Soil carbon sequestration for carbon dioxide removal – a systematic review

Globally, soil contain twice as much carbon as the atmosphere and twice that in trees and other vegetation. Soils have become depleted in carbon through land use change and management, meaning that there is potential in these managed soils to increase carbon stocks. Previous studies have suggested that soil carbon sequestration has a large, cost-competitive mitigation potential. Nevertheless, limitations of soil C sequestration include time-limitation, non-permanence, displacement and difficulties in verification. Despite these limitations, soil C sequestration can be useful to meet short term to medium-term targets, and confers a number of co-benefits on soils, making it a viable option for reducing the short-term atmospheric CO2 concentration, thus buying time to develop longer term emission reduction solutions across all sectors of the economy.

As part of an ecosystem of CDR reviews reported in other presentations at this conference, we performed a systematic review and meta-analysis of papers on soil carbon sequestration, examining costs, potentials, co-benefits and side-effects. An initial search identified over 15,000 papers which were screened for relevance, leaving and smaller number of papers describing land management changes which increase the soil organic carbon content, resulting in a net removal of CO2 from the atmosphere, for detailed review and data extraction. We present the outcomes of this systematic review, compare the range of co-benefits and side-effects associated with soil carbon sequestration to other CDR options, and discuss what this means for using soil carbon sequestration for CDR.