Water management is partly determined by legislation and cooperation among government entities, within countries and internationally; altered water supply and demand would call for a reconsideration of existing legal and cooperative arrangements.

Food and Fiber Production: Risks of frost would be reduced in a warmer climate, allowing winter cereals and other winter crops to expand to areas such as southern Fennoscandia and western Russia. Potential yields of winter crops are expected to increase, especially in central and southern Europe, assuming that neither precipitation nor irrigation are limiting and that water-use efficiency increases with the ambient atmospheric concentration of CO2. Increasing spring temperatures would extend suitable zones for most summer crops. Summer crop yield increases are possible in central and eastern Europe, though decreases are possible in western Europe. Decreases in precipitation in southern Europe would reduce crop yields and make irrigation an even larger competitor to domestic and industrial water use. Along with potential crop yields, farmer adaptation, agricultural policy and world markets are important factors in the economic impact of climate change on the agricultural sector.

Coastal Systems: Coastal zones are ecologically and economically important. Settlement and economic activity have reduced the resilience and adaptability of coastal systems to climate variability and change, as well as to sea-level rise. Some coastal areas already are beneath mean sea level, and many others are vulnerable to storm surges. Areas most at risk include the Dutch, German, Ukrainian and Russian coastlines; some Mediterranean deltas; and Baltic coastal zones. Storm surges, changes in precipitation, and changes in wind speed and direc

tion add to the concern of coastal planners. In general, major economic and social impacts can be contained with relatively low investment. This is not true, however, for a number of lowlying urban areas vulnerable to storm surges, nor for ecosystems-particularly coastal wetlands-which may be even further damaged by protective measures.

Human Settlements: Supply and demand for cooling water will change. Energy demand may increase in summer (cooling) and decrease in winter (heating), and peak energy demand will shift. Infrastructure, buildings and cities designed for cooler climates will have to be adjusted to warming, particularly heat waves, to maintain current functions. In areas where precipitation increases or intensifies, there are additional risks from landslides and river floods.

Human Health: Heat-related deaths would increase under global warming and may be exacerbated by worsening air quality in cities; there would be a reduction in cold-related deaths. Vector-borne diseases would expand. Health care measures could significantly reduce such impacts.

Conclusions: Even though capabilities for adaptation in managed systems in many places in Europe are relatively well established, significant impacts of climate change still should be anticipated. Major effects are likely to be felt through changes in the frequency of extreme events and precipitation, causing more droughts in some areas and more river floods elsewhere. Effects will be felt primarily in agriculture and other water-dependent activities. Boreal forest and permafrost areas are projected to undergo major change. Ecosystems are especially vulnerable due to the projected rate of climate change and because migration is hampered.

Latin America includes all continental countries of the Americas from Mexico to Chile and Argentina, as well as adjacent seas. The region is highly heterogeneous in terms of climate, ecosystems, human population distribution and cultural traditions. Several Latin American countries-especially those of the Central American isthmus, Ecuador, Brazil, Peru, Bolivia, Chile and Argentina are significantly affected with adverse socioeconomic consequences by seasonal to interannual climate variability, particularly the ENSO phenomenon. Most production is based on the region's extensive natural ecosystems, and the impacts of current climate variability on natural resources suggest that the impacts of projected climate changes could be important enough to be taken into account in national and regional planning initiatives. Land use is a major force driving ecosystem change at present, interacting with climate in complex ways. This factor makes the task of identifying common patterns of vulnerability to climate change very difficult.

Ecosystems: Large forest and rangeland areas are expected to be affected as a result of projected changes in climate, with mountain ecosystems and transitional zones between vegeta

tion types extremely vulnerable. Climate change could add an additional stress to the adverse effects of continued deforestation in the Amazon rainforest. This impact could lead to biodiversity losses, reduce rainfall and runoff within and beyond the Amazon basin (reduced precipitation recycling through evapotranspiration), and affect the global carbon cycle.

Hydrology and Water Resources: Climate change could significantly affect the hydrological cycle, altering the intensity and temporal and spatial distribution of precipitation, surface runoff and groundwater recharge, with various impacts on different natural ecosystems and human activities. Arid and semi-arid areas are particularly vulnerable to changes in water availability. Hydropower generation and grain and livestock production are particularly vulnerable to changes in water supply, particularly in Costa Rica, Panama and the Andes piedmont, as well as adjacent areas in Chile and western Argentina between 25°S and 37°S. The impacts on water resources could be sufficient to lead to conflicts among users, regions and countries.

