Cenozoic evolution of the northern Greenland Ice Sheet exposed by transect drilling in northeast Baffin Bay1
1 Knutz, P., Jennings, A., and Childress, L.B., 2022. Expedition 400 Scientific Prospectus: NW Greenland Glaciated Margin. International Ocean Discovery Program. https://doi.org/
Elucidating the long-term history of the Greenland Ice Sheet (GrIS) is essential for understanding glacial instability thresholds, identified as major climate system tipping points, and how the cryosphere will respond to anthropogenic greenhouse gas emissions. To address current knowledge gaps in the evolution and variability of the GrIS and its role in Earth's climate system, International Ocean Discovery Program (IODP) Expedition 400 will obtain cores from seven sites across the northwest Greenland margin into Baffin Bay where thick Cenozoic sedimentary successions can be directly linked to the evolution of the northern GrIS (NGrIS). The strategy of drilling along this transect is to retrieve a composite stratigraphic succession representing the Late Cenozoic era from the Oligocene/Early Miocene to Holocene. The proposed sites will specifically target high–accumulation rate deposits associated with contourite drifts and potential interglacial deposits within a trough mouth fan system densely covered by seismic data. We seek to test if the NGrIS underwent near-complete deglaciations in the Pleistocene and to assess the ice sheet’s response to changes in orbital cyclicities through the mid-Pleistocene transition. Paleoclimate records will be obtained that can provide chronology on the NGrIS expansion and unravel potential linkages between marine heat transport through Baffin Bay and high Arctic warmth during the Pliocene. A deep coring site (980 meters below seafloor) targeting a Miocene and Oligocene strata succession will examine possible linkages between changes in atmospheric CO2 and climate-ecosystem conditions in Greenland. The overall aim is to investigate the full range of forcings and feedbacks—oceanic, atmospheric, orbital, and tectonic—that influence the GrIS over a range of timescales, as well as conditions prevailing at the time of glacial inception and deglacial to interglacial periods. The data and results gathered from Expedition 400 will effectively constrain predictive models addressing the GrIS response to global warming and its impending effects on global sea levels.
Sea-level consequences of anthropogenic climate forcing hinge on how the polar ice sheets respond to global warming. If fully melted, the Greenland Ice Sheet has the potential to raise sea level by >7 meters, yet we know very little about its long-term responses to past climate warming or its role in Earth’s climate system. Expedition 400 seeks to address current knowledge gaps in the evolution and variability of the northern Greenland Ice Sheet by analyzing sedimentary archives of warm and cold periods of the last ~30 million years, including times when the greenhouse gas content of the atmosphere was higher than it is today.
Sediment archives will be obtained by drilling at seven sites to depths of 300–1000 meters below seafloor along a transect crossing the northwest Greenland margin into Baffin Bay. The seven sites will provide a composite stratigraphic succession that includes preglacial settings, a record of first growth of the northern Greenland Ice Sheet, and glacial and interglacial cycles when the ice sheet grew to its maximum positions at the shelf edge and retreated toward land, possibly melting nearly completely.