Narrowing uncertainties in the effects of elevated CO 2 on crops.

Plant responses to rising atmospheric carbon dioxide (CO 2 ) concentrations, together with projected variations in temperature and precipitation will determine future agricultural production. Estimates of the impacts of climate change on agriculture provide essential information to design effective adaptation strategies, and develop sustainable food systems. Here, we review the current experimental evidence and crop models on the effects of elevated CO 2 concentrations. Recent concerted efforts have narrowed the uncertainties in CO 2 -induced crop responses so that climate change impact simulations omitting CO 2 can now be eliminated. To address remaining knowledge gaps and uncertainties in estimating the effects of elevated CO 2 and climate change on crops, future research should expand experiments on more crop species under a wider range of growing conditions, improve the representation of responses to climate extremes in crop models, and simulate additional crop physiological processes related to nutritional quality.