Scientists working in Antarctica are feeling the impact of climate change in ways the public might find surprising. Although global warming is causing Arctic ice to melt and glaciers around the world to shrink, the problem in Antarctica is that the sea ice surrounding the continent is increasing and now hampering ship navigation and resupply operations. This week, scientists and logistics experts from the 30 nations working on the continent are meeting in Hobart, Australia, to exchange ideas on coping with the sea ice challenge.
The underlying mechanism is fairly well understood, says Tony Worby, a sea ice specialist at the Antarctic Climate and Ecosystems Cooperative Research Centre. "We know that the changing Antarctic sea ice extent is very largely driven by changes in wind,” he says. “In turn, we know those changes are driven by the depletion of ozone in the stratosphere as well as increasing greenhouse gases at the surface." The new wind patterns blow Antarctic sea ice away from the continent and then more ice forms close to shore. This doesn't occur in the Arctic because the ocean is hemmed in by land masses. And "it's quite a lot windier around Antarctica than in the Arctic," Worby says.
The area covered by Antarctic sea ice has been growing roughly 1.2% each decade since 1979. Last September, it reached a record 20 million square kilometers surrounding the 14 square kilometer continent. The combined 34 million square kilometers of ice at the end of the austral winter is more than 3.5 times the area of the United States.
But understanding the phenomenon doesn’t help ship captains. "It's very difficult to predict sea ice conditions in the same way that we predict weather," Worby says. Current models are inadequate, particularly when it comes to predicting ice thickness, a key parameter for ships and ice breakers. And icebergs are a wild card. They are not only an ever-present mobile hazard for ships, but if grounded on the coast they can also seed a long-term buildup of ice.
For scientists working on the continent, sea ice has become a major logistical headache. Most research stations are located on the coast, and shippers previously counted on the ice breaking up so their vessels could get near shore, says Rob Wooding, general manager of operations for the Australian Antarctic Division in Kingston. But that hasn’t happened for several years at Australia’s Mawson station, says Wooding, who is also vice-chair of the workshop sponsor, the Council of Managers of National Antarctic Programs. "In the 2013 to 2014 season we couldn't get anywhere near Mawson due to the sea ice; we had to get fuel in there by helicopter," he says. But helicopters are not a long-term solution because of their cost and limited capacity.
That same season, the Russian vessel M.V. Akademik Shokalskiy became trapped in sea ice while carrying a team of Australian researchers and some tourists. Ice breakers from three nations attempted in vain to reach the vessel, although scientists and passengers were rescued by helicopter. Shifting winds allowed the ship to break free after a harrowing 10 days. "It's inevitable that ships will get stuck, but better [sea ice] forecasting will ensure that ships don't get stuck as often," Worby says.
The issues of forecasting and logistics dominate the agenda of this week’s workshop. Worby would like to be able to give captains 1 to 3 days’ notice of what ice conditions to expect. Doing so will require better modeling of the interaction of ice formation, winds, and currents. Unfortunately, improving the models requires observations, and "Antarctica and the sea ice lanes are some of the most data sparse regions on earth," he says. They would also need more computing power to crunch the numbers. "Those things are achievable, but it’s going to take some sustained effort," he says.
On the logistics side, Wooding says large cargo planes or hovercraft could ease the pinch, but that most of the discussion will focus on "operating over the ice rather than breaking through the ice into a harbor." In the long term, he thinks that the need to ensure reliable supply lines might lead to some rethinking of where to locate research bases. But neither he nor Worby foresees any country giving up on Antarctic research.