On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle
Climate over the past million years has been dominated by glaciation cycles with periods near 23,000, 41,000, and 100,000 years. In a linear version of the Milankovitch theory, the two shorter cycles can be explained as responses to insolation cycles driven by precession and obliquity. But the 100,0...
Published in: | Paleoceanography |
---|---|
Main Authors: | , , , , , , , , , , , , , , , , , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Amer Geophysical Union
1993
|
Subjects: | |
Online Access: | http://hdl.handle.net/2078.1/49227 https://doi.org/10.1029/93PA02751 |
id |
ftunivlouvain:oai:dial.uclouvain.be:boreal:49227 |
---|---|
record_format |
openpolar |
spelling |
ftunivlouvain:oai:dial.uclouvain.be:boreal:49227 2024-05-12T08:05:25+00:00 On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle Imbrie, J. Berger, André Boyle, EA. Clemens, SC. Duffy, A. Howard, WR. Kukla, G. Kutzbach, J. Martinson, DG. Mcintyre, A. Mix, AC. Molfino, B. Morley, JJ. Peterson, LC. Pisias, NG. Prell, WL. Raymo, ME. Shackleton, NJ. Toggweiler, JR. UCL - SC/PHYS - Département de physique 1993 http://hdl.handle.net/2078.1/49227 https://doi.org/10.1029/93PA02751 eng eng Amer Geophysical Union boreal:49227 http://hdl.handle.net/2078.1/49227 doi:10.1029/93PA02751 urn:ISSN:0883-8305 urn:EISSN:1944-9186 Paleoceanography, Vol. 8, no. 6, p. 699-735 (1993) info:eu-repo/semantics/article 1993 ftunivlouvain https://doi.org/10.1029/93PA02751 2024-04-17T17:30:35Z Climate over the past million years has been dominated by glaciation cycles with periods near 23,000, 41,000, and 100,000 years. In a linear version of the Milankovitch theory, the two shorter cycles can be explained as responses to insolation cycles driven by precession and obliquity. But the 100,000-year radiation cycle (arising from eccentricity variation) is much too small in amplitude and too late in phase to produce the corresponding climate cycle by direct forcing. We present phase observations showing that the geographic progression of local responses over the 100,000-year cycle is similar to the progression in the other two cycles, implying that a similar set of internal climatic mechanisms operates in all three. But the phase sequence in the 100,000-year cycle requires a source of climatic inertia having a time constant (similar to 15,000 years) much larger than the other cycles (similar to 5,000 years). Our conceptual model identifies massive northern hemisphere ice sheets as this larger inertial source. When these ice sheets, forced by precession and obliquity, exceed a critical size, they cease responding as linear Milankovitch slaves and drive atmospheric and oceanic responses that mimic the externally forced responses. In our model, the coupled system acts as a nonlinear amplifier that is particularly sensitive to eccentricity-driven modulations in the 23,000-year sea level cycle. During an interval when sea level is forced upward from a major low stand by a Milankovitch response acting either alone or in combination with an internally driven, higher-frequency process, ice sheets grounded on continental shelves become unstable, mass wasting accelerates, and the resulting deglaciation sets the phase of one wave in the train of 100,000-year oscillations. Whether a glacier or ice sheet influences the climate depends very much on the scale.The interesting aspect is that an effect on the local climate can still make an ice mass grow larger and larger, thereby gradually increasing its radius of ... Article in Journal/Newspaper Ice Sheet DIAL@UCLouvain (Université catholique de Louvain) Paleoceanography 8 6 699 735 |
institution |
Open Polar |
collection |
DIAL@UCLouvain (Université catholique de Louvain) |
op_collection_id |
ftunivlouvain |
language |
English |
description |
Climate over the past million years has been dominated by glaciation cycles with periods near 23,000, 41,000, and 100,000 years. In a linear version of the Milankovitch theory, the two shorter cycles can be explained as responses to insolation cycles driven by precession and obliquity. But the 100,000-year radiation cycle (arising from eccentricity variation) is much too small in amplitude and too late in phase to produce the corresponding climate cycle by direct forcing. We present phase observations showing that the geographic progression of local responses over the 100,000-year cycle is similar to the progression in the other two cycles, implying that a similar set of internal climatic mechanisms operates in all three. But the phase sequence in the 100,000-year cycle requires a source of climatic inertia having a time constant (similar to 15,000 years) much larger than the other cycles (similar to 5,000 years). Our conceptual model identifies massive northern hemisphere ice sheets as this larger inertial source. When these ice sheets, forced by precession and obliquity, exceed a critical size, they cease responding as linear Milankovitch slaves and drive atmospheric and oceanic responses that mimic the externally forced responses. In our model, the coupled system acts as a nonlinear amplifier that is particularly sensitive to eccentricity-driven modulations in the 23,000-year sea level cycle. During an interval when sea level is forced upward from a major low stand by a Milankovitch response acting either alone or in combination with an internally driven, higher-frequency process, ice sheets grounded on continental shelves become unstable, mass wasting accelerates, and the resulting deglaciation sets the phase of one wave in the train of 100,000-year oscillations. Whether a glacier or ice sheet influences the climate depends very much on the scale.The interesting aspect is that an effect on the local climate can still make an ice mass grow larger and larger, thereby gradually increasing its radius of ... |
author2 |
UCL - SC/PHYS - Département de physique |
format |
Article in Journal/Newspaper |
author |
Imbrie, J. Berger, André Boyle, EA. Clemens, SC. Duffy, A. Howard, WR. Kukla, G. Kutzbach, J. Martinson, DG. Mcintyre, A. Mix, AC. Molfino, B. Morley, JJ. Peterson, LC. Pisias, NG. Prell, WL. Raymo, ME. Shackleton, NJ. Toggweiler, JR. |
spellingShingle |
Imbrie, J. Berger, André Boyle, EA. Clemens, SC. Duffy, A. Howard, WR. Kukla, G. Kutzbach, J. Martinson, DG. Mcintyre, A. Mix, AC. Molfino, B. Morley, JJ. Peterson, LC. Pisias, NG. Prell, WL. Raymo, ME. Shackleton, NJ. Toggweiler, JR. On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
author_facet |
Imbrie, J. Berger, André Boyle, EA. Clemens, SC. Duffy, A. Howard, WR. Kukla, G. Kutzbach, J. Martinson, DG. Mcintyre, A. Mix, AC. Molfino, B. Morley, JJ. Peterson, LC. Pisias, NG. Prell, WL. Raymo, ME. Shackleton, NJ. Toggweiler, JR. |
author_sort |
Imbrie, J. |
title |
On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
title_short |
On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
title_full |
On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
title_fullStr |
On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
title_full_unstemmed |
On the Structure and Origin of Major Glaciation Cycles .2. the 100,000-year Cycle |
title_sort |
on the structure and origin of major glaciation cycles .2. the 100,000-year cycle |
publisher |
Amer Geophysical Union |
publishDate |
1993 |
url |
http://hdl.handle.net/2078.1/49227 https://doi.org/10.1029/93PA02751 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Paleoceanography, Vol. 8, no. 6, p. 699-735 (1993) |
op_relation |
boreal:49227 http://hdl.handle.net/2078.1/49227 doi:10.1029/93PA02751 urn:ISSN:0883-8305 urn:EISSN:1944-9186 |
op_doi |
https://doi.org/10.1029/93PA02751 |
container_title |
Paleoceanography |
container_volume |
8 |
container_issue |
6 |
container_start_page |
699 |
op_container_end_page |
735 |
_version_ |
1798847709753376768 |