by Alex Kirby, Climate News Network, January 11, 2014
LONDON - With exquisite timing, as parts of Europe endure the worst storms for decades, researchers have issued a highly topical warning.
By the end of this century, they say, summer temperatures in parts of southern Europe are expected to be up to 5 °C higher than they were from 1961 to 1990, with droughts inevitably becoming more frequent and intense, because of both climate change and increased water use.
The researchers, from the European Commission’s Joint Research Centre (JRC) and the University of Kassel in Germany, have published their findings in Hydrology and Earth System Sciences, an open-access journal of the European Geosciences Union (EGU). The scientific article is available online, free of charge.
“Our research shows that many river basins, especially in southern parts of Europe, are likely to become more prone to periods of reduced water supply due to climate change,” says Giovanni Forzieri, a researcher in climate risk management at the JRC and lead author of the study. In Europe the cost of drought over the last three decades has totalled over €100 billion (£83 bn).
The researchers wanted to find out if and where in Europe increasing temperatures and intensive water consumption could make future droughts more severe and long-lasting.
Marked regional differences
To do this they analysed climate and hydrological models under different scenarios up to 2100. They then used these projected conditions to drive a hydrological model that mimics the distribution and flow of water on Earth. By running this model until 2100 for all river basins in Europe, they could evaluate how drought conditions may change in magnitude and severity over the 21st century.
The research shows that southern Europe will be the most affected. Stream and river minimum flow levels may be up to 40% lower, with periods of water shortage up to 80% more frequent because of climate change alone in the Iberian Peninsula, the south of France, Italy and the Balkans.
Higher temperatures will result in more water evaporating from soil, trees and water and will also mean more frequent and prolonged dry spells. The emission scenario used in the study predicts that average global temperature will increase by up to 3.4 °C by 2100 above the years 1961 to 1990.
But regional rises are liable to be significantly greater, as for example in the case of the Iberian Peninsula, says Luc Feyen, a hydrologist at JRC and co-author of the paper.
Apart from climate warming, intensive water use will also worsen drought conditions by 10-30% in southern Europe, as well as in the west and centre of the continent, and in some parts of the UK.
In 2010 a study by the US National Center for Atmospheric Research projected serious drought impacts by the 2030s, and suggested those by the end of the century could surpass anything in the historical record.
In 2012 a report by the European Environment Agency, "Vulnerability to Water Scarcity and Drought in Europe - ETC/ICM Technical Report 3/2012," said there had been an observable increase in the number of countries affected by drought each decade from 1971 to 2011.
The occurrence of drought had increased significantly in the decade from 2001, not only in southern and central parts of the European Union, but in the northern and eastern parts of the bloc as well.