Climate Change and the European Water Dimension - Agri ...

Figure V.A.1. A map showing the number of times more likely it is that a European
winter will be extremely wet in 50 to 100 years, compared with today. Source: Palmer
and Räisänen (2002).
Milly et al. (2002) examined the historical occurrence of hundred-year floods on
large-scale river basins around the world and then used climate models to assess
whether the observed behavior was related to an enhanced greenhouse effect, as
well as to surmise what we may expect in the future. As for the historical record, they
found that a greater frequency of hundred-year floods occurred in the latter half of
their record than in the early half. The trend they found in hundred-year flood
occurrence over the 20th century was 1.99 x 10 -4 events per year, which means a
trend that results in one extra hundred-year flood every 5,000 years! They have
identified this trend in climate models run with 20th-century conditions, but also found
that this trend will continue, and perhaps even grow into the future (using models
incorporating rates of greenhouse enhancement that are about twice the current
observed values).
Vellinga and Van Verseveld (2000) conclude that “as concentrations of greenhouse
gases in the atmosphere continue to rise, it is likely that there will be an increase in
the intensity of rainstorms, river floods, droughts, and other extreme weather events.”
The World Water Council (2003) states that “the expected climatic change during the
21st century will further intensify the hydrological cycle, with rainy seasons becoming
shorter and more intense in some regions, while droughts in other areas will grow
longer in duration, which could endanger species and crops and lead to drops in food
production globally. The risk of more frequent, and possibly more brutal, storms,
extreme weather events will increase”. “Economic losses from weather and flood
catastrophes have increased ten-fold over the past 50 years, partially the result of
rapid climate changes. These rapid climate changes are seen in more intense rainy
seasons, longer dry seasons, stronger storms, shifts in rainfall and rising sea levels.
More disastrous floods and droughts have been the most visible manifestation of
these changes.”
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