This undated photo courtesy of NASA shows Thwaites Glacier in Western Antarctica. (AFP PHOTO/NASA/HANDOUT)

This story has been updated.

U.S. and British science agencies Thursday announced a multimillion-dollar research mission to study an enormous and exceedingly remote Antarctic glacier, one that they say could hold the potential for major sea level rise before the end of the century.

The move suggests that even as world governments move to tackle greenhouse gas emissions, their polar research arms are racing to get a handle on perhaps the most sweeping potential consequence of a changing climate — a large increase in global sea level due to the loss of polar ice — and determine just how rapidly it could arrive. And they appear to have singled out the number one point of vulnerability.

The glacier in question, named Thwaites, is a linchpin of the West Antarctic ice sheet. It is larger than Pennsylvania and presents a 75-mile-long front to the ocean, in this case the Amundsen Sea, where recent studies have suggested that warm waters at extreme depths are causing a major glacial retreat that could be “unstoppable,” in the words of NASA. The reason is that these Amundsen Sea glaciers are already sitting in deep water, but if they break away further, the terrain becomes even deeper behind them, threatening a runaway retreat.

“Recent studies indicate the greatest risk for future rapid sea-level rise now arises from Thwaites Glacier due to the large changes already underway, the potential contribution to sea-level rise, and the societally relevant time scales of decades to centuries over which major, irreversible changes are possible in the system,” notes the joint research solicitation from the U.S. National Science Foundation and the British Natural Environment Research Council.

In a press statement, the National Science Foundation suggested the cost of the research itself will be $20 million to $25 million but that “allocation of logistics support for field work would increase that commitment significantly.”

While it isn’t entirely clear yet how scientists would tackle Thwaites, the logistical requirements are considerable. “I can envisage ships, I can envisage camps on the glacier itself, there’s going to be aircraft flying missions over, and possibly helicopters,” said Paul Cutler, the program director for Antarctic Integrated System Science at the NSF’s Division of Polar Programs. “From the ships, there will probably be autonomous underwater vehicles, underneath the ice shelf. It’s up to the imagination of the scientists to make the best case, and we’ll work, to the extent we can, to make that happen.”

Like many or most Antarctic glaciers, Thwaites consists of both a large ice “shelf,” or a floating part of the glacier that sits on top of the ocean, and then a far larger area where the glacier rests firmly on the seafloor. The glacier’s “grounding line,” where it first touches the seafloor, is currently at 300 and 700 meters below sea level, or just under half a mile at most, according Robin Bell, an Antarctic researcher at Columbia University’s Lamont-Doherty Earth Observatory.

But if Thwaites were to retreat backward, there are regions of West Antarctica where the ice rests more than 2,400 meters below sea level, or about a mile and a half. A retreat has already begun: Between 1992 and 2011, the Thwaites grounding line retreated inland 8 miles, a 2014 study found.

The photograph above shows an edge of the Thwaites Ice Shelf. (NASA photograph by Jim Yungel.)

Vast additional volumes of the glacier and the West Antarctic Ice Sheet rest above sea level, and this is where the major contribution to sea level rise would come from. According to NSF, Thwaites is already contributing an astonishing 10 percent of all global sea level rise. The fear is just how much this could increase.

Thwaites itself could ultimately contribute around two feet to the global sea level if it were to be lost entirely. But it also connects with the interior of the West Antarctic ice sheet. The entirety of West Antarctica could contribute more than 3 meters, or more than 10 feet, of sea level rise if it were to melt entirely into the ocean.

The National Science Foundation’s Cutler said the reason this is such a major initiative is that Thwaites glacier is extremely remote, and the approach to it by sea is often blocked by floating sea ice. “Geographically, there is no permanent station within about 1,000 miles,” he said. The U.S. has scientific bases on the Antarctic peninsula and near the Ross Ice Shelf, but the Amundsen Sea is roughly equidistant between the two.

The research initiative, although not yet finalized at that time, was discussed publicly at an annual meeting of West Antarctic scientists in Sterling, Va., earlier this month. The need for the study initiative had bubbled up from this group of scientists, dubbed the West Antarctic Ice Sheet Initiative, who had increasingly reached a consensus that Thwaites is the glacier that could really change current sea level forecasts.

At that meeting, David Vaughan, the science director of the British Antarctic Survey part of the Natural Environment Research Council, said the initiative is “probably the biggest thing that’s happened in our area of science in terms of a real opportunity to get out there and make measurements that we’ve never been able to make before.”

The National Environmental Research Council has recently conducted an extensive study of another very large glacier next to Thwaites, called Pine Island glacier, which is also a major sea level risk and already retreating substantially. But Pine Island glacier has a much narrower front exposed to the ocean and does not as immediately connect to the center of the West Antarctic Ice Sheet, which has led scientists to increasingly train their attention on the wider and less studied Thwaites.

The research solicitation says that $20 million or more will be spent on five-to-eight research awards that will involve data collection in the harsh and remote environment of Thwaites itself. Scientists must apply for the research grants by describing how they would attempt to study the glacier in such a way as to advance our understanding of how much ice it could lose, and how quickly that could occur.

“The resources provided by this initiative will allow intensive study of the glacier that has perhaps the greatest potential to affect sea-level and change on time scales relevant to human societies (decades to centuries),” said Knut Christianson, an Antarctic scientist at the University of Washington in Seattle, in an email comment on the new initiative.

Christianson added that “a large investment of resources, like this one, will allow us to make substantial progress on understanding the components of the Thwaites Glacier basin system that cannot be studied via satellites.”

Scientists could learn more, said Christianson, about what kind of terrain it is lying on, and how the ocean is contributing to its melting. Such inquiries may — or may not — suggest reasons that Thwaites may find some source of stability, rather than just continuing an unstoppable retreat.

Getting “up close and personal” with the glacier, added the Lamont-Doherty Earth Observatory’s Robin Bell by email, will help researchers close “critical data and knowledge gaps.”

“This international program call will enable a focused effort to fill these gaps by enabling a serious effort to get into the Thwaites regions,” Bell continued. “The program is based on broad community input and is the first step to improving our forecast of how fast sea level will rise globally in the coming decades and centuries.”

“The evidence is amassing that we really need to understand this better, so that we know where we’ll be in people’s lifetimes, basically,” said the NSF’s Cutler.

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