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Agriculture: using cover crops to mitigate the effects of climate change

In Europe, around 20% of land surface area is covered by agricultural fields. During fallow periods, soils often remain bare. Researchers from the National Centre of Meteorological Research (CNRM, Météo-France/CNRS/University of Toulouse) and the Centre for the Study of the Biosphere from Space (CESBIO, University of Toulouse III—Paul Sabatier/ CNRS/CNES/IRD/INRA) recently published a study in a special issue of Environmental Research Letters dedicated to climate change. In it, they quantify how cover crops could be used during fallow periods to mitigate the effects of climate change. Simulations suggest this strategy could compensate for up to 7% of the greenhouse gas emissions released by the agricultural industry in Europe.

field. © INRA
Updated on 10/17/2018
Published on 04/12/2018

To fight climate change, current methods for limiting greenhouse gas emissions and/or moderating their effects are insufficient. Therefore, to meet the new temperature target established during COP 21 (< 2°C increase), climate engineering may therefore become necessary. Climate engineering techniques focus on removing atmospheric CO2 and/or reducing the amount of solar radiation that arrives or remains on Earth. The research described here suggests that the use of cover crops could contribute to both efforts. Agricultural land covered in vegetation generally reflects more light than does bare soil, increasing what is known as albedo (i.e., the fraction of solar radiation reflected by a surface). Furthermore, because cover crops develop for months and are then ploughed under (i.e., serving as green fertiliser), they also promote carbon sequestration in the soil.

Using satellite data from all over Europe, researchers modeled the effects of changes in albedo resulting from the introduction of cover crops in agricultural fields. They only considered areas in which climatic conditions and crop rotations were favourable to cover crop use. The results suggest that cover crops could be added to approximately 4.2% of the land surface in Europe for at least 3 months each year. Furthermore, cover crops could significantly increase the albedo of most agricultural fields, except in areas where soils are already very light-coloured, such as in the Marne region or certain parts of Spain.

Overall, this study suggests that the introduction of cover crops could mitigate approximately 7% of the annual greenhouse gas emissions from Europe's agricultural and forestry sector (using 2011 emissions as a reference) by simultaneously increasing albedo, reducing the need for fertiliser, and increasing carbon sequestration. The albedo effect accounts for 10 to 13% of this total effect. If this mitigation approach were to be implemented, its contribution could increase even further given that soils would get darker because of the carbon being stored in the form of organic matter. The European countries for whom this technique holds the most promise are France, Bulgaria, Romania, and Germany (in order of relevance). It remains to be determined how viable this approach is compared to other climate engineering techniques, given possible climatic and ecological feedback, economic constraints, and ethical concerns. A significant advantage of this method is that it can be put into place progressively and reversed at any moment.

Press Relations:
Dominique Carrer (the publication's first author) (33 5 61 07 94 77)


Dominique Carrer, Gaétan Pique, Morgan Ferlicoq, Xavier Ceamanos and Eric Ceschia. What is the potential of cropland albedo management in the fight against global warming? A case study based on the use of cover crops. Environ. Res. Lett. in press https://doi.org/10.1088/1748-9326/aab650