Sequential heat extremes amplify food production losses

When heat hits twice

As the climate warms, extreme weather increasingly occurs in sequence. The study led by Vrije Universiteit (VU) Amsterdam, ETH Zurich, and IIASA, together with coauthors from institutions across Europe and the United States and published in Environmental Research Letters, shows that such back-to-back heat events pose a serious threat to global food production.

The study shows that early-season heat can raise yield potential but leaves crops more vulnerable to subsequent heatwaves during the flowering period. Across maize, soybean, wheat, and barley in the US and Europe, spring heat leads to 5–55 % larger losses from summer heat, compared to years with average spring conditions.

“Early heat can act like a double-edged sword,” says Carmen B. Steinmann, environmental scientist at ETH Zurich. “While it may boost yield potential at first, it leaves crops far more vulnerable when summer heat strikes,” adds Raed Hamed, postdoctoral researcher at the VU Amsterdam.

Rising risks, avoidable losses

“Today, warm springs generally benefit yields, but this could change”, explains Raed Hamed, lead author of the study. “Under high-emission scenarios, we project that additional yield losses from sequential heat will offset potential benefits of warmer springs.”

By the end of the century, sequential heat events could become up to ten times more frequent if emissions remain high. Accounting for this interaction increases projected yield losses by an additional 2–44%, offsetting potential benefits of warmer springs. Limiting global warming to 1.5°C reduces projected losses to just 1–6%.

“Our results underline how crucial rapid climate action is to avoid societal impacts from increasingly complex climate risks,” emphasizes IIASA senior research scholar Kai Kornhuber.

Insights for resilient food systems

The study highlights the need to consider compounding climate extremes to strengthen food system resilience. By bridging detailed physiological insights from laboratory experiments with large-scale statistical analysis, it also provides guidance for climate adaptation planning.

Reference

Hamed, R., Steinmann, C.B., Ma, Q., Balanzategui, D., Broadman, E., Lesk, C., Kornhuber, K. (2025). Amplified agricultural impacts from more frequent and intense sequential heat events. Environmental Research Letters DOI: https://doi.org/10.1088/1748-9326/ae06b8