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Global wheat production with 1.5 and 2.0°C above pre-industrial warming

Abstract: 
Efforts to limit global warming to below 2°C in relation to the pre-industrial level are under way, in accordance with the 2015 Paris Agreement. However, most impact research on agriculture to date has focused on impacts of warming >2oC on mean crop yields, and many previous studies did not focus sufficiently on extreme events and yield interannual variability. Here, with the latest climate scenarios from the Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI) project, we used a multi-crop and multi-climate model ensemble over a global network of sites developed within the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Team to represent major rainfed and irrigated systems, and evaluated the impacts of the 2015 Paris Agreement range of global warming (1.5oC and 2.0oC warming above the pre-industrial period) on global wheat production and local yield variability. Results show that projected global wheat production will change by -2.3% to 7.0% under the 1.5 scenario and -2.4% to 10.5% under the 2.0 scenario, compared to a baseline of 1980-2010, when considering changes in local temperature, rainfall and global atmospheric CO2 concentration, but no changes in management or wheat cultivars. The projected impact on wheat production varies spatially; a larger increase is projected for temperate high rainfall regions than for moderate hot low rainfall and irrigated regions. Grain yields in warmer regions are more likely to be reduced than in cooler regions. Despite mostly positive impacts on global average grain yields, the frequency of extremely low yields (bottom 5 percentile of baseline distribution) and yield inter-annual variability will increase under both warming scenarios for some of the hot growing environments, including the second largest global wheat producer –India, which supplies more than 14% of global wheat. The projected global impact of warming <2oC on wheat production are therefore not evenly distributed and will affect regional food security across the globe as well as food prices and trade.