Daniel Patrick Bebber , Carole Dalin, Emma Littleton, Pete Falloon, Andrew Challinor, Steve McCorriston, Tim Lloyd, Matteo Zampieri

Climate change is increasing the risk of extreme weather events, potentially threatening crop yields and global food security. A key benefit of international free trade is risk sharing, because global aggregate production is more stable than that of individual countries which may be adversely affected by extremes. Here we test the hypothesis that diverse sourcing of crops from multiple trading partners reduces exposure to extreme weather, using a detailed trade matrix and range of extreme weather indices. We find that countries with high source diversity have moderate exposure, but that there is wide variation in the degree of exposure in countries reliant on domestic crop production. Global aggregate production and export volatility is stable or declining for most crops, suggesting that source diversification will increase resilience to both climatic and non-climatic supply shocks.