Ice-driven CO 2 feedback on ice volume
The origin of the major ice-sheet variations during the last 2.7 million years is a long-standing mystery. Neither the dominant 41 000-year cycles in δ 18 O/ice-volume during the late Pliocene and early Pleistocene nor the late-Pleistocene oscillations near 100 000 years is a linear ('Milankovi...
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ftdoajarticles:oai:doaj.org/article:213857acf20e433ca1796eba5afbe0d4 2023-05-15T16:40:30+02:00 Ice-driven CO 2 feedback on ice volume W. F. Ruddiman 2006-01-01T00:00:00Z https://doaj.org/article/213857acf20e433ca1796eba5afbe0d4 EN eng Copernicus Publications http://www.clim-past.net/2/43/2006/cp-2-43-2006.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/213857acf20e433ca1796eba5afbe0d4 Climate of the Past, Vol 2, Iss 1, Pp 43-55 (2006) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2006 ftdoajarticles 2022-12-31T02:51:19Z The origin of the major ice-sheet variations during the last 2.7 million years is a long-standing mystery. Neither the dominant 41 000-year cycles in δ 18 O/ice-volume during the late Pliocene and early Pleistocene nor the late-Pleistocene oscillations near 100 000 years is a linear ('Milankovitch') response to summer insolation forcing. Both responses must result from non-linear behavior within the climate system. Greenhouse gases (primarily CO 2 ) are a plausible source of the required non-linearity, but confusion has persisted over whether the gases force ice volume or are a positive feedback. During the last several hundred thousand years, CO 2 and ice volume (marine δ 18 O) have varied in phase at the 41 000-year obliquity cycle and nearly in phase within the ~100 000-year band. This timing rules out greenhouse-gas forcing of a very slow ice response and instead favors ice control of a fast CO 2 response. In the schematic model proposed here, ice sheets responded linearly to insolation forcing at the precession and obliquity cycles prior to 0.9 million years ago, but CO 2 feedback amplified the ice response at the 41 000-year period by a factor of approximately two. After 0.9 million years ago, with slow polar cooling, ablation weakened. CO 2 feedback continued to amplify ice-sheet growth every 41 000 years, but weaker ablation permitted some ice to survive insolation maxima of low intensity. Step-wise growth of these longer-lived ice sheets continued until peaks in northern summer insolation produced abrupt deglaciations every ~85 000 to ~115 000 years. Most of the deglacial ice melting resulted from the same CO 2 /temperature feedback that had built the ice sheets. Several processes have the northern geographic origin, as well as the requisite orbital tempo and phasing, to be candidate mechanisms for ice-sheet control of CO 2 and their own feedback. Article in Journal/Newspaper Ice Sheet Directory of Open Access Journals: DOAJ Articles |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 W. F. Ruddiman Ice-driven CO 2 feedback on ice volume |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
The origin of the major ice-sheet variations during the last 2.7 million years is a long-standing mystery. Neither the dominant 41 000-year cycles in δ 18 O/ice-volume during the late Pliocene and early Pleistocene nor the late-Pleistocene oscillations near 100 000 years is a linear ('Milankovitch') response to summer insolation forcing. Both responses must result from non-linear behavior within the climate system. Greenhouse gases (primarily CO 2 ) are a plausible source of the required non-linearity, but confusion has persisted over whether the gases force ice volume or are a positive feedback. During the last several hundred thousand years, CO 2 and ice volume (marine δ 18 O) have varied in phase at the 41 000-year obliquity cycle and nearly in phase within the ~100 000-year band. This timing rules out greenhouse-gas forcing of a very slow ice response and instead favors ice control of a fast CO 2 response. In the schematic model proposed here, ice sheets responded linearly to insolation forcing at the precession and obliquity cycles prior to 0.9 million years ago, but CO 2 feedback amplified the ice response at the 41 000-year period by a factor of approximately two. After 0.9 million years ago, with slow polar cooling, ablation weakened. CO 2 feedback continued to amplify ice-sheet growth every 41 000 years, but weaker ablation permitted some ice to survive insolation maxima of low intensity. Step-wise growth of these longer-lived ice sheets continued until peaks in northern summer insolation produced abrupt deglaciations every ~85 000 to ~115 000 years. Most of the deglacial ice melting resulted from the same CO 2 /temperature feedback that had built the ice sheets. Several processes have the northern geographic origin, as well as the requisite orbital tempo and phasing, to be candidate mechanisms for ice-sheet control of CO 2 and their own feedback. |
format |
Article in Journal/Newspaper |
author |
W. F. Ruddiman |
author_facet |
W. F. Ruddiman |
author_sort |
W. F. Ruddiman |
title |
Ice-driven CO 2 feedback on ice volume |
title_short |
Ice-driven CO 2 feedback on ice volume |
title_full |
Ice-driven CO 2 feedback on ice volume |
title_fullStr |
Ice-driven CO 2 feedback on ice volume |
title_full_unstemmed |
Ice-driven CO 2 feedback on ice volume |
title_sort |
ice-driven co 2 feedback on ice volume |
publisher |
Copernicus Publications |
publishDate |
2006 |
url |
https://doaj.org/article/213857acf20e433ca1796eba5afbe0d4 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Climate of the Past, Vol 2, Iss 1, Pp 43-55 (2006) |
op_relation |
http://www.clim-past.net/2/43/2006/cp-2-43-2006.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/213857acf20e433ca1796eba5afbe0d4 |
_version_ |
1766030894506704896 |