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| Titel |
Glacier response to North Atlantic climate variability during the Holocene |
| VerfasserIn |
N. L. Balascio, W. J. D'Andrea, R. S. Bradley |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 12 ; Nr. 11, no. 12 (2015-12-04), S.1587-1598 |
| Datensatznummer |
250117484
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| Publikation (Nr.) |
 copernicus.org/cp-11-1587-2015.pdf |
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| Zusammenfassung |
| Small glaciers and ice caps respond rapidly to climate variations, and records
of their past extent provide information on the natural envelope of past
climate variability. Millennial-scale trends in Holocene glacier size are
well documented and correspond with changes in Northern Hemisphere summer
insolation. However, there is only sparse and fragmentary evidence for
higher-frequency variations in glacier size because in many Northern
Hemisphere regions glacier advances of the past few hundred years were the
most extensive and destroyed the geomorphic evidence of ice growth and
retreat during the past several thousand years. Thus, most glacier records
have been of limited use for investigating centennial-scale climate forcing
and feedback mechanisms. Here we report a continuous record of glacier
activity for the last 9.5 ka from southeast Greenland derived from
high-resolution measurements on a proglacial lake sediment sequence. Physical
and geochemical parameters show that the glaciers responded to previously
documented Northern Hemisphere climatic excursions, including the "8.2 ka"
cooling event, the Holocene Thermal Maximum, Neoglacial cooling, and 20th
century warming. In addition, the sediments indicate centennial-scale
oscillations in glacier size during the late Holocene. Beginning at 4.1 ka,
a series of abrupt glacier advances occurred, each lasting ~100 years
and followed by a period of retreat, that were superimposed on a gradual
trend toward larger glacier size. Thus, while declining summer insolation
caused long-term cooling and glacier expansion during the late Holocene,
climate system dynamics resulted in repeated episodes of glacier expansion
and retreat on multi-decadal to centennial timescales. These episodes
coincided with ice rafting events in the North Atlantic Ocean and periods of
regional ice cap expansion, which confirms their regional significance and
indicates that considerable glacier activity on these timescales is a normal
feature of the cryosphere. The data provide a longer-term perspective on the
rate of 20th century glacier retreat and indicate that recent
anthropogenic-driven warming has already impacted the regional cryosphere in
a manner outside the natural range of Holocene variability. |
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