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Natural climate solutions

  1. Joseph Fargionea
  1. aThe Nature Conservancy, Arlington, VA 22203;
  2. bDepartment of Biology, James Madison University, Harrisonburg, VA 22807;
  3. cWoods Hole Research Center, Falmouth, MA 02540;
  4. dDepartment of Agricultural, Environmental, and Development Economics, The Ohio State University, Columbus, OH 43210;
  5. eCary Institute of Ecosystem Studies, Millbrook, NY 12545;
  6. fTerraCarbon LLC, Charlottesville, VA 22903;
  7. gResources for the Future, Washington, DC 20036;
  8. hInstitute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, Scotland, United Kingdom;
  9. iCollege of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853-1901;
  10. jMinistry of Agriculture, Government of Brazil, Brasilia 70000, Brazil;
  11. kNatural Resource Ecology Laboratory & Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO 80523-1499;
  12. lWorld Resources Institute, Washington, DC 20002;
  13. mCommonwealth Scientific and Industrial Research Organization, St. Lucia, QLD 4067, Australia;
  14. nDepartment of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Ume?, Sweden;
  15. oDepartment of Applied Economics, University of Minnesota, Saint Paul, MN 55108;
  16. pDepartment of Geographical Sciences, University of Maryland, College Park, MD 20742;
  17. qDepartment of Biology, University of Florida, Gainesville, FL 32611-8526;
  18. rWetlands International, 6700 AL Wageningen, The Netherlands;
  19. sGund Institute for the Environment, University of Vermont, Burlington, VT 05405
  1. Contributed by William H. Schlesinger, September 5, 2017 (sent for review June 26, 2017; reviewed by Jason Funk and Will R. Turner)

Significance

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.

Footnotes

  • ?1To whom correspondence may be addressed. Email: bgriscom{at}tnc.org or schlesingerw{at}caryinstitute.org.
  • Author contributions: B.W.G., J.A., P.W.E., R.A.H., G.L., D.A.M., W.H.S., D.S., J.V.S., P.S., P.W., C.Z., A.B., J.C., R.T.C., C.D., M.R.H., J.K., E.L., S.P., F.E.P., J.S., M.S., E.W., and J. Fargione designed research; B.W.G., P.W.E., R.A.H., G.L., D.A.M., W.H.S., D.S., J.V.S., P.W., C.Z., R.T.C., P.E., J.K., E.L., and J. Fargione performed research; L.L., S.M., and P.P. contributed new reagents/analytic tools; B.W.G., P.W.E., R.A.H., G.L., D.A.M., D.S., J.V.S., P.W., C.Z., T.G., M.H., S.M.L., and J. Fargione analyzed data; and B.W.G., J.A., P.W.E., G.L., D.A.M., W.H.S, D.S., P.S., P.W., C.Z., S.M.L., and J. Fargione wrote the paper.

  • Reviewers: J. Funk, Center for Carbon Removal; and W.R.T., Conservation International.

  • The authors declare no conflict of interest.

  • Data deposition: A global spatial dataset of reforestation opportunities has been deposited on Zenodo (http://www.danielhellerman.com/record/883444).

  • This article contains supporting information online at www.danielhellerman.com/lookup/suppl/doi:10.1073/pnas.1710465114/-/DCSupplemental.

This is an open access article distributed under the PNAS license.

Online Impact

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