Alaska Section, American Water Resources Association

Tom Douglas, Alaska Section AWRA Northern-Region Director

This is a tentative list of winter speakers for AWRA, Northern-Region Section. Dates and locations vary and are subject to change for the 2003 talks, and we will make every attempt to keep you informed of any changes as they occur. We plan to send an email out the Monday prior to each talk, so if you have not been receiving E-mails and wish to, please contact Tom Douglas at (907) 353-9555 or Thomas.A.Douglas@erdc.usace.army.mil. Brownbag talks are from 12:00 pm to 1:00 pm on the second Wednesday of each month. We meet in the conference room at the Department of Natural Resources, 3700 Airport Way (across from the Airport Way Fred Meyer Store).

January 8th, 2003

D.C Trabant
U.S. Geological Survey

Why is Hubbard Glacier Growing and Advancing?

In stark contrast with the majority of glaciers in Alaska that are losing volume and retreating in response to climate forcing, about 5 large glaciers are increasing in volume and advancing. All of these are calving glaciers that are advancing into seawater. Hubbard Glacier, at the head of Disenchantment Bay near Yakutat, Alaska, is one of the advancing glaciers and is the largest calving glacier on the North American Continent. Hubbard Glacier's current advance began shortly before 1895 and has recently been newsworthy because its advance blocked the entrance to Russell Fiord between June and August 2002.

Calving glaciers that are currently growing and advancing have at least four things in common. All of them (1) are at the heads of long fiords, (2) have undergone massive retreats during the last thousand or more years, (3) presently calve over relatively shallow moraine shoals, and (4) have strongly positive mass balances that are a consequence of a surface-area distributions that have unusually small ablation areas compared to the accumulation areas.

Glaciologists often point out that glaciers are sensitive indicators of climate. We'll discuss why this paradigm should not be applied to calving glaciers. As a point to think about, the calving glaciers that are currently growing and advancing in the face of global warming, were retreating throughout the little ice age.