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Helen Underwood

This project seeks to investigate how the Greenland Ice Sheet (GIS) has affected weathering in the past under a range of climatic boundary conditions.

PhD project title:

Interglacial instability of the Greenland ice sheet and its impacts on climate.

Project description:

Helen Underwood
The Greenland Ice Sheet (GIS) has changed in extent over glacial-interglacial cycles and is likely to change in the future with rising temperatures, with implications for global sea level and the coupled ocean-atmosphere-climate system. To better constrain future changes, it is important to understand how the ice sheet has responded to various climate forcings in the past. In addition, the role of ice sheets in the carbon cycle, through chemical weathering and nutrient delivery to the oceans, is now receiving increased attention. Glacial-interglacial weathering variations in Greenland are poorly understood, so this project seeks to investigate how the GIS has affected weathering in the past under a range of climatic boundary conditions.

The project will focus on the extended warmth of interglacial marine isotopes stage (MIS) 11 (~424-374 ka), and on weaker interglacials from MIS 13 to MIS 19 (478-790 ka). Laboratory experiments on samples from marine sediment cores IODP U1305 and ODP 919 will be used to extract authigenic (seawater-derived) and detrital (terrestrial-derived) components. Detrital Sr-Nd-Pb isotopes will be used to constrain past changes in the GIS extent and rates of change, while authigenic Pb isotopes and detrital Li isotopes will help trace changes in the rate and style of chemical weathering.

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