Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model
Although the origins of the 40,000-year glacial cycles during the early Pleistocene are readily attributed to changes in Earth's obliquity (also having a 40,000-year period), the lack of ice-volume variability at precession periods (20,000 years) is difficult to reconcile with most parameteriza...
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American Geophysical Union
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ftharvardudash:oai:dash.harvard.edu:1/4686802 2023-05-15T16:40:29+02:00 Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model Huybers, Peter John Tziperman, Eli 2008 application/pdf http://nrs.harvard.edu/urn-3:HUL.InstRepos:4686802 https://doi.org/10.1029/2007PA001463 en_US eng American Geophysical Union http://dx.doi.org/10.1029/2007PA001463 Paleoceanography Huybers, Peter J., and Eli Tziperman. 2008. Integrated summer insolation controls 40,000-year glacial cycles in an ice-sheet/energy-balance model. Paleoceanography 23(PA1208): 1-18. 0883-8305 http://nrs.harvard.edu/urn-3:HUL.InstRepos:4686802 doi:10.1029/2007PA001463 Journal Article 2008 ftharvardudash https://doi.org/10.1029/2007PA001463 2022-04-04T12:36:29Z Although the origins of the 40,000-year glacial cycles during the early Pleistocene are readily attributed to changes in Earth's obliquity (also having a 40,000-year period), the lack of ice-volume variability at precession periods (20,000 years) is difficult to reconcile with most parameterizations of the insolation forcing. It was recently proposed that precession's influence on glaciation is muted because variations in the intensity of summer insolation are counterbalanced by changes in the duration of the summertime, but no climate model has yet been shown to generate obliquity period glacial cycles in response to the seasonal insolation forcing. Here we present a coupled ice-sheet/energy-balance model that reproduces the seasonal cycle and, when run over long time periods, generates glacial variability in response to changes in Earth's orbital configuration. The model is forced by the full seasonal cycle in insolation, and its response can be understood within the context of the integrated summer insolation forcing. The simple fact that obliquity's period is roughly twice as long as that of precession results in a larger amplitude glacial response to obliquity. However, for the model to generate almost exclusively obliquity period glacial variability, two other conditions must be met. First, the ice sheet's ablation zone must reside poleward of ∼60°N because insolation intensity is more sensitive to changes in Earth's obliquity at high latitudes. Second, the ablation season must be long enough for precession's opposing influences on summer and fall insolation intensity to counterbalance one another. These conditions are consistent with a warm climate and a thin ice sheet, where the latter is simulated as a response to subglacial sediment deformation. If a colder climate is prescribed, or in the absence of basal motion, ice sheets tend to be larger and undergo greater precession period variability, in keeping with proxy observations of late Pleistocene glaciation. Earth and Planetary Sciences Version of Record Article in Journal/Newspaper Ice Sheet Harvard University: DASH - Digital Access to Scholarship at Harvard Paleoceanography 23 1 n/a n/a |
institution |
Open Polar |
collection |
Harvard University: DASH - Digital Access to Scholarship at Harvard |
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ftharvardudash |
language |
English |
description |
Although the origins of the 40,000-year glacial cycles during the early Pleistocene are readily attributed to changes in Earth's obliquity (also having a 40,000-year period), the lack of ice-volume variability at precession periods (20,000 years) is difficult to reconcile with most parameterizations of the insolation forcing. It was recently proposed that precession's influence on glaciation is muted because variations in the intensity of summer insolation are counterbalanced by changes in the duration of the summertime, but no climate model has yet been shown to generate obliquity period glacial cycles in response to the seasonal insolation forcing. Here we present a coupled ice-sheet/energy-balance model that reproduces the seasonal cycle and, when run over long time periods, generates glacial variability in response to changes in Earth's orbital configuration. The model is forced by the full seasonal cycle in insolation, and its response can be understood within the context of the integrated summer insolation forcing. The simple fact that obliquity's period is roughly twice as long as that of precession results in a larger amplitude glacial response to obliquity. However, for the model to generate almost exclusively obliquity period glacial variability, two other conditions must be met. First, the ice sheet's ablation zone must reside poleward of ∼60°N because insolation intensity is more sensitive to changes in Earth's obliquity at high latitudes. Second, the ablation season must be long enough for precession's opposing influences on summer and fall insolation intensity to counterbalance one another. These conditions are consistent with a warm climate and a thin ice sheet, where the latter is simulated as a response to subglacial sediment deformation. If a colder climate is prescribed, or in the absence of basal motion, ice sheets tend to be larger and undergo greater precession period variability, in keeping with proxy observations of late Pleistocene glaciation. Earth and Planetary Sciences Version of Record |
format |
Article in Journal/Newspaper |
author |
Huybers, Peter John Tziperman, Eli |
spellingShingle |
Huybers, Peter John Tziperman, Eli Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
author_facet |
Huybers, Peter John Tziperman, Eli |
author_sort |
Huybers, Peter John |
title |
Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
title_short |
Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
title_full |
Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
title_fullStr |
Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
title_full_unstemmed |
Integrated Summer Insolation Forcing and 40,000-Year Glacial Cycles: The Perspective from an Ice-Sheet/Energy-Balance Model |
title_sort |
integrated summer insolation forcing and 40,000-year glacial cycles: the perspective from an ice-sheet/energy-balance model |
publisher |
American Geophysical Union |
publishDate |
2008 |
url |
http://nrs.harvard.edu/urn-3:HUL.InstRepos:4686802 https://doi.org/10.1029/2007PA001463 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
http://dx.doi.org/10.1029/2007PA001463 Paleoceanography Huybers, Peter J., and Eli Tziperman. 2008. Integrated summer insolation controls 40,000-year glacial cycles in an ice-sheet/energy-balance model. Paleoceanography 23(PA1208): 1-18. 0883-8305 http://nrs.harvard.edu/urn-3:HUL.InstRepos:4686802 doi:10.1029/2007PA001463 |
op_doi |
https://doi.org/10.1029/2007PA001463 |
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Paleoceanography |
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23 |
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1 |
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1766030892896092160 |