Executive Summary

• Climate Change. Climate model projections suggest a general increase in temperature, greatest in northerly latitudes. Precipitation changes are considerably more uncertain, but one could expect generally wetter conditions in the north, drier conditions in the south, and increasingly drier conditions from west to east. Winter precipitation may be greater than today, while summer precipitation is likely to decrease.
• Sensitive Regions. As water is one of the main integrating factors for many environmental and economic systems in Europe, currently sensitive areas in terms of their hydrology include the Mediterranean region, the Alps, northern Scandinavia, certain coastal zones, and central and eastern Europe. A changing climate is likely to enhance water-related stresses in these already sensitive regions.

Vulnerability and Potential Impacts

Hydrology, Snow and Ice, Water Supply and Demand

• Evapotranspiration will increase in a warmer climate, with potential reductions in water availability; however, the response of hydrological systems depends on the distribution of precipitation (highly variable, as suggested above) and storage capacity.
• Many regions in the southern and interior parts of Europe could experience a general decrease in runoff, though the change in runoff may range between -5% and +12%.
• More droughts could be expected in southern Europe, and the potential for winter and springtime flooding could be greater in northern and northWestern Europe. However, this pattern is not the same for all general circulation models (GCMs).
• Intrusion of saline waters into coastal aquifers and the expected reduction in precipitation could aggravate the problem of freshwater supply in some areas.
• Snow and ice are likely to decrease in many places, with consequences for the timing and amount of runoff in river basins, as well as winter tourism.
• Demand for water could increase in summer. Supply could decrease, though there may be regional differences in which storage capacity plays an important role.
• Pollution is a major stress factor for many European rivers, and a decrease in discharge would increase pollutant concentrations, leading to reductions in water quality.
• Current national and international policies and practices for water resources management will be put under stress by climate change.

Ecosystems

• With the exception of parts of Scandinavia and the Russian Federation, Europe has few genuine natural ecosystems. Natural ecosystems generally are confined to poor soils and are fragmented and disturbed; consequently, they tend to be more sensitive to climate change than agriculture, which occupies the most fertile soils.
• The reaction of European ecosystems to global change is difficult to predict because there are a number of interactions and feedback loops between increasing temperatures, decreasing availability of soil water, and increasing carbon dioxide (CO₂) concentrations.
• Increasing CO₂ concentration increases the productivity of plants with C₃ metabolism under laboratory conditions (for most agricultural plants, except maize and millet). However, many other factors come into play under field conditions, such as water and nutrient stress, increased respiration losses, and interactions between species. Therefore, the overall change in productivity can only be predicted if these interacting environmental conditions are taken into account. Many studies indicate that CO₂ increases alone may have relatively little impact under field conditions.
• The forests in many parts of Europe are affected by high deposition rates of nitrogen. Their productivity is not only a function of climatic factors but of the change in nitrogen deposition, which can both act as a fertilizer and cause disturbances to many processes within the ecosystem.

Agriculture

• Crop mixes and production zones will be redistributed, and the use of water, fertilizers, herbicides, and pesticides will shift with them.
• Conflicting demands for water-for instance, between irrigation and domestic supply in southern Europe-will need to be taken into account.
• Changes in potential production translate in a complex way to farmer incomes and food prices, depending on technology, farmer adaptation, world markets, and agricultural policies.

Coastal Zones

• Sea-level rise will place additional stress on coastal zones already stressed by other factors (urbanization, coastal developments, pollution, etc.).
• The level of impact will depend on the adaptation capacity (e.g., the ability of systems to move inland) and policies of individual countries (e.g., trade-offs between lands that are not considered important and those that need to be protected).
• Sensitive zones include areas already close to or below mean sea level (such as the Dutch and German North Sea coastlines, the Po River delta, and the Ukrainian Black Sea coast), areas with low intertidal variation (such as the coastal zones of the Baltic Sea and the Mediterranean), and coastal wetlands.
• Changes in the nature and frequency of storm surges, particularly in the North Sea, are likely to be of considerable importance for low-lying coastal areas.

Other Infrastructure, Activities, Settlements

• Energy. Changing hydrology will impact those energy and industrial production sectors that depend on water for cooling. There is a potential for increased energy demand related to cooling in summer, and decreased energy demand related to heating in winter. Such changes would lead to shifts in peak energy demand.
• Urbanization. Infrastructure, buildings, and cities designed for cooler climates will have to be adjusted to warmer conditions, particularly heat waves, to maintain current functions.

Health

• While there are fewer heat-related deaths in Europe than in some other parts of the world, the risk of heat-related deaths would probably increase with summer warming. The risk of cold-related deaths would probably decline with winter warming. It is not clear what the net change in risk would be for Europe.
• Warmer temperatures will exacerbate summer air pollution episodes and their health impacts in many cities.
• Some vector-borne infectious diseases will have the potential to extend their range; the adaptation capacity of individual countries will depend on their level of environmental management, public health surveillance, and health care.

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