Constraints and enablers for increasing carbon storage in the terrestrial biosphere

Harnessing nature-based climate solutions (NbCS) to help simultaneously achieve climate and conservation goals is an attractive win-win. The contribution of NbCS to climate action relies on both biogeochemical potential and the ability to overcome environmental, economic and governance constraints for implementation. As such, estimates of additional NbCS-related terrestrial biosphere storage potential range from less than 100 GtCO2 to more than 800 GtCO2. In this Review, we assess the negative emissions contributions of NbCS — including reforestation, improved forest management and soil carbon sequestration — alongside their environmental, social and governance constraints. Given near-term implementation challenges and long-term biogeochemical constraints, a reasonable value for the expected impact of NbCS is up to 100–200 GtCO2 in negative emissions for the remainder of the twenty-first century. To sustainably reach this level, focus should be on projects with clear co-benefits, and must not come at the expense of a reduction in emissions from deforestation and forest degradation, rapid decarbonization and innovation from alternative negative emissions technologies. Nature-based climate solutions can help meet climate mitigation goals, but estimates of their carbon storage potential vary. This Review discusses the constraints and potential contributions of increasing carbon storage in the terrestrial biosphere, suggesting a conservative estimate of 100–200 GtCO2 in negative emissions to 2100.