The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes
Events surrounding Termination II, as preserved in the Vostok ice core, provide a number of clues about the mechanisms controlling glacial to interglacial climate change. Antarctic temperature and the atmosphere's CO2 content increased together over a period of ∼8000 years. This increase is bou...
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ftuloxford:oai:ora.ox.ac.uk:uuid:f0024980-7928-4c2b-bd20-1ef9e6880cc8 2023-05-15T13:37:40+02:00 The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes Broecker, W Henderson, G 2016-07-29 https://doi.org/10.1029/98PA00920 https://ora.ox.ac.uk/objects/uuid:f0024980-7928-4c2b-bd20-1ef9e6880cc8 eng eng doi:10.1029/98PA00920 https://ora.ox.ac.uk/objects/uuid:f0024980-7928-4c2b-bd20-1ef9e6880cc8 https://doi.org/10.1029/98PA00920 info:eu-repo/semantics/embargoedAccess Journal article 2016 ftuloxford https://doi.org/10.1029/98PA00920 2022-06-28T20:27:34Z Events surrounding Termination II, as preserved in the Vostok ice core, provide a number of clues about the mechanisms controlling glacial to interglacial climate change. Antarctic temperature and the atmosphere's CO2 content increased together over a period of ∼8000 years. This increase is bounded by a drop in dust flux at its onset and by a drop in the δ18O of trapped air at its finish. A similar lag between dust flux and foraminiferal δ18O is seen in a Southern Ocean marine record, suggesting that the δ18O in air trapped in Vostok ice is a valid proxy for ice volume. The synchronous change of atmospheric CO2 and southern hemisphere temperature thus preceded the melting of the northern hemisphere ice sheets. This observation, coupled with the fact that nutrient reorganization in the North Atlantic occurs with or after the sea level rise, eliminates many scenarios proposed to explain the CO2 rise, including those which rely on sea level change, conveyor-related nutrient redistribution, or North Atlantic cooling. Southern Ocean scenarios become the front runners, but the most popular mechanism, iron fertilization, has two problems in explaining the CO2 rise before Termination II. First, much of the dust demise occurs prior to the change in CO2, so if iron is the villain, a threshold value of its supply must be called upon above which productivity does not continue to increase. Second, the CO2 rise continues for some 4-5 kyr after the dust flux has fallen to close to zero. These problems may be solved if the increased iron supply in dust caused higher rates of nitrogen fixation during the glacial periods. In this case the residence time of oceanic nitrate of a few thousand years would enable decreasing productivity to be a global rather than a local phenomenon and would explain the slow rampup of atmospheric CO2. Article in Journal/Newspaper Antarc* Antarctic ice core North Atlantic Southern Ocean ORA - Oxford University Research Archive Antarctic Southern Ocean Paleoceanography 13 4 352 364 |
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Open Polar |
collection |
ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
Events surrounding Termination II, as preserved in the Vostok ice core, provide a number of clues about the mechanisms controlling glacial to interglacial climate change. Antarctic temperature and the atmosphere's CO2 content increased together over a period of ∼8000 years. This increase is bounded by a drop in dust flux at its onset and by a drop in the δ18O of trapped air at its finish. A similar lag between dust flux and foraminiferal δ18O is seen in a Southern Ocean marine record, suggesting that the δ18O in air trapped in Vostok ice is a valid proxy for ice volume. The synchronous change of atmospheric CO2 and southern hemisphere temperature thus preceded the melting of the northern hemisphere ice sheets. This observation, coupled with the fact that nutrient reorganization in the North Atlantic occurs with or after the sea level rise, eliminates many scenarios proposed to explain the CO2 rise, including those which rely on sea level change, conveyor-related nutrient redistribution, or North Atlantic cooling. Southern Ocean scenarios become the front runners, but the most popular mechanism, iron fertilization, has two problems in explaining the CO2 rise before Termination II. First, much of the dust demise occurs prior to the change in CO2, so if iron is the villain, a threshold value of its supply must be called upon above which productivity does not continue to increase. Second, the CO2 rise continues for some 4-5 kyr after the dust flux has fallen to close to zero. These problems may be solved if the increased iron supply in dust caused higher rates of nitrogen fixation during the glacial periods. In this case the residence time of oceanic nitrate of a few thousand years would enable decreasing productivity to be a global rather than a local phenomenon and would explain the slow rampup of atmospheric CO2. |
format |
Article in Journal/Newspaper |
author |
Broecker, W Henderson, G |
spellingShingle |
Broecker, W Henderson, G The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
author_facet |
Broecker, W Henderson, G |
author_sort |
Broecker, W |
title |
The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
title_short |
The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
title_full |
The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
title_fullStr |
The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
title_full_unstemmed |
The sequence of events surrounding Termination II and their implications for the cause of glacial-interglacial CO2 changes |
title_sort |
sequence of events surrounding termination ii and their implications for the cause of glacial-interglacial co2 changes |
publishDate |
2016 |
url |
https://doi.org/10.1029/98PA00920 https://ora.ox.ac.uk/objects/uuid:f0024980-7928-4c2b-bd20-1ef9e6880cc8 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic ice core North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic ice core North Atlantic Southern Ocean |
op_relation |
doi:10.1029/98PA00920 https://ora.ox.ac.uk/objects/uuid:f0024980-7928-4c2b-bd20-1ef9e6880cc8 https://doi.org/10.1029/98PA00920 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1029/98PA00920 |
container_title |
Paleoceanography |
container_volume |
13 |
container_issue |
4 |
container_start_page |
352 |
op_container_end_page |
364 |
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1766095734821617664 |