Carbon budgets for 1.5 and 2°C targets lowered by natural wetland and permafrost feedbacks

Comyn-Platt, Edward; Hayman, Garry ORCID: https://orcid.org/0000-0003-3825-4156; Huntingford, Chris ORCID: https://orcid.org/0000-0002-5941-7770; Chadburn, Sarah E.; Burke, Eleanor J.; Harper, Anna B.; Collins, William J.; Webber, Christopher P.; Powell, Tom; Cox, Peter M.; Gedney, Nicola; Sitch, Stephen. 2018 Carbon budgets for 1.5 and 2°C targets lowered by natural wetland and permafrost feedbacks. Nature Geoscience, 11 (8). 568-573. https://doi.org/10.1038/s41561-018-0174-9

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Abstract/Summary

Global methane emissions from natural wetlands and carbon release from permafrost thaw have a positive feedback on climate, yet are not represented in most state-of-the-art climate models. Furthermore, a fraction of the thawed permafrost carbon is released as methane, enhancing the combined feedback strength. We present simulations with an inverted intermediate complexity climate model, which follows prescribed global warming pathways to stabilization at 1.5 or 2.0 °C above pre-industrial levels by the year 2100, and which incorporates a state-of-the-art global land surface model with updated descriptions of wetland and permafrost carbon release. We demonstrate that the climate feedbacks from those two processes are substantial. Specifically, permissible anthropogenic fossil fuel CO2 emission budgets are reduced by 17–23% (47–56 GtC) for stabilization at 1.5 °C, and 9–13% (52–57 GtC) for 2.0 °C stabilization. In our simulations these feedback processes respond more quickly at temperatures below 1.5 °C, and the differences between the 1.5 and 2 °C targets are disproportionately small. This key finding holds for transient emission pathways to 2100 and does not account for longer-term implications of these feedback processes. We conclude that natural feedback processes from wetlands and permafrost must be considered in assessments of transient emission pathways to limit global warming.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1038/s41561-018-0174-9
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	1752-0894
Additional Information. Not used in RCUK Gateway to Research.:	View-only full-text version available via publisher link (see Related URLs).
Additional Keywords:	carbon cycle, climate and Earth system modelling, climate-change mitigation
NORA Subject Terms:	Meteorology and Climatology
Related URLs:	Publisher
Date made live:	26 Jul 2018 15:57 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/520608

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