Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing
International audience During the Last Glacial Maximum, tropical sea surface temperatures were 1 to 3 degrees C cooler than present(1-4), but the altitude of the snowlines of tropical glaciers(5,6) was lower than would be expected in light of these sea surface temperatures. Indeed, both glacial and...
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Online Access: | https://hal.science/hal-01458299 https://hal.science/hal-01458299/document https://hal.science/hal-01458299/file/39048.pdf https://doi.org/10.1038/NGEO2082 |
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ftinraparis:oai:HAL:hal-01458299v1 2024-09-15T18:31:05+00:00 Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing Tripati, Aradhna K. Sahany, Sandeep Pittman, Dustin Eagle, Robert A. Neelin, J. David Mitchell, Jonathan L. Beaufort, Luc, L Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) 2014-03 https://hal.science/hal-01458299 https://hal.science/hal-01458299/document https://hal.science/hal-01458299/file/39048.pdf https://doi.org/10.1038/NGEO2082 en eng HAL CCSD Nature Publishing Group info:eu-repo/semantics/altIdentifier/doi/10.1038/NGEO2082 hal-01458299 https://hal.science/hal-01458299 https://hal.science/hal-01458299/document https://hal.science/hal-01458299/file/39048.pdf doi:10.1038/NGEO2082 info:eu-repo/semantics/OpenAccess ISSN: 1752-0894 Nature Geoscience https://hal.science/hal-01458299 Nature Geoscience, 2014, 7 (3), pp.205-209. ⟨10.1038/NGEO2082⟩ [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2014 ftinraparis https://doi.org/10.1038/NGEO2082 2024-08-13T14:11:12Z International audience During the Last Glacial Maximum, tropical sea surface temperatures were 1 to 3 degrees C cooler than present(1-4), but the altitude of the snowlines of tropical glaciers(5,6) was lower than would be expected in light of these sea surface temperatures. Indeed, both glacial and twentieth-century snowlines seem to require lapse rates that are steeper than a moist adiabat(7,8). Here we use estimates of Last Glacial Maximum sea surface temperature in the Indo-Pacific warm pool based on the clumped isotope palaeotemperature proxy in planktonic foraminifera and coccoliths, along with radiative-convective calculations of vertical atmospheric thermal structure, to assess the controls on tropical glacier snowlines. Using extensive new data sets for the region, we demonstrate that mean environmental lapse rates are steeper than moist adiabatic during the recent and glacial. We reconstruct glacial sea surface temperatures 4 to 5 degrees C cooler than modern. We include modern and glacial sea surface temperatures in calculations of atmospheric convection that account for mixing between rising air and ambient air, and derive tropical glacier snowlines with altitudes consistent with twentieth-century and Last Glacial Maximum reconstructions. Sea surface temperature changes <= 3 degrees C are excluded unless glacial relative humidity values were outside the range associated with deep convection in the modern. We conclude that the entrainment of ambient air into rising air masses significantly alters the vertical temperature structure of the troposphere in modern and ancient regions of deep convection. Furthermore, if all glacial tropical temperatures were cooler than previously estimated, it would imply a higher equilibrium climate sensitivity than included in present models(9,10). Article in Journal/Newspaper Planktonic foraminifera Institut National de la Recherche Agronomique: ProdINRA Nature Geoscience 7 3 205 209 |
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Open Polar |
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Institut National de la Recherche Agronomique: ProdINRA |
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ftinraparis |
language |
English |
topic |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
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[SDU.STU]Sciences of the Universe [physics]/Earth Sciences Tripati, Aradhna K. Sahany, Sandeep Pittman, Dustin Eagle, Robert A. Neelin, J. David Mitchell, Jonathan L. Beaufort, Luc, L Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
topic_facet |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience During the Last Glacial Maximum, tropical sea surface temperatures were 1 to 3 degrees C cooler than present(1-4), but the altitude of the snowlines of tropical glaciers(5,6) was lower than would be expected in light of these sea surface temperatures. Indeed, both glacial and twentieth-century snowlines seem to require lapse rates that are steeper than a moist adiabat(7,8). Here we use estimates of Last Glacial Maximum sea surface temperature in the Indo-Pacific warm pool based on the clumped isotope palaeotemperature proxy in planktonic foraminifera and coccoliths, along with radiative-convective calculations of vertical atmospheric thermal structure, to assess the controls on tropical glacier snowlines. Using extensive new data sets for the region, we demonstrate that mean environmental lapse rates are steeper than moist adiabatic during the recent and glacial. We reconstruct glacial sea surface temperatures 4 to 5 degrees C cooler than modern. We include modern and glacial sea surface temperatures in calculations of atmospheric convection that account for mixing between rising air and ambient air, and derive tropical glacier snowlines with altitudes consistent with twentieth-century and Last Glacial Maximum reconstructions. Sea surface temperature changes <= 3 degrees C are excluded unless glacial relative humidity values were outside the range associated with deep convection in the modern. We conclude that the entrainment of ambient air into rising air masses significantly alters the vertical temperature structure of the troposphere in modern and ancient regions of deep convection. Furthermore, if all glacial tropical temperatures were cooler than previously estimated, it would imply a higher equilibrium climate sensitivity than included in present models(9,10). |
author2 |
Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Tripati, Aradhna K. Sahany, Sandeep Pittman, Dustin Eagle, Robert A. Neelin, J. David Mitchell, Jonathan L. Beaufort, Luc, L |
author_facet |
Tripati, Aradhna K. Sahany, Sandeep Pittman, Dustin Eagle, Robert A. Neelin, J. David Mitchell, Jonathan L. Beaufort, Luc, L |
author_sort |
Tripati, Aradhna K. |
title |
Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
title_short |
Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
title_full |
Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
title_fullStr |
Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
title_full_unstemmed |
Modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
title_sort |
modern and glacial tropical snowlines controlled by sea surface temperature and atmospheric mixing |
publisher |
HAL CCSD |
publishDate |
2014 |
url |
https://hal.science/hal-01458299 https://hal.science/hal-01458299/document https://hal.science/hal-01458299/file/39048.pdf https://doi.org/10.1038/NGEO2082 |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
ISSN: 1752-0894 Nature Geoscience https://hal.science/hal-01458299 Nature Geoscience, 2014, 7 (3), pp.205-209. ⟨10.1038/NGEO2082⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1038/NGEO2082 hal-01458299 https://hal.science/hal-01458299 https://hal.science/hal-01458299/document https://hal.science/hal-01458299/file/39048.pdf doi:10.1038/NGEO2082 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1038/NGEO2082 |
container_title |
Nature Geoscience |
container_volume |
7 |
container_issue |
3 |
container_start_page |
205 |
op_container_end_page |
209 |
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1810472691754336256 |