Does a difference in ice sheets between Marine Isotope Stages 3 and 5a affect the duration of stadials? Implications from hosing experiments
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Published:2021-09-28
Issue:5
Volume:17
Page:1919-1936
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ISSN:1814-9332
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Container-title:Climate of the Past
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language:en
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Short-container-title:Clim. Past
Author:
Sherriff-Tadano SamORCID, Abe-Ouchi AyakoORCID, Oka Akira, Mitsui TakahitoORCID, Saito FuyukiORCID
Abstract
Abstract. Glacial periods undergo frequent climate shifts between warm
interstadials and cold stadials on a millennial timescale. Recent studies
show that the duration of these climate modes varies with the background
climate; a colder background climate and lower CO2 generally result in a shorter interstadial and a longer stadial through its impact on the
Atlantic Meridional Overturning Circulation (AMOC). However, the duration of
stadials is shorter during Marine Isotope Stage 3 (MIS3) than during MIS5, despite
the colder climate in MIS3, suggesting potential control from other climate
factors on the duration of stadials. In this study, we investigate the role
of glacial ice sheets. For this purpose, freshwater hosing experiments are
conducted with an atmosphere–ocean general circulation model under MIS5a
and MIS3 boundary conditions, as well as MIS3 boundary conditions with MIS5a
ice sheets. The impact of ice sheet differences on the duration of the
stadials is evaluated by comparing recovery times of the AMOC after the
freshwater forcing is stopped. These experiments show a slightly shorter
recovery time of the AMOC during MIS3 compared with MIS5a, which is
consistent with ice core data. We find that larger glacial ice sheets in
MIS3 shorten the recovery time. Sensitivity experiments show that stronger
surface winds over the North Atlantic shorten the recovery time by
increasing the surface salinity and decreasing the sea ice amount in the
deepwater formation region, which sets favorable conditions for oceanic
convection. In contrast, we also find that surface cooling by larger ice
sheets tends to increase the recovery time of the AMOC by increasing the sea ice thickness over the deepwater formation region. Thus, this study suggests that the larger ice sheet during MIS3 compared with MIS5a could have contributed to the shortening of stadials in MIS3, despite the climate being colder than that of MIS5a, because surface wind plays a larger role.
Funder
Japan Society for the Promotion of Science Volkswagen Foundation
Publisher
Copernicus GmbH
Subject
Paleontology,Stratigraphy,Global and Planetary Change
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