Frances Moore

A large literature on “detection and attribution” has now demonstrated the influence of anthropogenic greenhouse gas emissions on a range of physical climate variables. Social and economic outcomes are known to be sensitive to climate change, but directly connecting observed changes to anthropogenic forcing is challenging. Here I estimate the effect of anthropogenic warming on global crop yield trends, showing it is characterized by a general slowing of wheat and maize yields and an acceleration of rice yields in cooler regions. This global, multi-crop signal emerged in the early 2010s from the noise of internal climate variability, uncertainty in the yield response to temperature, and other sources of yield variability. The anthropogenic warming signal is apparent in the observed pattern of yield growth across countries and crops. The net effect has been negative, reducing annual calorie production from these crops by 5.3% on average over the 2008-2017 period, though simple calculations suggest this has likely been fully compensated, at a global level, by gains from CO2 fertilization. This therefore provides early evidence that anthropogenic warming is already having a discernable effect on socio-economic systems at the global scale.