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Global and European climate impacts of a slowdown of the AMOC in a high resolution GCM

Global and European climate impacts of a slowdown of the AMOC in a high resolution GCM
Global and European climate impacts of a slowdown of the AMOC in a high resolution GCM
The impacts of a hypothetical slowdown in the Atlantic Meridional Overturning Circulation (AMOC) are assessed in a state-of-the-art global climate model (HadGEM3), with particular emphasis on Europe. This is the highest resolution coupled global climate model to be used to study the impacts of an AMOC slowdown so far. Many results found are consistent with previous studies and can be considered robust impacts from a large reduction or collapse of the AMOC. These include: widespread cooling throughout the North Atlantic and northern hemisphere in general; less precipitation in the northern hemisphere midlatitudes; large changes in precipitation in the tropics and a strengthening of the North Atlantic storm track. The focus on Europe, aided by the increase in resolution, has revealed previously undiscussed impacts, particularly those associated with changing atmospheric circulation patterns. Summer precipitation decreases (increases) in northern (southern) Europe and is associated with a negative summer North Atlantic Oscillation signal. Winter precipitation is also affected by the changing atmospheric circulation, with localised increases in precipitation associated with more winter storms and a strengthened winter storm track. Stronger westerly winds in winter increase the warming maritime effect while weaker westerlies in summer decrease the cooling maritime effect. In the absence of these circulation changes the cooling over Europe’s landmass would be even larger in both seasons. The general cooling and atmospheric circulation changes result in weaker peak river flows and vegetation productivity, which may raise issues of water availability and crop production.
Climate, Impacts, AMOC
0930-7575
3299-3316
Jackson, L.C.
d1c72916-2a89-47b8-89c8-137b63f404a6
Kahana, R.
c55df3a3-1b8f-4d79-b7f8-be6b58dd1a3f
Graham, T.
3c60e413-d4c6-4848-b1fa-b8fd0ca75740
Ringer, M.A.
d533f85c-d44b-4b9f-a48f-1ee79b8a7cf3
Woollings, T.
b6504fe8-0a99-4525-aa91-ab6f539a25ff
Mecking, J.V.
9b090069-5061-4340-b736-9690894ce203
Wood, R.A.
c135e2f0-fa83-4691-9c34-ac3d5de0c756
Jackson, L.C.
d1c72916-2a89-47b8-89c8-137b63f404a6
Kahana, R.
c55df3a3-1b8f-4d79-b7f8-be6b58dd1a3f
Graham, T.
3c60e413-d4c6-4848-b1fa-b8fd0ca75740
Ringer, M.A.
d533f85c-d44b-4b9f-a48f-1ee79b8a7cf3
Woollings, T.
b6504fe8-0a99-4525-aa91-ab6f539a25ff
Mecking, J.V.
9b090069-5061-4340-b736-9690894ce203
Wood, R.A.
c135e2f0-fa83-4691-9c34-ac3d5de0c756

Jackson, L.C., Kahana, R., Graham, T., Ringer, M.A., Woollings, T., Mecking, J.V. and Wood, R.A. (2015) Global and European climate impacts of a slowdown of the AMOC in a high resolution GCM. Climate Dynamics, 45 (11), 3299-3316. (doi:10.1007/s00382-015-2540-2).

Record type: Article

Abstract

The impacts of a hypothetical slowdown in the Atlantic Meridional Overturning Circulation (AMOC) are assessed in a state-of-the-art global climate model (HadGEM3), with particular emphasis on Europe. This is the highest resolution coupled global climate model to be used to study the impacts of an AMOC slowdown so far. Many results found are consistent with previous studies and can be considered robust impacts from a large reduction or collapse of the AMOC. These include: widespread cooling throughout the North Atlantic and northern hemisphere in general; less precipitation in the northern hemisphere midlatitudes; large changes in precipitation in the tropics and a strengthening of the North Atlantic storm track. The focus on Europe, aided by the increase in resolution, has revealed previously undiscussed impacts, particularly those associated with changing atmospheric circulation patterns. Summer precipitation decreases (increases) in northern (southern) Europe and is associated with a negative summer North Atlantic Oscillation signal. Winter precipitation is also affected by the changing atmospheric circulation, with localised increases in precipitation associated with more winter storms and a strengthened winter storm track. Stronger westerly winds in winter increase the warming maritime effect while weaker westerlies in summer decrease the cooling maritime effect. In the absence of these circulation changes the cooling over Europe’s landmass would be even larger in both seasons. The general cooling and atmospheric circulation changes result in weaker peak river flows and vegetation productivity, which may raise issues of water availability and crop production.

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More information

e-pub ahead of print date: March 2015
Published date: December 2015
Keywords: Climate, Impacts, AMOC
Organisations: Physical Oceanography

Identifiers

Local EPrints ID: 378192
URI: http://eprints.soton.ac.uk/id/eprint/378192
ISSN: 0930-7575
PURE UUID: 8316b099-364a-4c2d-99cc-3b7c09eac54d

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Date deposited: 19 Jun 2015 12:54
Last modified: 14 Mar 2024 20:19

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Contributors

Author: L.C. Jackson
Author: R. Kahana
Author: T. Graham
Author: M.A. Ringer
Author: T. Woollings
Author: J.V. Mecking
Author: R.A. Wood

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