Ice Core Paleoclimatology

Bona-Churchill, Alaska

Alaska - Bona-Churchill (2002)

Ice core reconstruction of North Pacific climate variability and environmental history from the Bona-Churchill Ice Field, Alaska. This project is funded by the National Science Foundation�s Office of Polar Programs (OPP-0099311) and is in its third year.

Photo by Lonnie Thompson Photo by Vladimir Mikhalenko

Bona-Churchill Brochure (3 pages)

This project was designed to retrieve and analyze ice cores from the col situated between Mt. Bona and Mt. Churchill (61o 24' N, 141o 42' W; 4420 m asl) in Wrangell-St Elias Mountains of southeastern Alaska. These records will fill a significant void in the high resolution climate history of this region. These new ice core records will complement and extend the existing tree ring-based climate records for the region and will add to the suite of high resolution ice core histories now emerging from other north polar ice fields. Global scale syntheses of past climate variability include ice core contributions from both Antarctica and Greenland as well as from ten lower latitude, high altitude sites in Tibet, South America and Africa. To date the unique paleohistories preserved in Alaska�s ice fields have not been tapped and thus have not contributed to this global climate synthesis. The sparseness of high resolution climate histories from the northeastern side of the Pacific Basin has been a major obstacle to advancing our understanding of the rapid and recent changes in the dynamical state of the Pacific region and its global teleconnections. The ice cores attained from the Bona-Churchill col will help fill this void and provide critical new insight to the climate history in this region.

Our scientific objectives for the Bona-Churchill cores include:

(1) Assess whether the warming of the last 30 years that appears to be amplified at high elevations in the tropics and subtropics extends to northwestern North America;

(2) Assess the character of the most recent �step� change in the dynamics of the Pacific Basin climate regime that occurred in 1976-77 and explore whether similar abrupt transitions have occurred in the past and if so, determine when and of what magnitude were the changes;

(3) Explore whether the recently identified multi-decadal ENSO-like mid-latitude climate variability has its roots in the tropical Pacific;

(4) Determine the bottom age of the ice on Bona-Churchill col; and

(5) Determine whether Mt. Churchill is indeed the source of the White River Ash.

The topics to the right provide more specific information about the various aspects of the project and selected photographs.