United States and British science agencies yesterday announced a multi-million dollar research mission to study an enormous and remote Antarctic glacier that is already showing accelerating ice loss and could trigger a major rise in sea levels before the end of the century.
The move reflects the growing sense of urgency around the world about understanding one of the biggest consequences of a warming globe - the melting of polar ice and its impact on the oceans.
The glacier in question, named Thwaites, acts as a kind of linchpin to the West Antarctic ice sheet. It is larger than Pennsylvania and presents a 120km 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 Nasa once described as "unstoppable". Such a retreat could lead to a significant increase in sea levels.
"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 Paul Cutler, the programme director for Antarctic Integrated System Science at the NSF's Division of Polar Programmes.
Investigating the pace of that breakup is a complex undertaking; the closest permanent research station is 1600km away and the approach to the glacier by sea is often blocked by floating sea ice.
The mission is expected to take several years to unfold. In a press statement, the National Science Foundation suggested the cost of the research itself will be US$20-$25 million ($27.9m-$34.9m), but that "allocation of logistics support for field work would increase that commitment significantly". The final tally will depend on how scientists propose to tackle the problem.
"I can envisage ships, I can envisage camps on the glacier itself, there's going to be aircraft flying missions over, and possibly helicopters," Cutler said. "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."
Setting up shop is just part of the logistical challenge. Conducting research on the glacier itself poses its own complications.
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 300m and 700m below sea level, according Robin E Bell, an Antarctic researcher at Columbia University's Lamont-Doherty Earth Observatory, but if it continues to retreat it could enter far, far deeper waters.
Warming waters are weakening the glacier, causing portions to break off. A retreat has already begun: Between 1992 and 2011, the Thwaites grounding line retreated inland 13km, a 2014 study found.
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 per cent of all global sea level rise. The fear is just how much this could increase.
Thwaites itself could ultimately contribute around 60cm 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 3m of sea level rise if it were to melt entirely into the ocean.
The research initiative, although not yet finalised at that time, was discussed publicly at an annual meeting of West Antarctic scientists in Sterling, Virginia, 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 Vaughn, the science director of the British Antarctic Survey, which is 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 centre 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 US$20m 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.
Knut Christianson, an Antarctic scientist at the University of Washington in Seattle, said in an email 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, Christianson said, about what kind of terrain it is lying on, and how the ocean is contributing to its melting. Such inquiries may 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". "The programme 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," Bell wrote.