Crops and rising atmospheric CO: friends or foes?

Rising atmospheric carbon dioxide concentration ([CO]) is a ubiquitous global change with direct and indirect impacts on crops. The increase in atmospheric [CO] since the industrial revolution has stimulated photosynthesis in crops and reduced stomatal conductance and canopy transpiration. These physiological changes result in a "CO fertilization effect" contributing to greater crop yields. However, CO is a greenhouse gas and has been the major contributor to increased radiative forcing and warmer global temperatures, resulting in more extreme weather events, with negative consequences for crop production. While the benefits of rising [CO] have stimulated productivity to date, they may soon be outweighed by the challenges of rising temperatures and altered precipitation on plant productivity. Rising atmospheric [CO] also reduces the nutritional value of crops, reducing protein content and the concentration of key micronutrients. Distinct physiological mechanisms contribute to changes in crop nutritional value at elevated [CO], but there is potential to harness genetic diversity in nutrient content and for biofortification to counteract the negative impacts of rising [CO] on crop quality. Crop improvement strategies that both adapt crops to future environments and mitigate the negative environmental impacts of agriculture are critical to ensuring future agricultural and nutritional sustainability.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.