Dustbowl Blues

October 12, 2010

A new study carries bad news for huge areas of the world. Hell, given its implications, it seems facile to restrict its importance to those places that aren’t directly affected. As scientists working on the FLUXNET synthesis project report, soils around the world as drying up fast.

Climate models had predicted that rising temperatures due to CO2 emissions would result in increased evapotranspiration, as water evaporated from the land and entered the atmosphere. In some places, scientists predicted that this would increase rainfall, offsetting the drying effect. But, as the study published in Nature has found, in many places, such evapotranspiration stopped abruptly from 1998 after a twenty year rise. Since then some soils have become drier and drier.

Why has this been so? A press release from the team involved notes that “one possibility is that on a global level, a limit to the acceleration of the hydrological cycle on land has already been reached.” That is, in some places – clustered in the Southern Hemisphere – the atmosphere may not be able to absorb more water via evapotranspiration than is currently the case.

Climate scientists usually assume that evapotranspiration will increase for far longer. If so, the results could be catastrophic – increased drought, heat waves, die back of tropical vegetation and forest fires.

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