Natural Climate Solutions. What are the natural sinks, what capacity they offer, how they can be maximized?

Abstract

Better stewardship of land 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.

We map country-level mitigation potential for 10 priority types of NCS actions. From these maps we identify groups of countries, each with a similar set of dominant NCS opportunities. For some country groups, NCS opportunities are dominated by restoration actions in forests, agricultural lands, and/or wetlands. In others country groups, mitigation potential is dominated by conservation of existing forests, grasslands, and wetlands.

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.