Food and Fiber Production: Decreases in agricultural production -even after allowing for the positive effects of elevated CO2 on crop growth and moderate levels of adaptation at the farm level-are projected for several major crops in Mexico, countries of the Central American isthmus, Brazil, Chile, Argentina and Uruguay. In addition, livestock production would decrease if temperate grasslands have to face substantial decreases in water availability. Extreme events (e.g., floods, droughts, frosts, storms) have the potential to adversely affect rangelands and agricultural production (e.g., banana crops in Central America). The livelihoods of traditional peoples, such as many Andean communities, would be threatened if the productivity or surface area of rangelands or traditional crops is reduced.

Coastal Systems: Losses of coastal land and biodiversity (including coral reefs, mangrove ecosystems, estuarine wetlands, and marine mammals and birds), damage to infrastructure, and saltwater intrusion resulting from sea-level rise could occur in low-lying coasts and estuaries in countries such as those of the Central American isthmus, Venezuela, Argentina and Uruguay. Sea-level rise that blocks the runoff of flatland rivers into the ocean could increase the risks of floods in their basins (e.g., in the Argentine Pampas).

Human Settlements: Climate change would produce a number of direct and indirect effects on the welfare, health, and security of the inhabitants of Latin America. Direct impacts resulting from sea-level rise, adverse weather and extreme climatic conditions (e.g., floods, flash floods, windstorms, landslides, and cold and heat outbreaks), as well as indirect effects through impacts on other sectors such as water and food supply, transportation, energy distribution and sanitation services, could be exacerbated by projected climate change. Particularly vulnerable groups include those living in shanty towns in areas around large cities, especially where those settlements are established in flood-prone areas or on unstable hillsides.

Human Health: Projected changes in climate could increase the

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Ecosystems: Most ecosystems are moderately to highly sensitive to changes in climate. Effects are likely to include both beneficial and harmful changes. Potential impacts include northward shifts of forest and other vegetation types, which would affect biodiversity by altering habitats and would reduce the market and non-market goods and services they provide; declines in forest density and forested area in some subregions, but gains in others; more frequent and larger forest fires; expansion of arid land species into the great basin region; drying of prairie pothole wetlands that currently support over 50 per cent of all waterfowl in North America; and changes in distribution of habitat for cold-, cool- and warm-water fish. The ability to apply management practices to limit potential damages is likely to be low for ecosystems that are not already intensively managed.

Hydrology and Water Resources: Water quantity and quality are particularly sensitive to climate change. Potential impacts include increased runoff in winter and spring and decreased soil moisture and runoff in summer. The Great Plains and prairie regions are particularly vulnerable. Projected increases in the frequency of heavy rainfall events and severe flooding also could be accompanied by an increase in the length of dry periods between rainfall events and in the frequency and/or severity of droughts in parts of North America. Water quality could suffer and would decline where minimum river flows decline. Opportunities to adapt are extensive, but their costs and possible obstacles may be limiting.

resources of North America is moderately to highly sensitive to climate change. Most studies, however, have not fully considered the effects of potential changes in climate variability; water availability; stresses from pests, diseases and fire; or interactions with other, existing stresses. Warmer climate scenarios (4-5°C increases in North America) have yielded estimates of negative impacts in eastern, southeastern and corn belt regions and positive effects in northern plains and western regions. More moderate warming produced estimates of predominately positive effects in some warm-season crops. Vulnerability of commercial forest production is uncertain, but is likely to be lower than less intensively managed systems due to changing technology and management options. The vulnerability of food and fiber production in North America is thought to be low at the continental scale, though subregional variation in losses or gains is likely. The ability to adapt may be limited by information gaps; institutional obstacles; high economic, social and environmental costs; and the rate of climate change.

Coastal Systems: Sea level has been rising relative to the land along most of the coast of North America, and falling in a few areas, for thousands of years. During the next century, a 50-cm rise in sea level from climate change alone could inundate 8 500 to 19 000 km2 of dry land, expand the 100-year floodplain by more than 23 000 km2 and eliminate as much as 50 per cent of North America's coastal wetlands. The projected changes in sea level due to climate change alone would underestimate the total change in sea level from all causes along the eastern seabord and Gulf coast of North America. In many areas, wetlands and estuarine beaches may be squeezed between advancing seas and dikes or seawalls built to protect human settlements. Several local governments are implementing land-use regulations to enable coastal ecosystems to migrate landward as sea level rises. Saltwater intrusion may threaten water supplies in several areas.

Human Settlements: Projected changes in climate could have positive and negative impacts on the operation and maintenance costs of North American land and water transportation. Such changes also could increase the risks to property and human health and life as a result of possible increased exposure to natural hazards (e.g., wildfires, landslides and extreme weather events) and result in increased demand for cooling and decreased demand for heating energy-with the overall net effect varying across geographic regions.

