Warming of hot extremes alleviated by expanding irrigation

• Published in: Nature communications Vol. 11; no. 1; pp. 290 - 7
• Main Authors: Thiery, Wim, Visser, Auke J., Fischer, Erich M., Hauser, Mathias, Hirsch, Annette L., Lawrence, David M., Lejeune, Quentin, Davin, Edouard L., Seneviratne, Sonia I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.01.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/694/1108; 704/106/694/674; 704/242; Anthropogenic factors; Attribution; BASIC BIOLOGICAL SCIENCES; Climate and Earth System Modelling; Climate change; Climate effects; Climatic conditions; ENVIRONMENTAL SCIENCES; GEOSCIENCES; Global warming; Humanities and Social Sciences; Hydrology; Irrigation; Irrigation effects; multidisciplinary; Science; Science & Technology - Other Topics; Science (multidisciplinary); South Asia
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-14075-4

Irrigation affects climate conditions – and especially hot extremes – in various regions across the globe. Yet how these climatic effects compare to other anthropogenic forcings is largely unknown. Here we provide observational and model evidence that expanding irrigation has dampened historical anthropogenic warming during hot days, with particularly strong effects over South Asia. We show that irrigation expansion can explain the negative correlation between global observed changes in daytime summer temperatures and present-day irrigation extent. While global warming increases the likelihood of hot extremes almost globally, irrigation can regionally cancel or even reverse the effects of all other forcings combined. Around one billion people (0.79–1.29) currently benefit from this dampened increase in hot extremes because irrigation massively expanded throughout the 20 t h century. Our results therefore highlight that irrigation substantially reduced human exposure to warming of hot extremes but question whether this benefit will continue towards the future. How the effects of irrigation on the climate conditions compare to other anthropogenic forcings is not well known. Observational and model evidence show that expanding irrigation has dampened historical anthropogenic warming during hot days, an effect that is particularly strong over South Asia.