Graubard Fellowship Supports Reconstructing Past Arctic Sea-Ice Coverage
The Arctic region is warming nearly four times faster than the rest of the planet. Consequently, sea-ice coverage has reduced rapidly, with the summer minimum September sea-ice declining by about 40% since 1979. Sea-ice loss threatens the food security and infrastructure of coastal communities, drives unresolved changes in biological productivity, and promotes further global warming through ice-albedo feedback. However, model projections of the timescale of Arctic sea-ice decline and the resulting changes to the Arctic ecosystem vary widely. Observations from the geologic past can serve as critical benchmarks for ground truthing climate model projections of future sea-ice decline. Within the past 150,000 years, there have been two time periods that can act as analogs for future warm conditions in the Arctic: the Holocene Thermal Maximum (9,500 to 5,500 years ago) and the Last Interglacial (130,000 years ago). During both of these time periods, the Earth was several degrees hotter than today.
With support from the Graubard Fellowship and the broader Program on Climate Change community, I have been using a newly developed sea-ice proxy to map out sea-ice coverage in the Arctic Ocean over the past 150,000 years in order to understand how sea-ice behaves during periods of drastic climate change. The sea-ice proxy is based on the presence of cosmic dust grains in marine sediment cores. As cosmic dust falls from space, it settles on the Earth’s surface. In the Arctic, sea-ice blocks dust from entering the ocean but when sea-ice is absent, that cosmic dust accumulates in seafloor sediment. I use mass spectrometry to detect the unique isotopic signatures of cosmic dust in Arctic sediment and track how ice coverage is changing through time. I have been able to collaborate with scientists at other institutions on this project and create vital connections with other researchers in paleoceanography and polar science. I look forward to continuing these collaborations and engaging further with the Program on Climate Change in my future work.
Written by Tara Kalia. Tara is a second-year PhD student in the School of Oceanography. She studies high latitude paleoenvironments with a focus on sea-ice reconstructions. She is a PCC Graduate Student Representative.