Warming climate may spread drought to a third of earth

Around one third of the earth may be at the greater risk of drought by 2100 as warmer temperatures extract more moisture from the soil, says a study.

The study estimates that 12 percent of land will be subject to drought by 2100 through rainfall changes alone but the drying will spread to 30 percent of land if higher evaporation rates from the added energy and humidity in the atmosphere is considered.

Thus far, concern about future drought under global warming has focused primarily on rainfall projections.

"But higher evaporation rates may also play an important role as warmer temperatures wring more moisture from the soil, even in some places where rainfall is forecasted to increase," cautioned Benjamin Cook, a climate scientist with Columbia University's Lamont-Doherty Earth Observatory and NASA's Goddard Institute for Space Studies.

The study is one of the first to use the latest climate simulations to model the impact of both changing rainfall and evaporation rates on future drought.

"We know from basic physics that warmer temperatures would help to dry things out," Cook added.

In its latest climate report, the International Panel on Climate Change (IPCC) also warns that soil moisture is expected to decline globally and that already dry regions will be at greater risk of agricultural drought.

The IPCC also predicts a strong chance of soil moisture drying in the Mediterranean, southwestern United States and southern African regions, consistent with the Climate Dynamics study.

The study was published in the journal Climate Dynamics.