Water & Climate

Irrigation helps beat the heat


Large-scale irrigation can help alleviate and even reverse hot extremes driven by human activity and other drivers of global warming, a new international study has found.

The research showed that irrigation dampens and, in some cases, offsets the combined effects of global warming on hot days.

Dr Annette Hirsch, from the ANU Research School of Earth Sciences, was part of the research team which was led by ETH Zurich in Switzerland.

She said: “While global warming has increased the chances of hot extremes across the planet, in some regions expanding irrigation reduces that effect or can even reverse it. Irrigation has the same effect for a hotter planet as pumping up the evaporative cooler in your house.”

The study found that in irrigated areas of southern Asia, the practice was up to eight times more likely to reduce the chances of hot extremes.

“This is one of the most populous places on the planet, and means that around one billion people benefit from the heat-reversing effects of irrigation,” said Dr Hirsch, who also holds a position at UNSW. She noted, however, that Australia had yet to see similar benefits.

“Irrigation activity is not as intensive in Australia as southern Asia, so we haven’t seen as strong an influence on heat extremes here,” she said. “But we also know that irrigation in Australia has contracted during periods of drought in recent decades.

“A big question is how this is going to play out in the future, particularly in terms of how rainfall patterns will change and the consequence this has for the water resources we currently use to supply irrigation.”

The research is published in Nature Communications, and was led by Dr Wim Thiery, formerly of ETH Zurich and now based at the University of Brussels.

Source: ANU