Our lab is primarily focused on developing a quantitative proxy for past sea ice extent and seasonal duration. We use fossil diatom assemblages as recorders of past sea ice to reconstruct the long-term (millions of years) record of sea ice in the Bering Sea. But, diatoms can tell us much more about past ocean conditions. In collaboration with others at UMass Amherst, Williams College, and Universidad de León we use a multi-proxy approach to untangle the story of ocean warming, changing primary productivity, and declining sea ice during previous intervals of climate warming.
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Why Study Sea Ice?
Sea ice is a defining feature of our planet. It serves as habitat for some of the most spectacular animals on Earth—polar bears, walrus, and ice seals—as well as for some of the smallest primary producers: sea ice diatoms. Declining sea ice has the potential to further increase global temperatures through the ice-albedo feedback. Dark open waters will absorb incoming radiation in contrast to the white surface of sea ice, which reflects solar radiation. Because of this, it is critical to understand how sea ice will decline as temperatures rise. One way to do this is to look at how sea ice changed in the past when the earth warmed due to natural forcings.
Diatoms are single celled, photosynthetic organisms that can live attached to the underside of sea ice, in waters surrounding sea ice, or in open waters. When they die and settle to the sea floor, their siliceous tests (cell walls) can be preserved in the sediments providing a record of past sea surface environments.