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Millennial timescale carbon cycle and climate change in an efficient Earth system model

Millennial timescale carbon cycle and climate change in an efficient Earth system model
Millennial timescale carbon cycle and climate change in an efficient Earth system model
A new Earth system model, GENIE-1, is presented which comprises a 3-D frictional geostrophic ocean, phosphate-restoring marine biogeochemistry, dynamic and thermodynamic sea-ice, land surface physics and carbon cycling, and a seasonal 2-D energy-moisture balance atmosphere. Three sets of model climate parameters are used to explore the robustness of the results and for traceability to earlier work. The model versions have climate sensitivity of 2.8–3.3°C and predict atmospheric CO2 close to present observations. Six idealized total fossil fuel CO2 emissions scenarios are used to explore a range of 1,100–15,000 GtC total emissions and the effect of rate of emissions. Atmospheric CO2 approaches equilibrium in year 3000 at 420–5,660 ppmv, giving 1.5–12.5°C global warming. The ocean is a robust carbon sink of up to 6.5 GtC year?1. Under ‘business as usual’, the land becomes a carbon source around year 2100 which peaks at up to 2.5 GtC year?1. Soil carbon is lost globally, boreal vegetation generally increases, whilst under extreme forcing, dieback of some tropical and sub-tropical vegetation occurs. Average ocean surface pH drops by up to 1.15 units. A Greenland ice sheet melt threshold of 2.6°C local warming is only briefly exceeded if total emissions are limited to 1,100 GtC, whilst 15,000 GtC emissions cause complete Greenland melt by year 3000, contributing 7 m to sea level rise. Total sea-level rise, including thermal expansion, is 0.4–10 m in year 3000 and ongoing. The Atlantic meridional overturning circulation shuts down in two out of three model versions, but only under extreme emissions including exotic fossil fuel resources.
0930-7575
687-711
Lenton, T.M.
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Williamson, M.S.
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Edwards, N.R.
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Marsh, R.
702c2e7e-ac19-4019-abd9-a8614ab27717
Price, A.R.
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Ridgwell, A.J.
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Shepherd, J.G.
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Cox, S.J.
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Lenton, T.M.
f2b4fe3d-ef5e-4c85-9677-bfc20c266b65
Williamson, M.S.
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Edwards, N.R.
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Marsh, R.
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Price, A.R.
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Ridgwell, A.J.
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Shepherd, J.G.
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Cox, S.J.
0e62aaed-24ad-4a74-b996-f606e40e5c55

Lenton, T.M., Williamson, M.S., Edwards, N.R., Marsh, R., Price, A.R., Ridgwell, A.J., Shepherd, J.G. and Cox, S.J. (2006) Millennial timescale carbon cycle and climate change in an efficient Earth system model. Climate Dynamics, 26 (7-8), 687-711. (doi:10.1007/s00382-006-0109-9).

Record type: Article

Abstract

A new Earth system model, GENIE-1, is presented which comprises a 3-D frictional geostrophic ocean, phosphate-restoring marine biogeochemistry, dynamic and thermodynamic sea-ice, land surface physics and carbon cycling, and a seasonal 2-D energy-moisture balance atmosphere. Three sets of model climate parameters are used to explore the robustness of the results and for traceability to earlier work. The model versions have climate sensitivity of 2.8–3.3°C and predict atmospheric CO2 close to present observations. Six idealized total fossil fuel CO2 emissions scenarios are used to explore a range of 1,100–15,000 GtC total emissions and the effect of rate of emissions. Atmospheric CO2 approaches equilibrium in year 3000 at 420–5,660 ppmv, giving 1.5–12.5°C global warming. The ocean is a robust carbon sink of up to 6.5 GtC year?1. Under ‘business as usual’, the land becomes a carbon source around year 2100 which peaks at up to 2.5 GtC year?1. Soil carbon is lost globally, boreal vegetation generally increases, whilst under extreme forcing, dieback of some tropical and sub-tropical vegetation occurs. Average ocean surface pH drops by up to 1.15 units. A Greenland ice sheet melt threshold of 2.6°C local warming is only briefly exceeded if total emissions are limited to 1,100 GtC, whilst 15,000 GtC emissions cause complete Greenland melt by year 3000, contributing 7 m to sea level rise. Total sea-level rise, including thermal expansion, is 0.4–10 m in year 3000 and ongoing. The Atlantic meridional overturning circulation shuts down in two out of three model versions, but only under extreme emissions including exotic fossil fuel resources.

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Published date: 2006

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Local EPrints ID: 26700
URI: http://eprints.soton.ac.uk/id/eprint/26700
ISSN: 0930-7575
PURE UUID: 62bb51f2-5d9e-435f-86eb-3604bc727228
ORCID for J.G. Shepherd: ORCID iD orcid.org/0000-0002-5230-4781

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Date deposited: 04 May 2006
Last modified: 16 Mar 2024 02:47

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Contributors

Author: T.M. Lenton
Author: M.S. Williamson
Author: N.R. Edwards
Author: R. Marsh
Author: A.R. Price
Author: A.J. Ridgwell
Author: J.G. Shepherd ORCID iD
Author: S.J. Cox

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