Increase in crop losses to insect pests in a warming climate      
Deutsch et al., 2019

Crop responses to climate warming suggest that yields will decrease as growing-season temperatures increase. Deutsch et al. show that this effect may be exacerbated by insect pests. Insects already consume 5 to 20% of major grain crops. The authors' models show that for the three most important grain crops—wheat, rice, and maize—yield lost to insects will increase by 10 to 25% per degree Celsius of warming, hitting hardest in the temperate zone. These findings provide an estimate of further potential climate impacts on global food supply and a benchmark for future regional and field-specific studies of crop-pest-climate interactions.

Insect pests substantially reduce yields of three staple grains—rice, maize, and wheat—but models assessing the agricultural impacts of global warming rarely consider crop losses to insects. We use established relationships between temperature and the population growth and metabolic rates of insects to estimate how and where climate warming will augment losses of rice, maize, and wheat to insects. Global yield losses of these grains are projected to increase by 10 to 25% per degree of global mean surface warming. Crop losses will be most acute in areas where warming increases both population growth and metabolic rates of insects. These conditions are centered primarily in temperate regions, where most grain is produced.

Global loss of crop production owing to the impact of climate warming on insect pests. Crop production losses for (A) wheat, (B) rice, and (C) maize are computed by multiplying the fractional change in population metabolism by the estimated current yield loss owing to insect pests, summed over worldwide crop locations. Results are plotted versus mean global surface temperature change, for four climate models, for two different values of the demographic parameter governing survival during diapause (ϕ_o = 0.0001, asterisks; ϕ_o = 0.001, circles), and for the metabolic effect alone (triangles). Mt/yr, metric megatons per year. The year in which a given global mean temperature anomaly is reached (D) depends on the greenhouse gas emissions scenario (RCP, representative concentration pathway) and varies across models (shading) owing to uncertainty in climate sensitivity to those emissions.

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