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A probabilistic calibration of climate sensitivity and terrestrial carbon change in GENIE-1

A probabilistic calibration of climate sensitivity and terrestrial carbon change in GENIE-1
A probabilistic calibration of climate sensitivity and terrestrial carbon change in GENIE-1
In order to investigate Last Glacial Maximum and future climate, we “precalibrate” the intermediate complexity model GENIE-1 by applying a rejection sampling approach to deterministic emulations of the model. We develop ~1,000 parameter sets which reproduce the main features of modern climate, but not precise observations. This allows a wide range of large-scale feedback response strengths which generally encompass the range of GCM behaviour. We build a deterministic emulator of climate sensitivity and quantify the contributions of atmospheric (±0.93°C, 1?) vegetation (±0.32°C), ocean (±0.24°C) and sea–ice (±0.14°C) parameterisations to the total uncertainty. We then perform an LGM-constrained Bayesian calibration, incorporating data-driven priors and formally accounting for structural error. We estimate climate sensitivity as likely (66% confidence) to lie in the range 2.6–4.4°C, with a peak probability at 3.6°C. We estimate LGM cooling likely to lie in the range 5.3–7.5°C, with a peak probability at 6.2°C. In addition to estimates of global temperature change, we apply our ensembles to derive LGM and 2xCO2 probability distributions for land carbon storage, Atlantic overturning and sea–ice coverage. Notably, under 2xCO2 we calculate a probability of 37% that equilibrium terrestrial carbon storage is reduced from modern values, so the land sink has become a net source of atmospheric CO2.
0930-7575
785-806
Holden, Philip B.
007e7f65-7cba-4117-bea8-bcd2caa38459
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Oliver, K.I.C.
588b11c6-4d0c-4c59-94e2-255688474987
Lenton, T.M.
f2b4fe3d-ef5e-4c85-9677-bfc20c266b65
Wilkinson, R.D.
ec0684d7-ce95-43c0-94e0-ae5783487ad7
Holden, Philip B.
007e7f65-7cba-4117-bea8-bcd2caa38459
Edwards, N.R.
e41b719b-784e-4748-acc4-6ccbc4643c7d
Oliver, K.I.C.
588b11c6-4d0c-4c59-94e2-255688474987
Lenton, T.M.
f2b4fe3d-ef5e-4c85-9677-bfc20c266b65
Wilkinson, R.D.
ec0684d7-ce95-43c0-94e0-ae5783487ad7

Holden, Philip B., Edwards, N.R., Oliver, K.I.C., Lenton, T.M. and Wilkinson, R.D. (2010) A probabilistic calibration of climate sensitivity and terrestrial carbon change in GENIE-1. Climate Dynamics, 35 (5), 785-806. (doi:10.1007/s00382-009-0630-8).

Record type: Article

Abstract

In order to investigate Last Glacial Maximum and future climate, we “precalibrate” the intermediate complexity model GENIE-1 by applying a rejection sampling approach to deterministic emulations of the model. We develop ~1,000 parameter sets which reproduce the main features of modern climate, but not precise observations. This allows a wide range of large-scale feedback response strengths which generally encompass the range of GCM behaviour. We build a deterministic emulator of climate sensitivity and quantify the contributions of atmospheric (±0.93°C, 1?) vegetation (±0.32°C), ocean (±0.24°C) and sea–ice (±0.14°C) parameterisations to the total uncertainty. We then perform an LGM-constrained Bayesian calibration, incorporating data-driven priors and formally accounting for structural error. We estimate climate sensitivity as likely (66% confidence) to lie in the range 2.6–4.4°C, with a peak probability at 3.6°C. We estimate LGM cooling likely to lie in the range 5.3–7.5°C, with a peak probability at 6.2°C. In addition to estimates of global temperature change, we apply our ensembles to derive LGM and 2xCO2 probability distributions for land carbon storage, Atlantic overturning and sea–ice coverage. Notably, under 2xCO2 we calculate a probability of 37% that equilibrium terrestrial carbon storage is reduced from modern values, so the land sink has become a net source of atmospheric CO2.

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Published date: 2010
Organisations: Ocean and Earth Science

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Local EPrints ID: 68801
URI: http://eprints.soton.ac.uk/id/eprint/68801
ISSN: 0930-7575
PURE UUID: d5df8228-63da-49dd-babe-6415de1f3ea6

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Date deposited: 05 Oct 2009
Last modified: 13 Mar 2024 19:07

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Contributors

Author: Philip B. Holden
Author: N.R. Edwards
Author: K.I.C. Oliver
Author: T.M. Lenton
Author: R.D. Wilkinson

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