Drought potential worldwide in 21st century - Aiguo Dai, NCAR

Related news: http://www2.ucar.edu/news/2904/climate-change-drought-may-threaten-much-globe...

NCAR scientist Aiguo Dai examined the potential for future drought worldwide during the 21st century. His study is based on current projections of future greenhouse gas emissions. The visualization is not intended as a forecast, since the actual course of projected greenhouse gas emissions as well as natural climate variations could alter future drought patterns.

Regions that are blue or green will likely be at lower risk of drought, while those in the yellow and red spectrum could face more unusually-extreme drought conditions.

The projection uses a common measure, the Palmer Drought Severity Index, or PDSI, which assigns positive numbers when conditions are unusually wet for a particular region, and negative numbers when conditions are unusually dry.

Dai turned to results from the 22 computer models used by the IPCC in its 2007 report to gather projections about temperature, precipitation, humidity, wind speed, and Earth's radiative balance, based on current projections of greenhouse gas emissions. He then fed the information into the Palmer model to calculate the PDSI.

A reading of +0.5 to -0.5 on the index indicates normal conditions, while a reading at or below -4 indicates extreme drought. The index ranges from +10 to -10 for current climate conditions, although readings below -6 are exceedingly rare, even during short periods in small areas.

(Credit: UCAR. Visualization by Tim Scheitlin, Mary Haley, and Ryan McVeigh, NCAR. Based on Dai, 2010, Wiley Interdisciplinary Reviews: Climate Change.)

An earlier version of this simulation, without audio narration and with data ending in 2098, was published on YouTube in October 2010 (http://youtu.be/MePAro1PsiI)

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• climate change
• global warming
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• Aiguo Dai
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