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Adam Csank
Ph.D 2011
Contact Information: Department of Geography University of Nevada- Reno
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DECIPHERING
ARCTIC CLIMATE IN A PAST GREENHOUSE WORLD: MULTIPROXY RECONSTRUCTIONS
OF PLIOCENE CLIMATE Department
of Geosciences ABSTRACT The extreme sensitivity of high latitudes to global climate changes is the stimulus for the study of ancient Arctic ecosystems under greenhouse conditions. With an increasing number of studies, including the most recent Intergovernmental Panel on Climate Change (IPCC) report, highlighting Pliocene climate as an analogue for future warmth, the need for accurate proxy records for this period is crucial. In order to investigate Pliocene climate I used stable isotopic studies of fossil molluscs, moss and wood from two fossil forests deposits in the Canadian High Arctic. I found that during the early Pliocene Ellesmere Island growing season temperatures were 10-14° C warmer than at present. I also found that mean annual temperatures (MAT) were 17-19° C warmer than present. That the difference from modern in MAT was greater than the difference in growing season temperatures is an indication that Pliocene winter temperatures were considerably warmer than summer temperatures. Spectral analysis of the tree ring data indicated that decadal and sub-decadal variability similar to modern patterns existed in the Pliocene Arctic. Mean annual temperatures from a late Pliocene-early Pleistocene site on Bylot Island, during the transition to large scale Northern Hemisphere glaciation, were 11.8° C warmer than present. This deposit represents the remains of a flora that grew during an interglacial warm period where summer insolation was at a maximum. This suggests that prior to using such sites as true analogues of future conditions we may need to consider how close the feedbacks operating then were to the feedbacks we might expect in the future. However, that temperatures so much warmer than present existed in the high Arctic during a period. |
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