Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution
During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable...
Main Authors: | , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
AMER GEOPHYSICAL UNION
2010
|
Subjects: | |
Online Access: | https://discovery.ucl.ac.uk/id/eprint/1324186/1/2009PA001809.pdf https://discovery.ucl.ac.uk/id/eprint/1324186/ |
id |
ftucl:oai:eprints.ucl.ac.uk.OAI2:1324186 |
---|---|
record_format |
openpolar |
spelling |
ftucl:oai:eprints.ucl.ac.uk.OAI2:1324186 2023-12-24T10:17:39+01:00 Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution Brierley, CM Fedorov, AV 2010-06-23 application/pdf https://discovery.ucl.ac.uk/id/eprint/1324186/1/2009PA001809.pdf https://discovery.ucl.ac.uk/id/eprint/1324186/ eng eng AMER GEOPHYSICAL UNION https://discovery.ucl.ac.uk/id/eprint/1324186/1/2009PA001809.pdf https://discovery.ucl.ac.uk/id/eprint/1324186/ open Paleoceanography , 25 , Article PA2214. (2010) Permanent El-Nino Northern-hemisphere glaciation Tropical Pacific Warm pool Circulation Atmosphere Ma Monsoon Middle Epoch Article 2010 ftucl 2023-11-27T13:07:36Z During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable to the modern about 2 Myr ago (as estimated on the eastern side of the Pacific). The zonal SST gradient along the equator, virtually nonexistent in the early Pliocene, reached modern values between 1 and 2 Myr ago. Here, we use an atmospheric general circulation model to investigate the relative roles of the changes in the meridional and zonal temperature gradients for the onset of glacial cycles and for Pliocene-Pleistocene climate evolution in general. We show that the increase in the meridional SST gradient reduces air temperature and increases snowfall over most of North America, both factors favorable to ice sheet inception. The impacts of changes in the zonal gradient, while also important over North America, are somewhat weaker than those caused by meridional temperature variations. The establishment of the modern meridional and zonal SST distributions leads to roughly 3.2 degrees C and 0.6 degrees C decreases in global mean temperature, respectively. Changes in the two gradients also have large regional consequences, including aridification of Africa (both gradients) and strengthening of the Indian monsoon (zonal gradient). Ultimately, this study suggests that the growth of Northern Hemisphere ice sheets is a result of the global cooling of Earth's climate since 4 Myr rather than its initial cause. Thus, reproducing the correct changes in the SST distribution is critical for a model to simulate the transition from the warm early Pliocene to a colder Pleistocene climate. Article in Journal/Newspaper Ice Sheet University College London: UCL Discovery Pacific Indian |
institution |
Open Polar |
collection |
University College London: UCL Discovery |
op_collection_id |
ftucl |
language |
English |
topic |
Permanent El-Nino Northern-hemisphere glaciation Tropical Pacific Warm pool Circulation Atmosphere Ma Monsoon Middle Epoch |
spellingShingle |
Permanent El-Nino Northern-hemisphere glaciation Tropical Pacific Warm pool Circulation Atmosphere Ma Monsoon Middle Epoch Brierley, CM Fedorov, AV Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
topic_facet |
Permanent El-Nino Northern-hemisphere glaciation Tropical Pacific Warm pool Circulation Atmosphere Ma Monsoon Middle Epoch |
description |
During the early Pliocene (roughly 4 Myr ago), the ocean warm water pool extended over most of the tropics. Subsequently, the warm pool gradually contracted toward the equator, while midlatitudes and subpolar regions cooled, establishing a meridional sea surface temperature (SST) gradient comparable to the modern about 2 Myr ago (as estimated on the eastern side of the Pacific). The zonal SST gradient along the equator, virtually nonexistent in the early Pliocene, reached modern values between 1 and 2 Myr ago. Here, we use an atmospheric general circulation model to investigate the relative roles of the changes in the meridional and zonal temperature gradients for the onset of glacial cycles and for Pliocene-Pleistocene climate evolution in general. We show that the increase in the meridional SST gradient reduces air temperature and increases snowfall over most of North America, both factors favorable to ice sheet inception. The impacts of changes in the zonal gradient, while also important over North America, are somewhat weaker than those caused by meridional temperature variations. The establishment of the modern meridional and zonal SST distributions leads to roughly 3.2 degrees C and 0.6 degrees C decreases in global mean temperature, respectively. Changes in the two gradients also have large regional consequences, including aridification of Africa (both gradients) and strengthening of the Indian monsoon (zonal gradient). Ultimately, this study suggests that the growth of Northern Hemisphere ice sheets is a result of the global cooling of Earth's climate since 4 Myr rather than its initial cause. Thus, reproducing the correct changes in the SST distribution is critical for a model to simulate the transition from the warm early Pliocene to a colder Pleistocene climate. |
format |
Article in Journal/Newspaper |
author |
Brierley, CM Fedorov, AV |
author_facet |
Brierley, CM Fedorov, AV |
author_sort |
Brierley, CM |
title |
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
title_short |
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
title_full |
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
title_fullStr |
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
title_full_unstemmed |
Relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and Pliocene-Pleistocene climate evolution |
title_sort |
relative importance of meridional and zonal sea surface temperature gradients for the onset of the ice ages and pliocene-pleistocene climate evolution |
publisher |
AMER GEOPHYSICAL UNION |
publishDate |
2010 |
url |
https://discovery.ucl.ac.uk/id/eprint/1324186/1/2009PA001809.pdf https://discovery.ucl.ac.uk/id/eprint/1324186/ |
geographic |
Pacific Indian |
geographic_facet |
Pacific Indian |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Paleoceanography , 25 , Article PA2214. (2010) |
op_relation |
https://discovery.ucl.ac.uk/id/eprint/1324186/1/2009PA001809.pdf https://discovery.ucl.ac.uk/id/eprint/1324186/ |
op_rights |
open |
_version_ |
1786205905459609600 |