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

and water resources (EEA, 2004). Finally, a rise of the mean sea level between 13
and 68 cm is projected by 2050.
Presently agriculture is the dominant user of abstracted water in southern countries.
Under climate change conditions, it is expected that irrigation water demand will
further increase in those areas, aggravating the competition with other sectors whose
demand is also projected to increase (Parry, 2000). In addition, an expected lowering
of the groundwater table will make irrigation more expensive, which, in turn might
have to be limited to cash crops. In parallel, a general increase in agricultural and
domestic water requirements is projected, putting additional pressure on the
groundwater resources. Extreme weather events such as heat waves will impact on
peak irrigation requirements (see, for example, Beniston 2004 for a discussion of the
2003 heat wave). As the evaporative demand will increase due to higher
temperatures, it is expected that capillary rise will increase the salinisation of soils,
having a major impact on irrigation management. Salinisation might also occur in
coastal aquifers due to sea level rise and aquifer depletion, causing salt-water
intrusion.
Döll (2002) used a global irrigation model at 0.5° by 0.5° resolution to evaluate the
change in irrigation requirements under climate change scenarios as calculated by
two Global Circulation Models (GCMs). For Europe she predicted an increase in net
irrigation requirements of about 6% for the 2020s, and of about 9% for the 2070s as
compared to the baseline scenario (1961-1990), including large regional differences.
While a drop of net irrigation requirements from 771 mm/year to 701 mm/year in the
2020s is predicted for in western Spain, irrigation requirements are predicted to
increase in southeast England from 77 to 120 mm/year.
Lehner et al. (2001) predicted an increase of water withdrawal from 415 km 3 /year in
1995 to 660 km 3 /year in the years around 2070 (63% increase), with the irrigation
abstraction increasing from 142 to 146 km 3 /year (less than 3% increase). In general,
one could have expected larger changes, especially in the southern countries, where
irrigation is important. However, the expected improvements in water use efficiency
are larger than the expected decrease in water availability due to climate change.
The result could be an overall decrease of water withdrawn for irrigation. At the same
time many unknown factors such as changes in the irrigated areas; changes in crop
varieties and their regional distribution could heavily influence the results of such
predictions.
Fischer et al. (2002) evaluated the impact of several climate change scenarios on
environmental constraints to crop production. They considered soil constraints such
as soil depth, fertility, texture, drainage, and salinity/sodicity. Climate constraints
included the length of cold spells and dry spells. The evolution of severe
environmental constraints from the baseline scenario (1961-1990) to the HaDCM3
scenario (2080s) is summarised in Table V.D.2.
Table V.D.2 shows that climate change will introduce a drop in the areas affected by
severe conditions for rain-fed crops in Northern Europe by 7%, while there is an
increase in the areas affected by severe constraints in the South. Table V.D.2 clearly
illustrates that in Northern Europe “too cold” constraints will disappear, while there is
an increase of the constraints due to “poor soil”, which can partly be explained by the
disappearance of cold conditions as a limiting factor. For the Southern regions, there
is an increase in the area affected by the “too dry” condition.
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