Researchers Strengthen Projections of Climate’s Impacts on Agriculture

Climate-change impact assessments help scientists to identify and quantify the risks to the world’s food supply, as well as to evaluate adaptation and mitigation strategies. An international team of agro-climatic experts has now narrowed the range of possible impacts by evaluating experimental and modeling research on the effects of elevated carbon dioxide concentrations on crops. Their findings were just reported in the journal Nature Food. The evaluation was organized by the Agricultural Model Intercomparison and Improvement Project (AgMIP) and the Joint Research Commission (JRC) of the European Union.

Recent efforts and the accumulated evidence, concluded the team, are such that scenarios that exclude the effects of CO₂ can finally be eliminated from climate change impact assessments. Previously, modelers have usually employed scenarios that both include and exclude the effects of elevated atmospheric CO₂ on crops. That was because the uncertainties were considered too high to exclude one of the two. Now, the uncertainties can be narrowed in assessments that are used to inform policymakers and to design future strategies, say the paper’s authors.

AgMIP, whose coordinating unit is based at Columbia University, is a community of experts advancing methods for improving predictions on the future performance of agricultural and food systems under a changing climate. Cynthia Rosenzweig and Erik Mencos Contreras of Columbia’s Center for Climate Systems Research are coauthors on the new paper.

Cynthia Rosenzweig, a co-leader of AgMIP, said, “No more with, and without, CO_2.  CO₂ has important effects on crops both in their yields and quality that now must be taken into account in global and regional assessments. This will help decision-makers across the entire food system to prepare more effectively for the changing climate.”

The team also identified key uncertainties and knowledge gaps that still remain, especially on the nutritional effects of the climate on crops, and on the complex effects of climate extremes. The paper proposes a roadmap for the coming years to support targeted experimental and modeling research.

The paper concludes a two-year process carried out by the team, started during a workshop on the effects of CO₂ on crops co-organized by AgMIP and the JRC in 2018.