Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Natural climate solutions can provide up to 37% of emissions reductions needed by 2030

Leave a Comment

Bronson Griscom et al. Natural Climate Solutions. PNAS (Proceedings of the Ntional Academy of Sciences, US). October 17 2018 doi: 10.1073/pnas.1710465114

Most nations recently agreed to hold global average temperature rise to well below 2 °C. We examine how much climate mitigation nature can contribute to this goal with a comprehensive analysis of “natural climate solutions” (NCS): 20 conservation, restoration, and/or improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We show that NCS can provide over one-third of the cost-effective climate mitigation needed between now and 2030 to stabilize warming to below 2 °C. Alongside aggressive fossil fuel emissions reductions, NCS offer a powerful set of options for nations to deliver on the Paris Climate Agreement while improving soil productivity, cleaning our air and water, and maintaining biodiversity.

Abstract: Better stewardship of land is needed to achieve the Paris Climate Agreement goal of holding warming to 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 petagrams of CO2 equivalent (PgCO2e) y−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 y−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 to 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.

From the text:

Our assessment of the potential contribution of NCS to meeting the Paris Agreement is conservative in three ways. First, payments for ecosystem services other than carbon sequestration are not considered here and could spur cost-effective implementation of NCS beyond the levels we identified. Natural climate solutions enhance biodiversity habitat, water filtration, flood control, air filtration, and soil quality (Fig. 1) among other services, some of which have high monetary values (3436) (see SI Appendix, Table S5 for details). Improved human health from dietary shifts toward plant-based foods reduce healthcare expenses and further offset NCS costs (37).

Second, our findings are conservative because we only include activities and greenhouse gas fluxes where data were sufficiently robust for global extrapolation. For example, we exclude no-till agriculture (Conservation Agriculture pathway), we exclude improved manure management in concentrated animal feed operations (Nutrient Management pathway), we exclude adaptive multipaddock grazing (Grazing pathways), and we exclude soil carbon emissions that may occur with conversion of forests to pasture (Avoided Forest Conversion pathway). Future research may reveal a robust empirical basis for including such activities and fluxes within these pathways.

Third, the Paris Agreement states goals of limiting warming to “well below 2 °C” and pursuing “efforts to limit the temperature increase to 1.5 °C.” Our analysis specifies a >66% chance of holding warming to just below 2 °C (30). Additional investment in all mitigation efforts (i.e., beyond ∼100 USD MgCO2−1), including NCS, would be warranted to keep warming to well below 2 °C, or to 1.5 °C, particularly if a very likely (90%) chance of success is desired.

Read TNC’s post on this publication: Nature’s Make or Break Potential for Climate Change

…Forest loss accounts for 8 to 10 percent of carbon emissions globally; tropical rainforests ….work as massive carbon sinks and are home to many of the world’s indigenous people and endangered species.  But other global ecosystems and managed lands—from farmlands and peatlands to seagrass and tidal marshes—have garnered less attention from climate regulators, both as a source of emissions and a potential mitigation solution….,%2020%20Pathways.png

View all articles

Comments are closed