Some of the most important crops risk substantial damage from rising temperatures. To better assess how climate change caused by human greenhouse gas emissions will likely impact wheat, maize and soybean, an international team of scientists conducted an unprecedentedly comprehensive set of computer simulations of U.S. crop yields. The simulations reproduced a strong reduction in past crop yields induced by high temperatures, thereby confirming that they capture one main mechanism for future projections. Importantly, the scientists find that increased irrigation can reduce the negative effects of global warming on crops—but this is possible only in regions where sufficient water is available. Eventually, limiting global warming is needed to keep crop losses in check.