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Some time in February next year, if all goes as planned, about 20 unsuspecting seals in a remote part of Antarctica will have a sensor the size of a fist glued to the top of their heads.
This will not be the prettiest of sights. But the sensors on the deep-diving creatures are designed to pick up water temperature and salinity data that researchers hope will help answer one of the most urgent questions in climate science: how quickly could Antarctica lose enough ice to flood the world’s coastal cities and shores?
The blubbery conscripts are part of the first phase of one of the most sweeping scientific missions of its type: a £20m, five-year Anglo-American study announced this year that will explore the gigantic Thwaites Glacier in western Antarctica. The “doomsday glacier”, as Thwaites has been dubbed, flows down to the sea where it forms a floating ice shelf that helps to pin back a vast expanse of ice that would raise global sea levels by more than three metres if it ever collapsed completely.
Scientists already know from satellite images that Thwaites and nearby glaciers have been losing ice at an accelerating pace. Some researchers fear that warm water is melting the underside of the ice shelves so much that the glaciers are already in a process of unstoppable retreat. Others are less sure.
But the region in which Thwaites lies is so forbiddingly remote that, until now, researchers have struggled to get close enough to understand exactly what is happening, and therefore how much ice could be lost and how fast.
This uncertainty makes it hard to know how much global sea levels will rise in coming decades. The last big UN climate science report, published in 2013, suggested levels were unlikely to rise by more than one metre by the end of the century but conceded there was uncertainty about Antarctica’s ice.
Some researchers think that 2013 projection could be revised upwards as a result of the Thwaites mission.
“The question is by how much,” says Paul Cutler, programme director for the Thwaites project at the National Science Foundation in the US. “I think we would all like to see that there isn’t a big impact but we’re worried that there is.”
The National Science Foundation, with the UK’s Natural Environment Research Council, are deploying about 100 scientists to the project, which is full of logistical challenges. The nearest permanently occupied research station to the glacier is more than 1,600km away. Weather in the region was once thought so dreadful as to make field work impossible. Fewer than 50 people are believed to have ever set foot on Thwaites, says Mr Cutler, and reaching it is arduous.
“It’s one of the most inaccessible places on the planet,” says Karen Heywood, a professor of oceanography at the University of East Anglia. “To be honest, we know next to nothing about what’s happening under Thwaites.”
Prof Heywood was part of a team of scientists who in 2014 put sensors on seals in waters near the Thwaites glacier. The sensors last only a year: they are lost when the seals shed fur in their annual moulting season. But that move led to two important findings: the creatures stay in the area all winter and, crucially, dive in places near the ice shelf where researchers need to understand much more about warmer water.
It is known that warm water comes from the deep ocean further offshore. But Prof Heywood says it is still unclear what drives the water towards the floating ice shelf, how fast it flows, or where it flows in and out. “We know that it goes in warm and comes out colder, having given up some of its heat to melt the ice above it,” she says.
Thwaites scientists will also use autonomous underwater vehicles to explore underneath the ice. In later seasons, that will include the British Antarctic Survey’s Boaty McBoatface.
‘Joke’ boat takes a lead in polar research
“Boaty McBoatface” is a remotely operated autonomous underwater vehicle that received its odd moniker after UK authorities invited the public to vote on a name for a much grander £200m polar research ship in 2016.
To ministers’ horror, the votes were overwhelmingly in favour of Boaty McBoatface. After much hand-wringing, it was decided to override the will of the people and give the larger ship the name of the RSS Sir David Attenborough, while naming the underwater sub Boaty.
But the remote nature of the glacier means a lot of the work in this first phase of the Thwaites project this Antarctic summer will be preparatory. Fuel, equipment, food and other supplies needed for research work will be dropped off at a base near the glacier where planes can land on the snow.
The British Antarctic Survey research institute, meanwhile, will drag in heavy equipment and supplies to Thwaites from the coast hundreds of miles away in a convoy of sledges pulled by tractors.
This is not work for the faint of heart. The convoy field guides will use ice radar to make sure they are not about to plunge into one of the crevasses that are a constant source of concern for anyone working in the Antarctic.
“This is a big and complicated project in a tough part of Antarctica. It’s essential that in this first season we hit the ice running,” says Professor David Vaughan, UK lead scientific co-ordinator for the Thwaites mission.
“Thwaites Glacier holds the key to a much better understanding of sea level rise. This is our first chance to get a deeper understanding of this ‘wild card’ in West Antarctica.” As the Thwaites mission gets under way, British scientists will fly over the glacier in smaller Twin Otter aircraft in January to map it and get a better idea of the best sites for future field work.
Other researchers on the US icebreaker vessel, the Nathaniel B Palmer, will map the sea floor around Thwaites to see how the shape of the bed affected the glacier’s behaviour in the past.
They will also collect sediment cores from the seabed to see when the glacier last retreated, and what environmental factors drove the decline. Separately, scientists will collect samples from nearby islands that will be analysed to see how sea levels have changed in the past 5,000 years.
It will be some years before all the results are known. Once they are, scientists should be able to produce a more accurate picture of the future — and the extent to which large swaths of the world’s densely populated coastlines are at risk from rising sea levels.
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