Natural climate solutions

Better stewardship of land to is needed to achieve the Paris Climate Agreement goal of holding warming below 2°C; however, confusion persists about the specific set of land stewardship options available and their mitigation potential. To address this, we identify and quantify “natural climate solutions” (NCS): 20 conservation, restoration, and improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We find that the maximum potential of NCS – when constrained by food security, fiber security, and biodiversity conservation – is 23.8 PgCO2e yr-1 (95% CI 20.3 - 37.4). This is ≥30% higher than prior estimates, which did not include the full range of options and safeguards considered here. About half of this maximum (11.3 PgCO2e yr-1) represents cost effective climate mitigation, assuming the social cost of CO2 pollution is ≥100 USD MgCO2e -1 by 2030. Natural climate solutions can provide 37% of cost effective CO2 mitigation needed through 2030 for a >66% chance of holding warming below 2°C. One-third of this cost effective NCS mitigation can be delivered at or below 10 USD MgCO2 -1. Most NCS actions – if effectively implemented – also offer water filtration, flood buffering, soil health, biodiversity habitat, and enhanced climate resilience. Work remains to better constrain uncertainty of NCS mitigation estimates. Nevertheless, existing knowledge reported here provides a robust basis for immediate global action to improve ecosystem stewardship as a major solution to climate change.