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Pathways to 1.5 and 2 °C warming based on observational and geological constraints

Pathways to 1.5 and 2 °C warming based on observational and geological constraints
Pathways to 1.5 and 2 °C warming based on observational and geological constraints
To restrict global warming to below the agreed targets requires limiting carbon emissions, the principal driver of anthropogenic warming. However, there is significant uncertainty in projecting the amount of carbon that can be emitted, in part due to the limited number of Earth system model simulations and their discrepancies with present-day observations. Here we demonstrate a novel approach to reduce the uncertainty of climate projections; using theory and geological evidence we generate a very large ensemble (3 × 104) of projections that closely match records for nine key climate metrics, which include warming and ocean heat content. Our analysis narrows the uncertainty in surface-warming projections and reduces the range in equilibrium climate sensitivity. We find that a warming target of 1.5 °C above the pre-industrial level requires the total emitted carbon from the start of year 2017 to be less than 195–205 PgC (in over 66% of the simulations), whereas a warming target of 2 °C is only likely if the emitted carbon remains less than 395–455 PgC. At the current emission rates, these warming targets are reached in 17–18 years and 35–41 years, respectively, so that there is a limited window to develop a more carbon-efficient future.
1752-0894
102–107
Goodwin, Philip
87dbb154-5c39-473a-8121-c794487ee1fd
Katavouta, Anna
022df79a-fae4-45b4-be7d-6c67576e744c
Roussenov, Vassil M.
f1ad06e6-abdf-4ace-951e-3c9216ae282b
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Williams, Richard G.
4fa8f460-9b71-4058-9b54-89bd916b5f43
Goodwin, Philip
87dbb154-5c39-473a-8121-c794487ee1fd
Katavouta, Anna
022df79a-fae4-45b4-be7d-6c67576e744c
Roussenov, Vassil M.
f1ad06e6-abdf-4ace-951e-3c9216ae282b
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Williams, Richard G.
4fa8f460-9b71-4058-9b54-89bd916b5f43

Goodwin, Philip, Katavouta, Anna, Roussenov, Vassil M., Foster, Gavin L., Rohling, Eelco J. and Williams, Richard G. (2018) Pathways to 1.5 and 2 °C warming based on observational and geological constraints Nature Geoscience, 11, 102–107. (doi:10.1038/s41561-017-0054-8).

Record type: Article

Abstract

To restrict global warming to below the agreed targets requires limiting carbon emissions, the principal driver of anthropogenic warming. However, there is significant uncertainty in projecting the amount of carbon that can be emitted, in part due to the limited number of Earth system model simulations and their discrepancies with present-day observations. Here we demonstrate a novel approach to reduce the uncertainty of climate projections; using theory and geological evidence we generate a very large ensemble (3 × 104) of projections that closely match records for nine key climate metrics, which include warming and ocean heat content. Our analysis narrows the uncertainty in surface-warming projections and reduces the range in equilibrium climate sensitivity. We find that a warming target of 1.5 °C above the pre-industrial level requires the total emitted carbon from the start of year 2017 to be less than 195–205 PgC (in over 66% of the simulations), whereas a warming target of 2 °C is only likely if the emitted carbon remains less than 395–455 PgC. At the current emission rates, these warming targets are reached in 17–18 years and 35–41 years, respectively, so that there is a limited window to develop a more carbon-efficient future.

Text Goodwin_etal_AuthorAcceptedManuscript - Accepted Manuscript
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More information

Accepted/In Press date: 15 December 2017
e-pub ahead of print date: 22 January 2018
Published date: 2018

Identifiers

Local EPrints ID: 417178
URI: https://eprints.soton.ac.uk/id/eprint/417178
ISSN: 1752-0894
PURE UUID: c5b9fbd5-181e-43dc-8a2b-ad82c58c1961
ORCID for Eelco J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

Catalogue record

Date deposited: 23 Jan 2018 17:30
Last modified: 05 Feb 2018 17:30

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