December 15, 2017.
Vulnerabilities - Switzerland
It seems likely that alpine climate change will lead to changes in timing and amount of run-off in European river basins and that floods and droughts will become more frequent. The projected decline in precipitation in the Alps plus rise in temperature could produce a 40-70% reduction in runoff. Summer discharge of Alpine catchments will significantly decrease and winter floods will become more frequent. Because the Alps are the primary source for such major rivers as the Rhine, Rhone, Po, and Danube, the impact of reduced mountain precipitation would be felt far beyond the mountainous regions themselves (17).
The definition of drought
Drought is a natural phenomenon defined as sustained and extensive occurrence of below average water availability. Drought should not be confused with aridity, which is a long-term average feature of a dry climate. It is also distinct from water scarcity, which constitutes an imbalance between water availability and demand (1).
Three general types of drought may be recognized (7):
Vulnerabilities in Europe
The European Commission has estimated that at least 11 % of Europe's population and 17 % of its territory have been affected by water scarcity to date and put the cost of droughts in Europe over the past thirty years at EUR 100 billion (1).The drought of 2003 caused a total economic cost of over €13 billion in around twenty European countries (2,7).
Vulnerabilities - European trends in the past
There is no clear evidence that a widespread change in droughts has occurred in Europe over the last century or over the last decades (6). There is no evidence that river flow droughts have become more severe or frequent over Europe in general in recent decades (3), nor is there conclusive proof of a general increase in summer dryness in Europe over the past 50 years due to reduced summer moisture availability (4). Strong increases in the area of combined severe dry and wet conditions in Europe over the last three decades have also been identified, though, and it has been suggested that without global warming droughts would have been smaller and less pervasive (13).
Vulnerabilities - Future projections for Europe
In 2012 the IPCC concluded that there is medium confidence in a projected increase in duration and intensity of droughts in some regions of the world, including southern Europe and the Mediterranean region, and central Europe (18).
River flow droughts are projected to increase in frequency and severity in southern and south-eastern Europe, the United Kingdom, France, Benelux, and western parts of Germany over the coming decades. In snow-dominated regions, where droughts typically occur in winter, river flow droughts are projected to become less severe because a lower fraction of precipitation will fall as snow in warmer winters. In most of Europe, the projected decrease in summer precipitation, accompanied by rising temperatures which enhances evaporative demand, may lead to more frequent and intense summer droughts (9).
Europe should view 2003 as a wake-up call. The 2003 drought should be the catalyst for actions aimed at reducing drought impacts across all relevant sectors (7). Drought is not mentioned in European energy policies. Similarly European transport navigation policy makes no reference to low flow conditions, whereas health policies make few provisions for reduced water supplies and deteriorating water quality. Drought is one criterion for exemption to the requirements of the Water Framework Directive - an increasingly likely situation. It makes no provision for managing biodiversity protection during severe droughts (7).
In contrast to internal policy, drought is addressed as a real issue in EU development policies. Drought is seen as a threat to sustainable development, a humanitarian issue and a driver of mass migration and political instability (7).
Adaptation activities currently seem to be focused on flood management and defence, while adaptation measures related to the management of water scarcity and drought, although recognized as equally damaging, do not yet seem to be widespread (2).