Global Vulnerability of Crop Yields to Climate Change
Agricultural adaptation to climate change will be critical to future food security. Using high-resolution weather records in conjunction with a longitudinal gridded dataset of yields of five crops that supply more than two-thirds of global dietary energy, we statistically estimate a dynamic empirical model that distinguishes farmers' net-of-adaptation responses to temperature and precipitation shocks in the short-run (weather) and the long run (climate) in different agroclimatic zones across the globe. Climate change impacts on yields and calorie supplies are assessed by combining empirically modeled responses with changes in exposure to different temperature and precipitation regimes circa 2050 and 2090, calculated from simulations of 21 climate models. In a vigorous warming (RCP 8.5) scenario, even as early as mid-century yields of most calorie crops decline in more than 75% of the places where they are cultivated. Adverse impacts over the long run show only slight attenuation—and in a few cases amplification—relative to those in the short run, highlighting the global nature of limits to agricultural adaptation. Yield declines vary with differential shifts in temperature and precipitation exposures across locations as opposed to among climate simulations, which exhibit substantial agreement on yield reductions of 3-12% circa 2050 and 11-25% circa 2090.
Increasing extreme heat and declining rainfall in major crop-growing regions will reduce the supply of calories needed to sustain the world’s growing population. Prior research that even U.S. farmers have limited capacity to adapt to extreme heat bodes ominously for future yields of food crops in countries with less developed agricultural systems—particularly in the tropics where 40% of the world’s population live and high-temperature extremes are projected to rise more than in the U.S. Our findings suggest cause for concern: worldwide, adverse responses of yields to high temperatures and low precipitation are only slightly smaller over the long run compared to the short run, a phenomenon that portends substantial reductions in global calorie supply. Yield responses and global gridded multi-model projections of impacts generated by this study facilitate further research to identify and address barriers to adaptation and investigate the multi-sector consequences of the agricultural impacts of climate change, for the U.S. as well as its major trade partners.
Using a newly available panel dataset of gridded annual crop yields in conjunction with a dynamic econometric model that distinguishes between farmers' short-run and long-run responses to weather shocks and accounts for adaptation, we investigate the risk to global crop yields from climate warming. Overbroad spatial domains we observe only slight moderation of short-run impacts by farmers' long-run adjustments. In the absence of additional margins of adaptation beyond those pursued historically, projections constructed using an ensemble of 21 climate model simulations suggest that climate change could reduce global crop yields by 3–12% by mid-century and 11–25% by century's end, under a vigorous warming scenario.