79NEXT: Is Ice Loss Triggered by Ocean Warming Extending to north Greenland?
Fiamma Straneo, Physical Oceanography
Richard Limeburner, Physical Oceanography
Arctic Research Initiative
2011 Funded Project
In the late 1990s glaciers in southern Greenland suddenly accelerated, thinned and retreated releasing large volumes of ice into the ocean and contributing to sea level rise. The widespread change was unexpected and unpredicted by ice sheet models. A decade later, the leading hypothesis is that the acceleration was triggered by increased submarine melting at the glaciers’ edge driven by warming ocean waters. Definitive conclusions are difficult to reach, however, since we have no measurements from the glacial fjords from the period prior to the glaciers’ acceleration and because our understanding of the submarine melting process is very limited. Now, there are signs that glaciers may also be changing in northern Greenland where satellite data recently shows thinning of the ice at the marine margins. Last summer an iceberg four times the size of Manhattan broke off from Petermann Glacier in northwest Greenland. Even so, few or no ocean measurements are being collected near the northern glaciers and, once again, we may be missing our opportunity to observe conditions before change occurs.
Here, we propose to fill this gap with 79NEXT (79 North EXperimentT) – a coordinated effort to map ocean and glacier conditions at the 79 North Glacier (79N or Nioghalvfjerdsfjorden) in northeast Greenland. This is one of Greenland’s largest glaciers and its characteristics make it particularly vulnerable to ocean warming, still the glacier shows no sign of change. Ocean data will be collected by drilling through the glacier’s 100 m ice tongue and deploying moored instruments (an ‘ice mooring’) into the 600 m ocean cavity beneath it. Glacier speed and surface melt conditions will be mapped using a network of GPS (Global Positioning System) units and two Automatic Weather Stations (AWS) on the ice. These measurements will provide an unprecedented record of ice/ocean dynamics in northern Greenland, that is crucial to improving our understanding of these coupled systems, and a baseline for comparison should the glacier undergo change.This project is made feasible by a concurrence of events: free access to an icebreaker and helicopter for the field work; availability of the controller system for an ‘ice mooring’ recently deployed in Antarctica, and no-cost GPS and AWS systems from our glaciologist colleague (Hamilton). The work builds on Straneo’s experience and knowledge in working at the margins of Greenland’s glaciers, including a 2009 pilot survey of 79N funded by WHOI’s ARI, and Limeburner’s recent successful development, deployment and recovery of a ‘satellite telemetered ice mooring’ below the Ross Ice Shelf in Antarctica. The observing system proposed here will be the first such system ever deployed in Greenland and will help establish WHOI’s leadership in designing and employing new real-time data technologies to overcome the challenges of wo