Tuesday, December 7, 2010

US set to see more droughts

Environmental Research Web: Each year the average cost of droughts in the US is around $6–8 bn. Water demand looks set to rise and, together with the uncertain effects of future climate change, this puts water planners under considerable pressure.

Now researchers from the US have found that, while meteorological drought – based on precipitation – is projected to become more frequent in areas such as the southwestern states and less so in other regions, hydrological drought is projected to increase across most of the country. Hydrological drought is based on both precipitation and temperature, which affect the amount of soil moisture.

The team looked at 99 water sub-basins using all 22 general circulation models used by the Intergovernmental Panel on Climate Change (IPCC) under three emissions scenarios and a number of different indices for drought.

"In most of the 99 sub-basins scattered across the country, but particularly for those located in the southwest and the Rocky Mountain States, we find that it is very likely that the frequency of hydrologic drought will increase over the next century," Gary Yohe of Wesleyan University, US, told environmentalresearchweb. "These results are robust across the economic drivers of climate change – as reflected in alternative socio-economic scenarios (three IPCC SRES alternatives) – and the sensitivity of the climate to increased greenhouse-gas concentrations."

…Yohe and colleagues from Massachusetts Institute of Technology, and Industrial Economics Inc say that they are highly confident that impacts caused by hydrologic drought – on agriculture and water availability, for example – will be increasingly negative and widespread over time, despite persistent uncertainty about projected precipitation patterns….

The Mohave Desert in Arizona, shot by Renjishino, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

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