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

It is realized that adaptation to climate change – that is the ‘ability ... to adjust to
climate changes (including climate variability and extremes) to moderate potential
damages….or to cope with consequences’ (IPCC, 2001) – should be a key issue.
Possible adaptation options can be taken in populated areas that involve the
planning of settlements and their infrastructure, placement of industrial facilities etc.
in a manner to reduce the negative effects of events and to forecast and minimize
potential damages.
V.A.3. Main expected effects for extreme floods and droughts
“(Monthly) Runoff tends to increase in northern Europe, and decrease in the south.
Percentage increases are up to 25% and decreases may be as great as 50%”
(Arnell, 1999). “Low flows tend to be reduced in maritime parts of Europe, as summer
flows decline, but may increase (in winter) in more continental parts of Europe” This
is because of a shift of snowfall to rainfall and increased snowmelt during winters in
these continental areas, which have now low winter runoff.
“During summer months, Southern Europe is expected to become drier while
Northern Europe will probably get wetter” (Vellinga and Van Verseveld, 2000).
“Flood magnitude and frequency are likely (a 66-90% probability) to increase in most
regions, and low flows are likely to decrease in many regions” (IPCC-McCarthy et al,
2001).
Palmer and Räisänen (2002) find that in the winter over Europe, the probability of
extremely high seasonal precipitation increases by about two to five times over the
course of the next 50 to 100 years.
Simulations by Schar et al. (2004) suggested that, towards the end of this century,
every second summer in Europe could be as hot and dry as the summer of 2003.
They write: "The European summer climate might experience a profound increase in
year-to-year variability in response to greenhouse forcing. Such an increase might be
able to explain the unusual European summer of 2003, and would strongly affect the
incidence of heatwaves and droughts in the future."
In addition to the direct effects, increased heat stress and lower soil moisture
availability will increase the demand for water resources in summer, leading higher
rates of water abstraction from stream flows and groundwater that in turn might
decrease low flows and lower the groundwater table.
Known gaps and questions
Schnur (2002) stated that today's climate models are not good at predicting extreme
climate events in local areas, such as flooding in a given river basin, because they
are limited in their resolution to a coarse grid size of about 200 kilometres. For the
average river basin, climate-change simulations would need a much higher resolution
of tens of kilometres, but this will not be available for quite some time.
Burlando (2004) goes even further and states that climate change analysis on water
resources needs to be done at the catchment scale, preferably at sizes of 1km2 or
even smaller, which is the scale where weather variability and landscape variability
reaches manageable proportions.
Until these high-resolution climate change simulations are available, downscaling
methods need to be applied to produce the proper spatial resolution needed for
119