New research has found that irrigation can help fight against hot weather extremes. South Asia benefits in particular.
Large-scale irrigation can have a strong effect on climate conditions, and especially hot extremes, according to a recently published study in Nature Communications.
In the study, an international team of researchers examined the influence of irrigation on global warming by using observational data and global climate simulations to isolate the climatic effects of irrigation from warming induced by other climatic drives, such as greenhouse gas emissions.
They found that irrigation can provide effective cooling during warm extremes in intensely irrigated regions such as Southern Europe, North Africa, South Asia and the United States. In South Asia in particular, the cooling effect of irrigation partly or completely offset the more frequent and intense heat extremes brought on my global warming.
“This means that, while global warming increases the likelihood of hot extremes almost globally, in some regions, irrigation expansion cancels or even reverses this effect”, said Wim Thiery, who participated in the research while he was a postdoc at the Swiss Federal Institute of Technology in Zurich. He has since taken up an assistant professorship at the University of Brussels.
Although the results validated that irrigation substantially reduced human exposure to warming of hot extremes, the study is less certain whether this benefit will continue in the future given that diminishing groundwater reserves and retreating glaciers may decrease water supply for irrigation in the long term.
Should this occur, irrigation-induced cooling might level off, leading to accelerated warming across the irrigation hotspots.
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