A Theory of Global Climate Change on Millennial Time Scales
A Theory of Global Climate Change on Millennial Time Scales In the northern hemisphere, large and rapid shifts in environmental conditions have occurred repeatedly over the last glacial- interglacial cycle. Indications are that climate change occurs on two characteristic time scales, roughly 1 - 3,0...
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DigitalCommons@UMaine
2001
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| Online Access: | https://digitalcommons.library.umaine.edu/orsp_reports/201 https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1213&context=orsp_reports |
| Summary: | A Theory of Global Climate Change on Millennial Time Scales In the northern hemisphere, large and rapid shifts in environmental conditions have occurred repeatedly over the last glacial- interglacial cycle. Indications are that climate change occurs on two characteristic time scales, roughly 1 - 3,000 years and 5 - 10,000 years. Evidence for millennial-scale climate variability has been found in ice cores drilled through the Greenland ice sheet, sediment cores from the North Atlantic Ocean, pollen records from both North America and Europe, and glacial deposits in North America. Paleoclimate records from the southern hemisphere also show climatic variability on millennial time scales. While interhemispheric synchrony has been observed for the last termination, the record of alpine glaciers and lake sediments in the Andes and New Zealand now suggest that these higher frequency changes may also be synchronous with the climatic fluctuations of the Northern Hemisphere. This award supports a project designed to model the higher frequency variations of climate. One of the challenges of developing such a theory for millennial-scale climate change will be to account for interhemispheric connections within the context of a global environmental system. While changes in the thermohaline circulation of the ocean have been postulated as a cause for rapid climate change on millennial time scales in and around the North Atlantic, interhemispheric synchrony would implicate the atmosphere as a key factor in global climate change on this time scale. |
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