As seen from space, the Arctic ice cap looks and acts like a giant amoeba splayed across the top of the world. It heaves and twists, reaches outward, then shrinks back.
“It’s constantly in motion,” says David Barber, while a time-lapse sequence of polar satellite images plays across his computer screen.
The more scientists study the sea ice that floats atop the Arctic Ocean, the more it resembles something that lives and breathes, a dynamic membrane that hosts microbial communities, fosters chemical reactions and connects air with water in surprising ways.
“It’s not just a cap, it’s an active participant in the system,” says Dr. Barber, who is director of the University of Manitoba’s Centre for Earth Observation Science. “That has global implications.”
Those implications matter to marine life, planetary weather patterns, human health and northern development – more than enough reason for the Arctic sea ice to warrant scientific attention. It has also motivated a major expansion at the centre, backed by a $10-million Canada Excellence Research Chair and $48-million in additional funding. The centre now has more than 100 scientists, graduate students and technicians, making it the world’s largest research group focused on sea ice.
But even as the centre celebrates the opening of $15-million, state-of-the-art laboratory facilities next week – including custom freezers, where sea ice can be grown under carefully controlled conditions, and a remote-controlled submersible that can explore and sample the environment under the ice – a sense of urgency about the Arctic pervades the effort.
“It’s the part of the planet which is realizing the first and the fastest response to climate change,” says Tim Papakyriakou, one of the centre’s scientists who specializes in carbon transfer between ocean and atmosphere. “This system that we had a poor understanding of before is now changing very, very fast.”
While ice over the Arctic Ocean always grows in winter and retreats during the summer, its minimum extent, typically measured in September, is on a downward trend. Last year it hit a record low, dipping to 3.41 million square kilometres. It now looks like the Arctic will become ice free during the summer some time between 2015 and 2030.
Climate models predict a decline in sea ice as the planet warms, but nowhere near this fast. Understanding why the ice is vanishing so quickly is at the top of Dr. Barber’s agenda. Part of the answer, he says, has to do with the simple fact that water is darker than ice and absorbs more sunlight than it reflects. The more open ocean there is in the Arctic, the more solar energy is deposited there during the summer. At the onset of winter, this extra energy must be dissipated as heat before new ice can form, a process that can last well into December.
But Dr. Barber also sees a similar pattern in January and February. There is still more open ocean during those months than there was in the past, even though the High Arctic is in winter darkness during those months and excess solar energy should not be a factor.
Dr. Barber believes he has identified another influence contributing to the disappearance of the sea ice: Atlantic water entering the Arctic system via the Gulf Stream. It’s warmer and more buoyant than it used to be, which means it’s welling up under the sea ice and melting it from below.
“We’re losing more ice than we thought we were, but it’s an ocean heat source,” he says.
But converting such a sweeping change into an accurate prediction for the future also requires an intimate understanding of the sea ice at small scales. Ice that forms in different conditions of temperature and salinity, with more or less air content, will respond differently to environmental change. Biology also plays a role, as microbes colonize the ice, secreting chemicals such as sugars and also changing the amount of solar energy the ice absorbs.
“All of these things have to be taken into account,” says Nadja Steiner, a research scientist with the Department of Fisheries and Oceans, based in Sidney, B.C.Report Typo/Error