Collaborative Research: New Proxy Estimates of Arctic Sea Ice Coverage and its Biogeochemical Impacts in a Warmer World

The Arctic Ocean has experienced a significant loss in sea-ice coverage since the 1970s, with impacts on marine ecosystems, weather patterns, and economic activities such as fishing, shipping, and resource exploration. Understanding how Arctic sea-ice conditions have varied in the past provides valuable insights into natural patterns in ice coverage and helps refine scientific models used to project future ice cover. This project will investigate Arctic sea-ice cover during past warm periods in the geologic record using advanced geochemical techniques to reconstruct historical ocean conditions. The research will also support workforce development by training graduate and undergraduate students in cutting-edge scientific methods and equipping high school educators with new resources to enhance STEM education. This study will analyze ocean sediment cores to examine Arctic sea-ice coverage and ocean conditions over the past 150,000 years, focusing on two key warm intervals: the Holocene Thermal Maximum (~8,000 years ago) and the Last Interglacial (~130,000 years ago). The research team will use helium and thorium isotopes as a novel, inorganic method for estimating past sea-ice extent, while nitrogen isotope analyses of marine microfossils will provide insights into ocean nutrient levels and biological activity. These data will be collected from three sediment cores spanning a range of Arctic conditions, allowing scientists to assess changes in ice coverage, ocean structure, and nutrient cycling. By integrating these findings with existing data, the project will improve understanding of Arctic environmental history and enhance the accuracy of models used to study changing polar regions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.