Climate change may boost pests, stress food supplies

Global climate change is projected to cause increased pest-related crop losses that could compromise food security for millions, a new study finds.

Why it matters: By focusing on pests, the new research looks at an under-explored aspect of the relationship between climate change and the global food supply. It adds to the findings of previous studies that examined the nutritional content of food as well as changing crop yields.

The details: The new study, published in the journal Science on Thursday, found that as the climate warms, insects' metabolism will speed up, causing them to eat more. In turn, their populations will likely expand.

How they did it: The researchers developed a model based on relationships between temperature and insect physiology and metabolism. They also used current crop yields and their pest-related losses for three staple crops (rice, maize, and wheat), and then added projected monthly and annual surface temperature anomalies from a variety of climate models.

What they found: In total, they found that global yield losses of the three crops will increase by between 10 and 25% per degree of global mean surface warming.

• Together, rice, maize and wheat account for 42% of the direct calories consumed worldwide, the study states.
• The biggest impacts will be felt in the world's maize and wheat breadbaskets located in temperate regions, including the U.S., France, China and Russia. Rice, which is grown in areas that are already warm, will be the least hardest hit, says Curtis A. Deutsch, the lead author of the study and a researcher at the University of Washington.
• Without action to compensate for the increase in pests — including new pest management programs or crop rotation strategies — "insect-driven yield losses will result in reduced global grain supplies and higher staple food prices," the authors write.
• Deutsch said the people who will suffer the most are those already at risk of food insecurity.

"Insect pests currently consume the equivalent of 1 out of every 12 loaves of bread (before it ever gets made)," he said. "By the end of this century, if climate change continues unabated, insects will be eating more than 2 loaves of every 12 that could have been made," he said.

The context: A paper published earlier this week in Nature Climate Change found that elevated levels of carbon dioxide may result in a decline in human nutrition by the middle of this century, based on observations of crops grown in high-carbon dioxide conditions.

• That study found that if carbon dioxide concentrations were to reach 550 parts per million — which is likely under a "business as usual" emissions scenario — then an additional 175 million people would be zinc deficient, and an additional 122 million people would be protein deficient.
• Other studies have shown that crop yields are likely to be diminished as the climate warms, in particular due to an increase in extreme weather events.

What they're saying: Chris Field, the director of Stanford's Woods Institute, told Axios: "The value of this study is its clear demonstration that, based on underlying physiology, there are reasons to expect extra challenges with insects, especially in the temperate breadbasket regions."

Field, who wasn't involved in the new research, says: "There are lots of lines of evidence indicating that climate change will pose additional challenges for crop production (and for people who eat crops)."