Regional disparities in the beneficial effects of rising CO₂ concentrations on crop water productivity

Summary, in English

Rising atmospheric CO₂ concentrations ([CO₂ ]) are expected to enhance photosynthesis and reduce crop water use. However, there is high uncertainty about the global implications of these effects for future crop production and agricultural water requirements under climate change. Here we combine results from networks of field experiments and global crop models to present a spatially explicit global perspective on crop water productivity (CWP, the ratio of crop yield to evapotranspiration) for wheat, maize, rice and soybean under elevated [CO₂ ] and associated climate change projected for a high-end greenhouse gas emissions scenario. We find CO₂ effects increase global CWP by 10[0;47]%-27[7;37]% (median[interquartile range] across the model ensemble) by the 2080s depending on crop types, with particularly large increases in arid regions (by up to 48[25;56]% for rainfed wheat). If realized in the fields, the effects of elevated [CO₂ ] could considerably mitigate global yield losses whilst reducing agricultural consumptive water use (4-17%). We identify regional disparities driven by differences in growing conditions across agro-ecosystems that could have implications for increasing food production without compromising water security. Finally, our results demonstrate the need to expand field experiments and encourage greater consistency in modelling the effects of rising [CO₂ ] across crop and hydrological modelling communities.

• Author: Delphine Deryng; Joshua Elliott; Christian Folberth; Christoph Müller; Thomas A M Pugh; Kenneth J. Boote; Declan Conway; Alex C. Ruane; Dieter Gerten; James W. Jones; Nikolay Khabarov; Stefan Olin; Sibyll Schaphoff; Erwin Schmid; Hong Yang; Cynthia Rosenzweig
• Department/s: Dept of Physical Geography and Ecosystem Science; MERGE: ModElling the Regional and Global Earth system; BECC: Biodiversity and Ecosystem services in a Changing Climate
• Publishing year: 2016-08-01
• Language: English
• Pages: 786-790
• Publication/Series: Nature Climate Change
• Volume: 6
• Issue: 8
• Links: http://dx.doi.org/10.1038/nclimate2995
• Document type: Journal article
• Publisher: Nature Publishing Group
• Topic: Climate Research
• Status: Published
• ISBN/ISSN/Other: ISSN: 1758-678X