A study published in Environmental Research Letters shows that the world may face a small but substantially increased risk over the next two decades of a major slowdown in the growth of global crop yields because of climate change. The authors, from Stanford University and the National Center for Atmospheric Research (NCAR), say the odds of a major production slowdown of wheat and corn even with a warming climate are not very high. But the risk is about 20 times more significant than it would be without global warming, and it may require planning by organizations that are affected by international food availability and price.
The researchers used simulations available from an NCAR-based climate model, as well as several other models, to provide trends in temperature and precipitation over the next two decades for crop-intensive regions under a scenario of increasing carbon dioxide. They also used the same model simulations without human-caused increases in carbon dioxide to assess the same trends in a natural climate. In addition, they ran statistical analyses to estimate the impacts of changes in temperature and precipitation on wheat and corn yields in various regions of the globe and during specific times of the year that coincide with the most important times of the growing seasons for those two crops.
The researchers quantified the extent to which warming temperatures would correlate with reduced yields. For example, an increase of 1°C (1.8°F) would slow corn yields by 7% and wheat yields by 6%. Depending on the crop-growing region, the odds of such a temperature increase in the next 20 years were about 30–40% in simulations that included increases in carbon dioxide. In contrast, such temperature increases had a much lower chance of occurring in simulations that included only natural variability, not human-induced climate change.
Although society could offset the climate impacts by planting wheat and corn in cooler regions, such planting shifts to date have not occurred quickly enough to offset warmer temperatures, the study warned. The authors also found little evidence that other adaptation strategies, such as changes in crop varieties or growing practices, would totally offset the impact of warming temperatures.