Human Health: Climate can have wide-ranging and potentially adverse effects on human health via direct pathways (e.g., thermal stress and extreme weather/climate events) and indirect pathways (e.g., disease vectors and infectious agents, environmental and occupational exposures to toxic substances, food production). In high-latitude regions, some human health impacts are expected due to dietary changes resulting from shifts in migratory patterns and abundance of native food sources.

simultaneously and in concert with changes in population, technology, economics, and other environmental and social changes, however, adds to the complexity of the impact assessment and the choice of appropriate responses. The characteristics of subregions and sectors of North America suggest that neither the impacts of climate change nor the response options will be uniform.

Many systems of North America are moderately to highly sensitive to climate change, and the range of estimated effects often includes the potential for substantial damages. The technological capability to adapt management of systems to lessen or avoid damaging effects exists in many instances. The ability to adapt may be diminished, however, by the attendant costs, lack of private incentives to protect publicly owned natural systems, imperfect information regarding future changes in climate and the available options for adaptation, and institutional barriers. The most vulnerable sectors and regions include longlived natural forest ecosystems in the east and interior west; water resources in the southern plains; agriculture in the southeast and southern plains; human health in areas currently experiencing diminished urban air quality; northern ecosystems and habitats; estuarine beaches in developed areas; and lowlatitude cool- and cold-water fisheries. Other sectors and subregions may benefit from opportunities associated with warmer temperatures or, potentially, from CO2 fertilization-including west coast coniferous forests; some western rangelands; reduced energy costs for heating in the northern latitudes; reduced salting and snow-clearance costs; longer open-water seasons in northern channels and ports, and agriculture in the northern latitudes, the interior west and the west coast.

With the exception of Malta and Cyprus in the Mediterranean, all of the small island states considered here are located within the tropics. About one-third of the states comprise a single main island; the others are made up of several or many islands. Low-lying island states and atolls are especially vulnerable to climate change and associated sea-level rise because in many cases (e.g., the Bahamas, Kiribati, the Maldives, the Marshall Islands), much of the land area rarely exceeds 3-4 m above present mean sea level. Many islands at higher elevation also are vulnerable to climate change effects, particularly in their coastal zones, where the main settlements and vital economic infrastructure almost invariably are concentrated.

Ecosystems: Although projected temperature rise is not anticipated to have widespread adverse consequences, some critical ecosystems, such as coral reefs, are very sensitive to temperature changes. Although some reefs have the ability to keep pace with the projected rate of sea-level rise, in many parts of the tropics (e.g., the Caribbean Sea, the Pacific Ocean) some species of corals live near their limits of temperature tolerance. Elevated seawater temperatures (above seasonal maxima) can seriously damage corals by bleaching and also impair their reproductive functions, and lead to increased mortality. The

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adaptive capacity of mangroves to climate change is expected to vary by species, as well as according to local conditions (e.g., the presence or absence of sediment-rich, macrotidal environments, the availability of adequate fresh water to maintain the salinity balance). The natural capacity of mangroves to adapt and migrate landward also is expected to be reduced by coastal land loss and the presence of infrastructure in the coastal zone. On some islands, ecosystems already are being harmed by other anthropogenic stresses (e.g., pollution), which may pose as great a threat as climate change itself. Climate change would add to these stresses and further compromise the long-term viability of these tropical ecosystems.

Hydrology and Water Resources: Freshwater shortage is a serious problem in many small island states, and many such states depend heavily on rainwater as the source of water. Changes in the patterns of rainfall may cause serious problems to such nations.

Coastal Systems: Higher rates of erosion and coastal land loss are expected in many small islands as a consequence of the projected rise in sea level. In the case of Majuro atoll in the Marshall Islands and Kiribati, it is estimated that for a 1-m rise in sea level as much as 80 per cent and 12.5 per cent (respectively) of total land would be vulnerable. Generally, beach sediment budgets are expected to be adversely affected by reductions in sediment deposition. On high islands, however, increased sediment yield from streams will help to compensate for sand loss from reefs. Low-lying island states and atolls also are expected to experience increased sea flooding, inundation and salinization (of soils and freshwater lenses) as a direct consequence of sea-level rise.

Human Settlements and Infrastructure: In a number of islands, vital infrastructure and major concentrations of settlements are likely to be at risk, given their location at or near present sea level and their proximity to the coast (often within 1-2 km; e.g., Kiribati, Tuvalu, the Maldives, the Bahamas). Moreover, vulnerability assessments also suggest that shore and infrastructure protection costs could be financially burdensome for some small island states.

