The effect of greenhouse gas concentrations and ice sheets on the glacial AMOC in a coupled climate model.

Klockmann, Marlene, Mikolajewicz, Uwe and Marotzke, Jochem (2016) The effect of greenhouse gas concentrations and ice sheets on the glacial AMOC in a coupled climate model. Open Access Climate of the Past, 12 (9). pp. 1829-1846. DOI 10.5194/cp-12-1829-2016.

[img]
Preview
Text
cp-12-1829-2016.pdf - Published Version
Available under License Creative Commons: Attribution 4.0.

Download (3724Kb) | Preview

Supplementary data:

Abstract

Simulations with the Max Planck Institute Earth System Model (MPI-ESM) are used to study the sensitivity of the AMOC and the deep-ocean water masses during the Last Glacial Maximum to different sets of forcings. Analysing the individual contributions of the glacial forcings reveals that the ice sheets cause an increase in the overturning strength and a deepening of the North Atlantic Deep Water (NADW) cell, while the low greenhouse gas (GHG) concentrations cause a decrease in overturning strength and a shoaling of the NADW cell. The effect of the orbital configuration is negligible. The effects of the ice sheets and the GHG reduction balance each other in the deep ocean so that no shoaling of the NADW cell is simulated in the full glacial state. Experiments in which different GHG concentrations with linearly decreasing radiative forcing are applied to a setup with glacial ice sheets and orbital configuration show that GHG concentrations below the glacial level are necessary to cause a shoaling of the NADW cell with respect to the pre-industrial state in MPI-ESM. For a pCO2 of 149 ppm, the simulated overturning state and the deep-ocean water masses are in best agreement with the glacial state inferred from proxy data. Sensitivity studies confirm that brine release and shelf convection in the Southern Ocean are key processes for the shoaling of the NADW cell. Shoaling occurs only when Southern Ocean shelf water contributes significantly to the formation of Antarctic Bottom Water.

Document Type: Article
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/cp-12-1829-2016
ISSN: 1814-9324
Projects: PalMod in-kind
Date Deposited: 11 Sep 2018 12:39
Last Modified: 17 Jan 2019 13:18
URI: http://oceanrep.geomar.de/id/eprint/44231

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...