Science Update: the ‘wet gets wetter, dry gets drier’ trend

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A recent publication in Nature Climate Change (Donat et al, 2016) has significant implications for future water management on the Canadian Prairies.   The influence of a warming planet on precipitation patterns is a central question that climatologists must address to guide policies for climate adaptation.

Over the ocean,  climatologists generally agree that regions of the ocean with high precipitation already will get wetter, while dry parts of the ocean will see less precipitation; the ‘wet gets wetter, dry gets drier’ trend.  Essentially, where evaporation already exceeds precipitation net evaporation will increase, and net precipitation will increase where it dominates at present.

On land the extent to which this trend applies has been less clear until recently. Using Global Circulation Model results from the Coupled Model Inter-comparison Project Phase 5 (the same data ensemble that underlies the Prairie Climate Atlas), Markus Donat and his colleagues show that the ‘wet gets wetter, dry gets drier’ trend does indeed hold over wet and dry regions of the continents, with one important caveat: both wet and dry regions can expect more extreme rainfall events. In dry regions  this means that a large fraction of  annual precipitation may fall in only a few days.

The Canadian Prairies are a generally a sub-humid to semi-arid region, generally cool enough to support rainfed agriculture – if the trend is indeed towards greater aridity and more extreme precipitation events then the logic of using retention storage becomes an ever more important adaptation strategy as we will need to harvest increasingly precious precipitation.

 

Read more at Nature Climate Changehttp://www.nature.com/nclimate/journal/v6/n5/full/nclimate2941.html

 

– Dr. Hank Venema, IISD