Collaborative Research: Marine Climate and Relative Sea Level Across Central Beringa

Investigator: Julie Brigham Grette  juliebg@geo.umass.edu (Principal Investigator current)          

Abstract

Abstract OPP-99-12122 Keigwin OPP-00-02643 Brigham-Grette

The broad region of Beringia is separated by the Bering Strait.  North Pacific waters rich in nutrients flow northward along the eastern Bering Sea continental slope, across the shelf and into the Chukchi Sea, sustaining high surface water.  The Pacific waters also contribute about 30 percent of the Arctic Ocean's fresh water budget (about half of the river's contribution) which helps maintain the Arctic halocline, Arctic sea ice, and regulates climate in the North Atlantic region.  During the last glacial maximum (LGM), sea level was lowered by 125 meters, Beringia was much larger and the Pacific and Arctic Oceans were separated by nearly 1000 kilometers.  Beringian climate was more uniform because the sea was so distant.

The exact role of the ocean in controlling Beringian climate is unknown because of the lack of data on the surrounding seas.  The history of relative sea level is poorly known, but is likely to have differed from eustatic sea level because of tectonic and possible glacio-eustatic effects.  Sea surface conditions such as ice extent, temperature, and salinity are likely to influence the climate through albedo effects, heat exchange, and humidity, but there are almost no high-resolution proxy data for these properties in the Bering and Chukchi Seas.  To link the marine and terrestrial realms in Beringia, the Principal Investigators will participate in a field program of gravity, piston and vibracoring in the Bering and Chukchi Seas to develop high resolution records of 1) intermediate ocean ventilation in the Bering Sea; 2) surface ocean temperature, salinity, sea ice extent, and history of iceberg discharge in both the Bering and Chukchi Seas; and 3) relative sea level in the Bering Strait region since the LGM.  These objectives are closely aligned with the theme of the October 1999 NSF-sponsored workshop on "Assessing Impacts of Arctic Bathymetry Changes and Fresh Water Inputs on Shelf and Ocean Circulation for the Past 20,000 Years."