Soil carbon debt of 12,000 years

Summary

Sanderman et al. (2017), published in PNAS, present a spatially explicit global estimate of the soil organic carbon debt accumulated over approximately 12,000 years of agricultural land use. Using a combination of global soil databases, land use history reconstructions, and modelling, the authors estimate that roughly 133 Pg of carbon has been lost from the top metre of soil due to farming and grazing. The study identifies croplands and heavily grazed regions as the largest contributors to this deficit, and frames soil carbon restoration as a meaningful, if partial, climate mitigation opportunity.

UK applicability

Although the study is global in scope, its findings are directly relevant to UK land use and climate policy, particularly in the context of soil carbon sequestration targets under the UK's net-zero commitments and initiatives such as the Sustainable Farming Incentive, where restoring soil organic matter in degraded arable and pastoral soils is an explicit policy aim.

Key measures

Soil organic carbon loss (Pg C); soil carbon debt by region and land use type; comparison of cultivated versus reference (potential natural vegetation) soil carbon stocks

Outcomes reported

The study estimated the cumulative loss of soil organic carbon resulting from agricultural land use since the onset of farming approximately 12,000 years ago, producing spatially explicit estimates of soil carbon debt across global biomes and land use types.

Topic tags