Expansion of alpine glaciers in Pacific North America in the first millennium A.D.
- Alberto V. Reyes1,
- Gregory C. Wiles2,
- Dan J. Smith3,
- David J. Barclay4,
- Sandra Allen5,
- Scott Jackson5,
- Sonya Larocque5,
- Sarah Laxton5,
- Dave Lewis5,
- Parker E. Calkin6 and
- John J. Clague7
- 1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada
- 2Department of Geology, The College of Wooster, Wooster, Ohio 44691, USA
- 3University of Victoria Tree-Ring Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia V8W 3P5, Canada
- 4Department of Geology, State University of New York, Cortland, New York 13045, USA
- 5 University of Victoria Tree-Ring Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia V8W 3P5, Canada
- 6Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309, USA
- 7Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
Abstract
Radiocarbon ages and lichen-dated moraines from 17 glaciers in coastal and near- coastal British Columbia and Alaska document a widespread glacier advance during the first millennium A.D. Glaciers at several sites began advancing ca. A.D. 200–300 based on radiocarbon-dated overridden forests. The advance is centered on A.D. 400–700, when glaciers along an ∼2000 km transect of the Pacific North American cordillera overrode forests, impounded lakes, and deposited moraines. The synchroneity of this glacier advance and inferred cooling over a large area suggest a regional climate forcing and, together with other proxy evidence for late Holocene environmental change during the Medieval Warm Period and Little Ice Age, provide support for millennial-scale climate variability in the North Pacific region.
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- Received 26 May 2005.
- Accepted 23 September 2005.
- Revision received 21 September 2005.
- Geological Society of America
