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

precipitation intensities have been found to increase in recent decades in the UK in
the winter, but not in other seasons. Also storminess over the North Atlantic has
increased in recent decades, but storm intensities are not larger than in the beginning
of the 20 th century. The TAR does not explicitly quantified the risk of extreme weather
events in their projections of future climate scenarios, but it is concluded that it is
likely that summer heat waves as well as intense precipitation events, especially in
winter, will become more frequent throughout Europe, especially in winter. Risk of
drought is likely to increase in central and southern Europe. Also gale frequencies
may increase. Flood hazard is projected to increase in much of Europe, except
where snowmelt peaks have been reduced.
Mountain regions
Temperature increases in mountain zones will result in an upward shift of biotic and
cryospheric zones that is likely to lead to a perturbation of their sensitive ecosystems.
The most spectacular effect of temperature rises in areas at high elevation is the
melting of glaciers, but also tree line rises and changes in vegetation have been
observed. Observations in the Swedish Scandes have shown tree line rises of up to
150-165 m (Kullman, 2001) and saplings of mountain birch, spruce and pine have
recently become established 500-700 m over their current tree limits (Kullman, 2004).
The upward migration of tree species is projected to continue, but there are some
uncertainty regarding how fast this will take place and how far it will go. The TAR
concludes that the redistribution of species caused by climate change in mountain
regions will cause a risk of extinction in some cases.
Projected changes for mountain regions suggest that the European Alps are likely to
have slightly warmer winters with more precipitation than previously while the
summer climate may become much warmer and drier than today (Beniston, 1995). 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.
II.2. Impacts in European Coastal Areas
Sea level rise
The sea level rise predicted under the scenarios considered in the TAR for European
regional climate change is in the range between 13 and 68 cm by the 2050s, mainly
due to thermal expansion of the oceans. This estimate does not include the effects of
vertical land-movements that are adjustments after the last glaciation nor effects of
oceanic circulation, which will cause some differences in relative sea-level change
across Europe. Regional values, e.g. at European Coasts, can be 50% higher or
lower (UKCIP02, 2003). Sea level rise of 0.5 to 2m are expected after the climate
system will be in equilibrium with a CO2 concentration of 560 ppmV (twice the preindustrial
concentration), but this will happen over several hundreds of years.
As mentioned earlier, the predictions by the IPCC are ‘conservative’ in the sense that
they consider only snowfall, sublimation and melting and do not incorporate nonlinear
processes and feedbacks that, according to other studies, may enhance deglaciation
very significantly and possibly cause sea level rises of several meters over a century
(Hansen, 2003). If these, more pessimistic, predictions are correct, sea-level rise
may well become the globally most important climate change-related problem. A
rising sea level possibly combined with more frequent storms and associated surges
are likely to cause enhanced coastal erosion (see Section IV.C). Whether the effects
of the recent tsunamis in the Indian Ocean were exacerbated by sea level rise is
unlikely.
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