| Summary: | Sea ice extent in the Arctic Ocean and its marginal seas is a key component of the coupled ice-atmosphere-ocean system and a driver of meridional ocean circulation, yet information about sea ice conditions in the past is very limited. The goals of this proposed study are two-fold. The first is to use archived surface sediments collected from the Bering and Chukchi Seas to develop quantitative measures of seasonal sea-ice extent and duration. This will be achieved through analysis of diatom morphology, assemblages and the IP25 biomarker of ice-associated diatoms from a suite of over 200 surface sediments collected from the Bering and Chukchi Seas spanning 0-12 months/year of sea ice. The second goal is to apply sea ice reconstructions using the calibrated diatom assemblage methods and IP25 analysis to a suite of six archived cores that form a latitudinal transect through the Bering and Chukchi Seas. The PIs aim to quantitatively reconstruct Late Pleistocene and Holocene seasonal sea ice extent at centennial-scale resolution. These efforts will be corroborated with independent biomarker-based evaluation of surface water temperatures. The successful completion of the project will result in a rich, multi-proxy data set that will be used to evaluate the sea ice and sea surface temperature history of the Bering Strait region. The results of this project will be relevant to global climate modelers as well as paleoecologists, paleoclimatologists, and paleoceanographers interested in regional- to global-scale forcing issues. The broader Arctic science community would benefit from the proxy development proposed. The project would support two full-time graduate students and a summer undergraduate research assistant in each year of the project. The PIs and students will also continue to develop curriculum modules designed to introduce 5th through 8th grade students to the topics of global and Arctic climate, marine sedimentation, ecosystem adaptation to changing environments, and the classification of organisms. The location of the 5 cores are as follows: HLY0202-3JPC: 60.1279N 179.4418W, HLY0202-51JPC: 54.55315N 168.66692W, HLY0202-17JPC: 53.933N 178.69883W, HLY0204-24JPC 73.231N, 167.88235W, HLY0204-28JPC: 73.44836N 167.69124W.
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