Ice-driven CO 2 feedback on ice volume
International audience 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 ? 18 O/ice-volume during the late Pliocene and early Pleistocene nor the late-Pleistocene oscillations near 100 000 years is a...
Main Author: | |
---|---|
Other Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2006
|
Subjects: | |
Online Access: | https://hal.science/hal-00298047 https://hal.science/hal-00298047/document https://hal.science/hal-00298047/file/cp-2-43-2006.pdf |
id |
ftccsdartic:oai:HAL:hal-00298047v1 |
---|---|
record_format |
openpolar |
spelling |
ftccsdartic:oai:HAL:hal-00298047v1 2023-11-12T04:18:44+01:00 Ice-driven CO 2 feedback on ice volume Ruddiman, W. F. Department of Environmental Sciences University of Virginia 2006-07-17 https://hal.science/hal-00298047 https://hal.science/hal-00298047/document https://hal.science/hal-00298047/file/cp-2-43-2006.pdf en eng HAL CCSD European Geosciences Union (EGU) hal-00298047 https://hal.science/hal-00298047 https://hal.science/hal-00298047/document https://hal.science/hal-00298047/file/cp-2-43-2006.pdf info:eu-repo/semantics/OpenAccess ISSN: 1814-9324 EISSN: 1814-9332 Climate of the Past https://hal.science/hal-00298047 Climate of the Past, 2006, 2 (1), pp.43-55 [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2006 ftccsdartic 2023-10-21T23:15:29Z International audience 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 ? 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 ? 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 Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Ruddiman, W. F. Ice-driven CO 2 feedback on ice volume |
topic_facet |
[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience 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 ? 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 ? 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. |
author2 |
Department of Environmental Sciences University of Virginia |
format |
Article in Journal/Newspaper |
author |
Ruddiman, W. F. |
author_facet |
Ruddiman, W. F. |
author_sort |
Ruddiman, W. F. |
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 |
HAL CCSD |
publishDate |
2006 |
url |
https://hal.science/hal-00298047 https://hal.science/hal-00298047/document https://hal.science/hal-00298047/file/cp-2-43-2006.pdf |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
ISSN: 1814-9324 EISSN: 1814-9332 Climate of the Past https://hal.science/hal-00298047 Climate of the Past, 2006, 2 (1), pp.43-55 |
op_relation |
hal-00298047 https://hal.science/hal-00298047 https://hal.science/hal-00298047/document https://hal.science/hal-00298047/file/cp-2-43-2006.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782335322264174592 |