Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point
The hard snowball Earth bifurcation point is determined by the level of atmospheric carbon dioxide concentration (pCO(2)) below which complete glaciation of the planet would occur. In previous studies, the bifurcation point was determined based on the assumption that the extent of continental glacia...
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CLIMATE DYNAMICS
2017
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Online Access: | https://hdl.handle.net/20.500.11897/473142 https://doi.org/10.1007/s00382-016-3278-1 |
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ftpekinguniv:oai:localhost:20.500.11897/473142 2023-05-15T16:40:11+02:00 Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point Liu, Yonggang Peltier, W. Richard Yang, Jun Vettoretti, Guido Wang, Yuwei Liu, YG (reprint author), Peking Univ, Sch Phys, Dept Atmospher & Ocean Sci, Beijing 100871, Peoples R China. Peking Univ, Sch Phys, Dept Atmospher & Ocean Sci, Beijing 100871, Peoples R China. Univ Toronto, Dept Phys, 60 St George St, Toronto, ON M5S 1A7, Canada. 2017 https://hdl.handle.net/20.500.11897/473142 https://doi.org/10.1007/s00382-016-3278-1 en eng CLIMATE DYNAMICS CLIMATE DYNAMICS.2017,48(11),3459-3474. 1907358 0930-7575 http://hdl.handle.net/20.500.11897/473142 1432-0894 doi:10.1007/s00382-016-3278-1 WOS:000402122200001 SCI Snowball Earth Bifurcation point Tropical ice sheet Atmospheric heat transport Neoproterozoic MODERN SOFT SNOWBALL CLIMATE INITIATION MODEL SIMULATIONS GLACIATIONS IMPACT HYPOTHESIS LUMINOSITY DYNAMICS Journal 2017 ftpekinguniv https://doi.org/20.500.11897/473142 https://doi.org/10.1007/s00382-016-3278-1 2021-08-01T11:12:43Z The hard snowball Earth bifurcation point is determined by the level of atmospheric carbon dioxide concentration (pCO(2)) below which complete glaciation of the planet would occur. In previous studies, the bifurcation point was determined based on the assumption that the extent of continental glaciation could be neglected and the results thereby obtained suggested that very low values of pCO(2) would be required (similar to 100 ppmv). Here, we deduce the upper bound on the bifurcation point using the coupled atmosphere-ocean climate model of the NCAR that is referred to as the Community Climate System Model version 3 by assuming that the continents are fully covered by ice sheets prior to executing the transition into the hard snowball state. The thickness of the ice sheet is assumed to be that obtained by an ice-sheet model coupled to an energy balance model for a soft snowball Earth. We find that the hard snowball Earth bifurcation point is in the ranges of 600-630 and 300-320 ppmv for the 720 and 570 Ma continental configurations, respectively. These critical points are between 10 and 3 times higher than their respective values when ice sheets are completely neglected. We also find that when the ice sheets are thinner than those assumed above, the climate is colder and the bifurcation point is larger. The key process that causes the excess cooling when continental ice sheets are thin is shown to be associated with the fact that atmospheric heat transport from the adjacent oceans to the ice sheet-covered continents is enhanced in such conditions. Feedbacks from sea-ice expansion and reduced water vapor concentration further cool the oceanic regions strongly. Ministry of Education of China; NSERC [A9627] SCI(E) ARTICLE 11 3459-3474 48 Journal/Newspaper Ice Sheet Sea ice Peking University Institutional Repository (PKU IR) Climate Dynamics 48 11-12 3459 3474 |
institution |
Open Polar |
collection |
Peking University Institutional Repository (PKU IR) |
op_collection_id |
ftpekinguniv |
language |
English |
topic |
Snowball Earth Bifurcation point Tropical ice sheet Atmospheric heat transport Neoproterozoic MODERN SOFT SNOWBALL CLIMATE INITIATION MODEL SIMULATIONS GLACIATIONS IMPACT HYPOTHESIS LUMINOSITY DYNAMICS |
spellingShingle |
