13 September, 2013

Antarctic research details ice melt below massive glacier

An expedition of international scientists to the far reaches of Antarctica’s remote Pine Island Glacier has yielded exact measurements of an undersea process glaciologists have long called the “biggest source of uncertainty in global sea level projections.”

In a paper published in Science magazine, the research team, led by Naval Postgraduate School (NPS) Department of Oceanography Research Professor Tim Stanton and University of Alaska Department of Physics Professor Martin Truffer, details the landmark results of the Pine Island Glacier expedition, giving scientists an extensive look beneath the ice at one of the most remote research sites on the planet — a site whose fate could affect the lives of millions.

Professors Stanton and Truffer have spent years working with colleagues from Pennsylvania State University, NASA, the British Antarctic Survey and New York University, supported primarily by the National Science Foundation, to understand what is happening beneath Pine Island Glacier.

Given the flow of warm sea water below the glacier, scientists have long known that Pine Island Glacier was melting from below — the accelerated flow of Western Antarctic Ice Shelf glacial ice into the Amundsen Sea has been a concern of scientists since the late ‘80s. An exhaustive expedition to the 50km-long floating ice shelf at the outer reaches of the glacier field, and 500 meters down into it, reveal the first measurements detailing ice-shelf melting rates and processes within melt channels bore into the shelf underbelly

Professor Stanton says,

“Fresh water forms every time [the sea] injects heat into the shelf. The warm water starts to melt the ice at the grounding line and creates a buoyant plume called a boundary layer current. We measured the affects of that current for the first time.

“What we have brought to the table are detailed measurements of melt rates that will allow simple physical models of the melting processes to be plugged into computer models of the coupled ocean/glacier system. These improved models are critical to our ability to predict future changes in the ice shelf, and glacier melt rates of the potentially unstable Western Antarctic Ice Sheet in response to changing ocean forces.”

The measured glacial melt rate at the site, and through the channel on Pine Island, at approximately six centimeters per day, reveals a critical need to understand channelized melting underneath massive glaciers, as they are major contributors to global sea-level rise now and into the future.

BAS scientist Hugh Corr, a co-author on the paper, says,

“The role of British Antarctic Survey was to deploy a specially designed radar and directly measure the spatial pattern of thinning across the ice shelf.

“The technique works by the equipment having the precision to accurately track the phase of the radar-echo coming from the ice-ocean boundary. The detail in the echo from locations where the melt-rate is high made it possible to observe, in real time, the dynamic melting of the ice-shelf.”


Mission and Functions of the Naval Postgraduate School

Provide relevant and unique advanced education and research programs to increase the combat effectiveness of commissioned officers of the naval service to enhance the security of the United States. In support of the foregoing, and to sustain academic excellence, foster and encourage a program of relevant and meritorious research which both supports the needs of Navy and Department of Defense (DOD) while building the intellectual capital of NAVPGSCOL faculty.

The Naval Postgraduate School

The NPS team has a website dedicated to the PIG team’s work.