Human Health: Climate change is projected to exacerbate health problems such as heat-related illness, cholera, dengue fever and biotoxin poisoning, and would place additional stress on the already over-extended health systems of most small islands.

Tourism: Tourism is the dominant economic sector in a number of small island states in the Caribbean Sea and the Pacific and Indian Oceans. In 1995, tourism accounted for 69 per cent, 53 per cent, and 50 per cent of gross national product (GNP) in Antigua, the Bahamas and the Maldives, respectively. This sector also carns considerable foreign exchange for a number of small island states, many of which are heavily dependent on imported food, fuel and a range of other vital goods and services. Foreign exchange earnings from tourism also provided more than 50 per cent of total revenues for some countries in 1995. Climate change and sea-level rise would affect tourism

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directly and indirectly: loss of beaches to erosion and inundation, salinization of freshwater aquifers, increasing stress on coastal ecosystems, damage to infrastructure from tropical and extra-tropical storms, and an overall loss of amenities would jeopardize the viability and threaten the long-term sustainability of this important industry in many small islands.

Conclusions: To evaluate the vulnerability of these island states to projected climate change, a fully integrated approach to vulnerability assessments is needed. The interaction of various biophysical attributes (e.g., size, elevation, relative isolation) with the islands' economic and sociocultural character ultimately determines the vulnerability of these islands. Moreover, some islands are prone to periodic nonclimate-related hazards (e.g., earthquakes, volcanic eruptions, tsunamis); the overall vulnerability of these islands cannot be accurately evaluated in isolation from such threats. Similarly, vulnerability assessments for these small island states should take into consideration the value of nonmarketed goods and services (e.g., subsistence assets, community structure, traditional skills and knowledge), which also may be at risk from climate change. In some island societies, these assets are just as important as marketed goods and services. Uncertainties in climate change projections may discourage adaptation, especially because some options may be costly or require changes in societal norms and behavior. As a guiding principle, policies and development programmes which seek to use resources in a sustainable manner, and which can respond effectively to changing conditions such as climate change, would be beneficial to the small island states, even if climate change did not occur.

forests and shrublands. Some model studies suggest that in a doubled CO2 climate there would be a large reduction in the area (up to 50 per cent) and productivity of boreal forests (primarily in the Russian Federation), accompanied by a significant expansion of grasslands and shrublands. There also would be a decrease in the area of the tundra zone of as much as 50 per cent-accompanied by the release of methane from deep peat deposits and an increase (less than 25 per cent), in CO2 emissions.

Hydrology and Water Resources: Overall, most 2×CO2 equilibrium scenario simulations show a decrease in water supply. except in a few river basins. Warmer winters may affect water balances because water demands are higher in spring and summer. Equilibrium climate conditions for doubled equivalent CO2 concentrations indicate that a decrease of as much as 25 per cent in mountain glacier mass is possible by 2050. Initially, runoff from glaciers in central Asia is projected to increase threefold by 2050, but by 2100 glacier runoff would taper to two-thirds of its present value. Model results suggest that runoff in the northern part of China is quite vulnerable to climate change, mainly as a consequence of changes in precipitation in spring, summer and autumn, especially during the flood season. To balance water supply with water demand, increasingly efficient water management is likely the best approach for Japan. In other parts of Temperate Asia, water-resource development will remain important; the central adaptation issue is how the design of new water-resource infrastructure should be adjusted to account for uncertainties resulting from climate change. The most critical uncertainties are the lack of credible projections of the effects of global change on the Asian monsoon or the ENSO phenomenon, which have great influence on river runoffs. Multiple-stress impact studies on water resources in international river basins are needed in the future.

Food and Fiber Production: Projected changes in crop yields using climate projections from different GCMs vary widely. In China, for example, across different scenarios and different sites, the changes for several crop yields by 2050 are projected to be: rice, -78 per cent to +15 per cent; wheat, -21 per cent to +55 per cent; and maize, -19 per cent to +5 per cent. An increase in productivity may occur if the positive effects of CO2 on crop growth are considered, but its magnitude remains uncertain. A northward shift of crop zones is expected to increase agricultural productivity in northern Siberia but to decrease (by about 25 per cent) grain production in southwestern Siberia because of a more arid climate. Aquaculture is particularly important to Temperate Asia. Greater cultivation of warm-water species could develop. Warming will require greater attention to possible oxygen depletion, fish diseases, and introduction of unwanted species, as well as to potential negative factors such as changes in established reproductive patterns, migration routes and ecosystem relationships.

Coastal Systems: An increase in sea level will exacerbate the current severe problems of tectonically and anthropogenically induced land subsidence in delta areas. Saltwater intrusion also