T97 The Impact of Climate Change on Hydrologic and Geomorphic Processes in the Arctic and Subarctic

Monday, 23 October 2006
1:30 PM - 5:30 PM

EXTENSION OF A MULTI-MILLENNIAL TREE RING SERIES FROM SOUTHERN COASTAL ALASKA USING SUBFOSSIL WOOD FROM GLACIER BAY NATIONAL PARK AND PRESERVE: A RECORD OF SUBARCTIC CLIMATE FORCING

Paper number: T97-2
Program: Technical Sessions
Time: 1:45 PM – 2:00 PM

Authors

Abstract

Few calendar-dated records of climate variability through the last 2,000 years are available for the subarctic North Pacific sector. Here we report on progress in the development of a multi-millennial tree-ring series and preliminary interpretation of its climatic significance. A remarkable set of subfossil trees radiocarbon-dated to intervals throughout the Holocene are preserved in the wake of retreating ice in Glacier Bay National Park and Preserve. Initial Glacier Bay tree-ring series are extracted from logs dating to the First Millennium AD (FMA) when they were overrun by advancing ice. The ring-width records from these trees are crossdated with a long tree-ring series from Prince William Sound, Alaska that extends into the 6th century AD. Together this exactly-dated, annual series spans almost 1800 years and provides an estimate of past temperature variability and contributes to the dating of glacier fluctuations and their response to this forcing.

The millennial to century-scale character of North Pacific climate is clear with cooling in the FMA, warming centered on AD 950, and intervals of cooling during the Little Ice Age between the 13th and 19th centuries. This ring-width record is one of inferred summer temperature and is consistent with the glacial record from land-terminating glaciers for the region, which is also considered as a proxy of summer temperature. Ongoing chronology development and dendroclimatic analysis provides a calendar-dated framework for glacier fluctuations in Glacier Bay and an independent record of temperature variability extending through the last several millennia.