Radical land use change coupled with enhanced carbon sequestration in productive agricultural lands has the potential to mitigate climate change, according to a new paper published in the journal Scientific Reports. However, if urban sprawl and the conversion from grassland and forest into cropland continue, agricultural soils could turn from a carbon sink to a significant source of carbon dioxide. Researchers from the University of Exeter, INRA and CERFACS in France and University of Leuven in Belgium warn that business-as-usual land use change is likely to lead to significant soil organic carbon loss due to the impact of climate change. This could endanger the functioning of soil’s vital ecosystem services such as food security, aquifer quality, soil erosion protection and flood regulation, the scientists say. “A reduction in anthropogenic CO2 levels is crucial to prevent further loss of carbon from our soils,” said lead author Dr Jeroen Meersmans from the University of Exeter. The researchers combined soil carbon models, land use and management data and different climate change scenarios, using France as a case study. They predict that land under almost all uses will be subject to dramatic losses of soil carbon by the end of the century. The study found that up to 25 percent of soil carbon in France could be lost to the atmosphere by 2100. According to Meersmans, an integrated strategy to protect soil functions and mitigate climate change would require the “promotion of land use changes and management that contribute to soil carbon sequestration”. One way to maintain soil’s important role as a carbon sink would be to convert cropland to grassland or forest. But the scientists say this is unrealistic because of the pressures on land resources imposed by urban expansion and food production. Therefore, the solution to enhanced carbon sequestration lies in productive agricultural lands. According to the study, by promoting or enforcing environment specific land and/or agro-management techniques, such as green manuring, reduced tillage, erosion prevention, smart irrigation, agroforestry and crop rotations at farm or landscape level, policy makers can attempt to counter that soils will act as very large sources of CO2 by the end of the century. “Purposive, targeted land use and agricultural practice changes would be needed if climate change mitigation is to be maximized,” says co-author Dr Dominique Arrouays of the French National Institute for Agricultural Research. “Therefore, the efforts to enhance carbon sequestration in soils, as proposed by France during the COP21, should be promoted immediately,” urges Arrouays. (ab)