NOAA/WDS Paleoclimatology - Bona-Churchill Ice Core, Alaska 800 Year d18O Data

Stable oxygen isotopes (d18O) in the Bona-Churchill (B-C) ice core from southeast Alaska provide a valuable, high-resolution history of climate variability and sea ice cover in the Western Arctic over the last 800 years. Multiple ice cores have been collected from the Wrangell-St. Elias Mountain Range; however, their d18O records exhibit little consistency as each core offers a unique view on local, regional, and/or global climate variability. To explore the primary mechanisms influencing the isotopic signature at the B-C site, we utilize isotope-enabled model data, reanalysis data, and observations which all indicate a strong connection between isotopes at the B-C site and Western Arctic climate, likely established by the location of the storm track in this region. Enriched B-C d18O reflects increased southerly flow and warmer waters in the Bering Sea which modulates the heat flux through the Bering Strait and into the Arctic, thereby affecting sea ice cover in the Western Arctic. The B-C d18O paleorecord shares some remarkable similarities (r = -0.80, p < 0.001) with the duration of Western Arctic sea ice cover reconstructed from a Chukchi Sea sediment core. Interestingly, during the Little Ice Age enriched d18O and reduced Western Arctic sea ice are observed and may be indicative of prolonged periods of the warm Arctic/cold continents pattern and a northwestward shift of the North Pacific storm track.