Snowball Earth Bifurcation point Tropical ice sheet Atmospheric heat transport Neoproterozoic MODERN SOFT SNOWBALL CLIMATE INITIATION MODEL SIMULATIONS GLACIATIONS IMPACT HYPOTHESIS LUMINOSITY DYNAMICS Liu, Yonggang Peltier, W. Richard Yang, Jun Vettoretti, Guido Wang, Yuwei Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
topic_facet |
Snowball Earth Bifurcation point Tropical ice sheet Atmospheric heat transport Neoproterozoic MODERN SOFT SNOWBALL CLIMATE INITIATION MODEL SIMULATIONS GLACIATIONS IMPACT HYPOTHESIS LUMINOSITY DYNAMICS |
description |
The hard snowball Earth bifurcation point is determined by the level of atmospheric carbon dioxide concentration (pCO(2)) below which complete glaciation of the planet would occur. In previous studies, the bifurcation point was determined based on the assumption that the extent of continental glaciation could be neglected and the results thereby obtained suggested that very low values of pCO(2) would be required (similar to 100 ppmv). Here, we deduce the upper bound on the bifurcation point using the coupled atmosphere-ocean climate model of the NCAR that is referred to as the Community Climate System Model version 3 by assuming that the continents are fully covered by ice sheets prior to executing the transition into the hard snowball state. The thickness of the ice sheet is assumed to be that obtained by an ice-sheet model coupled to an energy balance model for a soft snowball Earth. We find that the hard snowball Earth bifurcation point is in the ranges of 600-630 and 300-320 ppmv for the 720 and 570 Ma continental configurations, respectively. These critical points are between 10 and 3 times higher than their respective values when ice sheets are completely neglected. We also find that when the ice sheets are thinner than those assumed above, the climate is colder and the bifurcation point is larger. The key process that causes the excess cooling when continental ice sheets are thin is shown to be associated with the fact that atmospheric heat transport from the adjacent oceans to the ice sheet-covered continents is enhanced in such conditions. Feedbacks from sea-ice expansion and reduced water vapor concentration further cool the oceanic regions strongly. Ministry of Education of China; NSERC [A9627] SCI(E) ARTICLE 11 3459-3474 48 |
author2 |
Liu, YG (reprint author), Peking Univ, Sch Phys, Dept Atmospher & Ocean Sci, Beijing 100871, Peoples R China. Peking Univ, Sch Phys, Dept Atmospher & Ocean Sci, Beijing 100871, Peoples R China. Univ Toronto, Dept Phys, 60 St George St, Toronto, ON M5S 1A7, Canada. |
format |
Journal/Newspaper |
author |
Liu, Yonggang Peltier, W. Richard Yang, Jun Vettoretti, Guido Wang, Yuwei |
author_facet |
Liu, Yonggang Peltier, W. Richard Yang, Jun Vettoretti, Guido Wang, Yuwei |
author_sort |
Liu, Yonggang |
title |
Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
title_short |
Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
title_full |
Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
title_fullStr |
Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
title_full_unstemmed |
Strong effects of tropical ice-sheet coverage and thickness on the hard snowball Earth bifurcation point |
title_sort |
strong effects of tropical ice-sheet coverage and thickness on the hard snowball earth bifurcation point |
publisher |
CLIMATE DYNAMICS |
publishDate |
2017 |
url |
https://hdl.handle.net/20.500.11897/473142 https://doi.org/10.1007/s00382-016-3278-1 |
genre |
Ice Sheet Sea ice |
genre_facet |
Ice Sheet Sea ice |
op_source |
SCI |
op_relation |
CLIMATE DYNAMICS.2017,48(11),3459-3474. 1907358 0930-7575 http://hdl.handle.net/20.500.11897/473142 1432-0894 doi:10.1007/s00382-016-3278-1 WOS:000402122200001 |
op_doi |
https://doi.org/20.500.11897/473142 https://doi.org/10.1007/s00382-016-3278-1 |
container_title |
Climate Dynamics |
container_volume |
48 |
container_issue |
11-12 |
container_start_page |
3459 |
op_container_end_page |
3474 |
_version_ |
1766030558611111936 |