This report describes an assessment of the effects of climate policy on the crop productivity and food security. The study had two components. The first used a crop simulation model to simulate the effect of climate change on maize productivity. The second used these results, with earlier simulations of change in spring wheat and soybean productivity, to estimate the effects of climate change on the number of undernourished people.
Unmitigated climate change leads to reductions of maize productivity of between 20 and 50% by 2050 compared to present productivity, with variation between regions. The effect of climate change is greater on maize productivity than on productivity of either spring wheat or soybean, because maize benefits less from increased atmospheric CO2 concentrations.
Climate policy reduces, but does not eliminate, the adverse impact of climate change on maize productivity. A policy with emissions peaking in 2016 reduces the impacts of climate change by between 10 and 20% by 2050, and 25-40% by 2100 (in other words, by the end of the 21st century the climate policy only avoids between 25 and 40% of the impacts of climate change). This is of a similar order of magnitude to the avoided impacts on spring wheat and soybean productivity, although there is less regional variability. Adaptation to climate change, in the form of changing crop varieties, increases slightly the effect of climate policy on impacts.
In the absence of continued agricultural innovation and changes in agricultural trade, population and economic growth would mean that an additional 28% of global population would be at risk of undernourishment by 2050 – around 2.5 billion people. This number represents a crop production and utilisation deficit. Climate change adds approximately 1.7 billion people by 2050, with the number varying only slightly between climate models. A climate policy with emissions peaking in 2016 reduces the impact of climate change only by around 5% in 2050, rising to 8-18% in 2080, and 16-26% in 2100; later peaking results in an even smaller impact. There is considerable variation in avoided impacts between regions.