Extending the Record of Arctic Sea Ice
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.
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.
Our lab includes a core lab where we can split and describe sediment cores as well as a wet lab area where we separate diatoms and other marine microfossils from sediment cores. It is equipped with both a compound microscope for quantitative diatom analysis and a stereomicroscope for examining biogenic and lithogenic core material. The compound microscope includes phase contrast and differential interference contrast (DIC) for resolution of small morphologic features. A Laser Diffraction Particle Size Analyzer capable of anaylzing the grain size of very small (< 0.5 g) sediment samples allows us to look for lithogenic signatures of sea ice and complements our microfossil analysis. In addition, we use the scanning electron microscope at ISU's Materials Analysis Research Lab for high resolution analysis of laminated sediment cores.