River floods are the most common natural disaster in Europe. Noteworthy recent examples include the catastrophic floods in central Europe in August 2002; flooding in Romania and the Alpine countries in August 2005; along the Elbe and Danube in March and April 2006; and the severe summertime flooding in Britain in 2007. Although there is as yet no proof that the extreme flood events that struck Europe in recent years are a direct consequence of climate change, they may give an indication of what can be expected.

Change in average flood magnitude with 100-year recurrence interval between 1961-1990 and 2071-2100 for SRES A2 scenario. The average is derived from an ensemble of climate predictions (see Dankers and Feyen, 2009)

Change in average flood magnitude with 100-year recurrence interval between 1961-1990 and 2071-2100 for SRES B2 scenario. The average is derived from an ensemble of climate predictions (see Dankers and Feyen, 2009)

 
Results from a multi-model, multiple-realisation and multi-scenario approach show that in the coming decades global warming is projected to increase the magnitude and frequency of floods in some major European rivers such as the Loire, Garonne and Rhone in France, the Po in Italy and the Danube in central and eastern Europe. In areas with a seasonal snow cover, mostly in the northeastern part of the continent, a general decrease in extreme discharge levels is projected. This suggests a reduction in the hazard of extreme snowmelt floods.

Impact of climate change on flood risk

Floods can result in huge economic losses due to damage to infrastructure, property and agricultural land, and indirect losses in or beyond the flooded areas, such as production losses caused by damaged stock or roads, or the interruption of power generation and navigation. Flood risk is defined as the product of flood probability or hazard, exposure of capital and population, and vulnerability to the effect of flooding. Flood hazard information is transformed into direct monetary damage estimates using country specific flood depth-damage functions and land use information. Population exposure is assessed by overlaying the flood inundation information with data on population density. 

Relative change in Expected Annual Damage (averaged over administrative level NUTS2) between scenario (2071-2100) and control period (1961-1990) for the IPCC SRES A2 scenario (see Feyen et al., 2009).

Relative change in Expected Annual Damage (averaged over administrative level NUTS2) between scenario (2071-2100) and control period (1961-1990) for the IPCC SRES B2 scenario.

Results indicate that, under the SRES A2 and B2 scenarios, flood damages are projected to rise across much of western, central and eastern Europe, as well as in Italy and northern parts of Spain. The strongest decrease in flood damage is projected for the north-eastern parts of Europe. For EU27 as a whole, current EAD of approximately €6.5 billion is projected to reach €18 billion (in constant prices of 2006) under the A2 scenario and €14 billion under the B2 scenario by the end of this century. By the end of this century, EAP is projected to rise from approximately 200,000 to 520,000 and 470,000 under the A2 and B2 scenario, respectively. Hence, the annual benefit of action aggregated at EU27 level amounts to €4 billion and 50,000 people less exposed (see Feyen et al., 2009).