The key role of forests in meeting climate targets requires science for credible mitigation

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Abstract

Forest-based climate mitigation may occur through conserving and enhancing the carbon sink and through reducing greenhouse gas emissions from deforestation. Yet the inclusion of forests in international climate agreements has been complex, often considered a secondary mitigation option. In the context of the Paris Climate Agreement, countries submitted their (Intended) Nationally Determined Contributions ((I)NDCs), including climate mitigation targets. Assuming full implementation of (I)NDCs, we show that land use, and forests in particular, emerge as a key component of the Paris Agreement: turning globally from a net anthropogenic source during 1990–2010 (1.3 ± 1.1 GtCO2e yr−1) to a net sink of carbon by 2030 (up to −1.1 ± 0.5 GtCO2e yr−1), and providing a quarter of emission reductions planned by countries. Realizing and tracking this mitigation potential requires more transparency in countries’ pledges and enhanced science-policy cooperation to increase confidence in numbers, including reconciling the 3 GtCO2e yr−1 difference in estimates between country reports and scientific studies.

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Figure 1: Global LULUCF net GHG flux for the historical period and future scenarios based on analyses of countries’ documents and mitigation pledges ((I)NDCs).
Figure 2: Comparison of historical LULUCF net GHG flux from this analysis and other key global LULUCF data sets.
Figure 3: Comparison of historical and projected land fluxes from this analysis (based on country reports, including conditional (I)NDCs) and IPCC AR5 (based on global models and the projections of the four Representative Concentration Pathways (RCP) scenarios).
Figure 4: Contribution of mitigation in the LULUCF sector to total GHG mitigation across all sectors according to countries’ (I)NDCs.

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Acknowledgements

Author Jim Penman passed away recently. Jim Penman was the UK and EU negotiator on LULUCF for many years, coordinator of key IPCC methodological reports and credited as one of the key architects of the LULUCF process under the UNFCCC. He was awarded an OBE (Order of the British Empire) for his work. He was an outstanding scientist and negotiator, who strived always towards a better world.

Author information

G.G. conceived the analysis on (I)NDCs, executed the calculations and drafted the paper. J.H., F.D., M.d.E. and J.P. contributed to the analysis and to the writing of the paper. S.F. provided data from FAO FRA 2015 and contributed to the analysis. J.H. was supported by the Leverhulme Foundation and EU FP7 through project LUC4C (GA603542).

Correspondence to Giacomo Grassi.

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The authors declare no competing financial interests.

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Grassi, G., House, J., Dentener, F. et al. The key role of forests in meeting climate targets requires science for credible mitigation. Nature Clim Change 7, 220–226 (2017) doi:10.1038/nclimate3227

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