Farmers in focus: Effects of elevated CO2 concentration on crops

 
Agriculture is a key socio-economic sector that both influences the climate and is exposed to climate impacts. To reach targets on food security, protection of biodiversity and the natural environment as well as on climate mitigation for the global common land, it is crucial to know how and where climate change and increasing atmospheric concentrations of CO2 affect crops. Decision makers and farmers need to quantify the risks to their sector and evaluate sustainable adaptation and mitigation strategies. An international team of agro-climatic experts, including PIK researcher Christoph Müller, has reviewed existing crop models that are used for these climate change risk assessments: While the size of CO2 fertilization effects is still uncertain to some extent, their results, published in Nature Food today, suggest that presenting crop modelling results without accounting elevated CO2 simulations are obsolete and don't offer added value to decision makers.
Farmers in focus: Effects of elevated CO2 concentration on crops
Giessen Free-Air CO2 Enrichment Facility in Germany. Picture: Gerald Moser (University of Giessen)

Modelling has usually been carried out for scenarios that both include and exclude the effects of elevated atmospheric CO2 concentrations on crops, as the uncertainties were considered too high to exclude one of the two. An international team of agro-climatic experts, led by Andrea Toreti (European Commission, Joint Research Centre JRC, Ispra) and Delphine Deryng (NewClimate Institute/IRI THESys, Humboldt-Universität zu Berlin), collected and evaluated experimental and modelling research on the effects of elevated CO2 concentrations on crops. The team concluded that recent efforts and the accumulated evidence are such that scenarios that exclude the effects of elevated CO2 can finally be eliminated from climate change impact assessments.

Putting an end to misinterpreted models

"Presenting scenarios that do not consider CO2 effects on plant growth as plausible future projections have been causing confusion in the public debate. Our study shows that crop models need to be improved, especially at high levels of CO2, to better understand the threat of climate change to agricultural production and how much land can be made available for other purposes, such as nature conservation or land-based climate mitigation measures", explains Christoph Müller, researcher from the Potsdam Institute for Climate Impact Research (PIK).

This represents a fundamental step towards improving the communication of climate change impact assessments for agriculture, while laying out strategies for further narrowing the uncertainties. These assessments are used to inform policymakers, as well as to design future adaptation and mitigation pathways.  The team also identified key uncertainties and knowledge gaps that still remain, especially on nutritional aspects and on the complex effects of climate extremes. Therefore, the paper proposes a roadmap for the coming years to support targeted experimental and modelling research.

Article:

Andrea Toreti, Delphine Deryng, Francesco N. Tubiello, Christoph Muller, Bruce A. Kimball, Gerald Moser, Ken Boote, Senthold Asseng, Thomas A. M. Pug, Eline Vanuytrecht, Hakan Pleijel, Heidi Webber, Jean-Louis Durand, Frank Dentener, Andrej Ceglar, Xuhui Wang, Frank Badeck, Remi Lecerf, Gerard W. Wall, Maurits van den Berg, Petra Hoegy, Raul Lopez-Lozano, Matteo Zampieri, Stefano Galmarini, Garry J. O'Leary, Remy Manderscheid, Erik Mencos Contreras, Cynthia Rosenzweig: Narrowing uncertainties in the effects of elevated CO2 on crops. Nature Food.
[DOI:10.1038/s43016-020-00195-4]





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