Global scale climate–crop yield relationships and the impacts of recent warming

Abstract

Changes in the global production of major crops are important drivers of food prices, foodsecurity and land use decisions. Average global yields for these commodities aredetermined by the performance of crops in millions of fields distributed across arange of management, soil and climate regimes. Despite the complexity of globalfood supply, here we show that simple measures of growing season temperaturesand precipitation—spatial averages based on the locations of each crop—explain∼30% or more of year-to-year variations in global average yields for the world’s six most widelygrown crops. For wheat, maize and barley, there is a clearly negative response of globalyields to increased temperatures. Based on these sensitivities and observed climate trends,we estimate that warming since 1981 has resulted in annual combined losses of these threecrops representing roughly 40 Mt or $5 billion per year, as of 2002. While these impacts aresmall relative to the technological yield gains over the same period, the results demonstratealready occurring negative impacts of climate trends on crop yields at the globalscale.