Climatic Changes of the Last 18,000 Years: Observations and Model Simulations
Changes in solar radiation arising from changes in the orientation of the earth's axis had pronounced effects on tropical monsoons and mid-latitude climates as well as on ice-sheet configuration during the last 18,000 years. COHMAP (Cooperative Holocene Mapping Project) has assembled a global a...
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1988
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Online Access: | http://dx.doi.org/10.1126/science.241.4869.1043 https://www.science.org/doi/pdf/10.1126/science.241.4869.1043 |
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craaas:10.1126/science.241.4869.1043 2024-10-13T14:08:06+00:00 Climatic Changes of the Last 18,000 Years: Observations and Model Simulations 1988 http://dx.doi.org/10.1126/science.241.4869.1043 https://www.science.org/doi/pdf/10.1126/science.241.4869.1043 en eng American Association for the Advancement of Science (AAAS) Science volume 241, issue 4869, page 1043-1052 ISSN 0036-8075 1095-9203 journal-article 1988 craaas https://doi.org/10.1126/science.241.4869.1043 2024-09-27T04:00:53Z Changes in solar radiation arising from changes in the orientation of the earth's axis had pronounced effects on tropical monsoons and mid-latitude climates as well as on ice-sheet configuration during the last 18,000 years. COHMAP (Cooperative Holocene Mapping Project) has assembled a global array of well-dated paleoclimatic data and used general-circulation models to identify and evaluate causes and mechanisms of climatic change. For the northern tropics, particularly in Africa and Asia, data and model results show that the orbitally induced increase in solar radiation in summer 12,000 to 6,000 years ago enhanced the thermal contrast between land and sea and thus produced strong summer monsoons, which raised lake levels in regions that are arid today. In middle to high latitudes the climatic response to both the insolation changes and to the retreating ice sheets led to readjustments in the vegetation in both the Northern and Southern hemispheres. Model results show that the large North American ice sheet split the westerly jet stream into northern and southern branches over North America. An increase in storms associated with the southern branch helps explain high lake levels and increased woodlands in the southwestern United States during full-glacial conditions. Comparisons of paleoclimatic data with the model simulations are important because models provide a theoretical framework for evaluating mechanisms of climatic change, and such comparisons help to evaluate the potential of general circulation models for predicting future climates. Article in Journal/Newspaper Ice Sheet AAAS Resource Center (American Association for the Advancement of Science) High Lake ENVELOPE(-110.849,-110.849,67.386,67.386) Science 241 4869 1043 1052 |
institution |
Open Polar |
collection |
AAAS Resource Center (American Association for the Advancement of Science) |
op_collection_id |
craaas |
language |
English |
description |
Changes in solar radiation arising from changes in the orientation of the earth's axis had pronounced effects on tropical monsoons and mid-latitude climates as well as on ice-sheet configuration during the last 18,000 years. COHMAP (Cooperative Holocene Mapping Project) has assembled a global array of well-dated paleoclimatic data and used general-circulation models to identify and evaluate causes and mechanisms of climatic change. For the northern tropics, particularly in Africa and Asia, data and model results show that the orbitally induced increase in solar radiation in summer 12,000 to 6,000 years ago enhanced the thermal contrast between land and sea and thus produced strong summer monsoons, which raised lake levels in regions that are arid today. In middle to high latitudes the climatic response to both the insolation changes and to the retreating ice sheets led to readjustments in the vegetation in both the Northern and Southern hemispheres. Model results show that the large North American ice sheet split the westerly jet stream into northern and southern branches over North America. An increase in storms associated with the southern branch helps explain high lake levels and increased woodlands in the southwestern United States during full-glacial conditions. Comparisons of paleoclimatic data with the model simulations are important because models provide a theoretical framework for evaluating mechanisms of climatic change, and such comparisons help to evaluate the potential of general circulation models for predicting future climates. |
format |
Article in Journal/Newspaper |
title |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
spellingShingle |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
title_short |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
title_full |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
title_fullStr |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
title_full_unstemmed |
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations |
title_sort |
climatic changes of the last 18,000 years: observations and model simulations |
publisher |
American Association for the Advancement of Science (AAAS) |
publishDate |
1988 |
url |
http://dx.doi.org/10.1126/science.241.4869.1043 https://www.science.org/doi/pdf/10.1126/science.241.4869.1043 |
long_lat |
ENVELOPE(-110.849,-110.849,67.386,67.386) |
geographic |
High Lake |
geographic_facet |
High Lake |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Science volume 241, issue 4869, page 1043-1052 ISSN 0036-8075 1095-9203 |
op_doi |
https://doi.org/10.1126/science.241.4869.1043 |
container_title |
Science |
container_volume |
241 |
container_issue |
4869 |
container_start_page |
1043 |
op_container_end_page |
1052 |
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1812814699458199552 |