Drilling glacial deposits in offshore polar regions

High latitudes are of fundamental importance in the Earth's climate system—they house ice sheets that govern global sea level heights, influence how much solar energy is reflected back to space, and create deep and bottom waters that drive the ocean's ability to circulate energy and nutrients across the globe.

High latitudes are of fundamental importancein the Earth’s climate system they house ice sheets that govern global sea level heights, influence how much solar energy is reflected back to space, and create deep and bottom waters that drive the ocean’s ability to circulate energy and nutrients across the globe.Not surprisingly, understanding future climate change requires knowledge of how past rapid climate changes influenced high latitudes. Under what conditions did ice streams advance and retreat? Did deep and bottom water formation ever slow down or stop and why? What was the precise timing of these changes, and how rapidly are the interacting components in the polar systemresponding?To help answer these questions, scientistsseek to drill into the seafloor within highlatitudes. The depositional succession in sediment cores recovered may be able to tell the story of how high latitudes evolved through past climate change knowledge that could help us anticipate how the high latitudes will respond to or push future climate changes.However, ocean drilling in high latitudes is no easy task. The physical characteristics ofglacial tills and related marine deposits, witha highly consolidated cohesive matrix, hindersuccessful sediment coring because the sticky, clayey material of these deposits clogs the rotating drilling mechanisms.To overcome this challenge, scientists are investigating how drilling systems can be tailored for use on the high- latitude seafloor (see also the extended version of this article in the additional supporting information in theonline version of this article). One, developedby Germany’s MARUM—Center for Marine Environmental Sciences, is a specialized drill rig. Nicknamed MeBo, from Meeresboden-Bohrgerät (German for “seafloor drill rig”), the device can drill into soft sediments, hard rocks, and a combination of the two [Freudenthal and Wefer,2013]. Most important, it is portable, meaning that it can be deployed from scientific research vessels, reducing the need for specialized and expensive drilling vessels.MeBo was recently used on the Ice Dynamics and Meltwater Deposits: Coring in the Kveithola Trough, Northwest Barents Sea expedition. Nicknamed CORIBAR, the expedition took place on the R/V Maria S. Merian [Hanebuth and Expedition Team, 2013]. In 2013, the device drilled two boreholes, each longer than 35 meters, through tills and glacigenic deposits in the Kveithola Trough of the western Barents Sea, south of Svalbard. The project showed that obtaining marine sediment cores and borehole logs from glacial deposits remains technologicallychallenging. Nevertheless, this first- ever deploymentof MeBo in the Arctic region has given scientists a basic idea of the climaterelatedglacial history of the region.