Polar ice cap absorbs greenhouse gases

Scientists on board the Amundsen ice-breaker get surprising findings

By JANE GEORGE

One year into its mission to understand more about the impact of climate change in the Arctic, the Amundsen is back in Quebec City.

The travelling research vessel returned to port with a load of new and puzzling information for scientists to mull over during the coming months.

Researchers who wintered on board the Amundsen were astonished to observe that Arctic winter sea ice apparently sucks carbon dioxide – one of the greenhouse gases responsible for global warming – out of the atmosphere and sends it down into the frigid water.

“This transfer could slow down global warming, so that’s an important observation. But it surprised us – in fact, we were taken totally off guard,” says Louis Fortier, the lead scientist on the $100-million-dollar ArcticNet study on climate change.

Cod like the cold
Last winter, researchers based on the ice-bound ship also studied how Arctic cod – the most numerous of all Arctic fish species – spend the coldest months of the year. Again, much to their surprise, they detected huge schools of cod eating away at plankton near the bottom of the underwater Continental Shelf.

“We thought they would be in hibernation, but they were very active, despite the fact that the temperature was -1.8 C in the salty water and it’s totally dark,” Fortier says.

By munching on plankton, these cod also help digest and process carbon dioxide – so perhaps the fish also play a role in keeping global warming in check.

“But not nearly enough,” Fortier adds.

The continuing retreat of sea ice cover will eventually affect the Arctic cod. As warmer waters move into the Arctic, more southern species of cod or other fish will follow, as has already been observed along Alaskan coasts where Pacific salmon are now found, or, even closer to home, in Hudson Bay, where the winter ice season has become much shorter during the past 30 years.

Fortier says thick-billed murres in Hudson Bay used to eat only Arctic cod, but now their diet is comprised of 50 per cent capelin – a sign that the marine environment there is changing.

“We see the diet of birds is changing. So, things are changing, and the cod is starting to be replaced by other species because the ice is withdrawing,” Fortier says.

The result? Fortier says this progressive ice retreat and changeover in species will transform the Arctic Ocean as we know it today into a kind of “outlet” of the Atlantic and Pacific oceans – and this could happen fairly quickly.

“The change is rapid from a geological and ecological viewpoint, but I think we will really see significant signs of change by 2080 or the end of the century. We won’t see it, but our children will see it,” Fortier says.

As the Amundsen sailed through the Arctic waters, researchers also installed six underwater observation boxes armed with instruments to measure temperature, salinity, currents, ice thickness and the amount of algae.

“We also put in microphones to listen to marine mammals, seals and whales. The idea is to see how many there are and what their activity is. We hope to get a general idea of the underwater noise levels before intercontinental traffic increases,” Fortier says.

Next year, the Amundsen plans to install similar underwater monitoring stations between Ellesmere Island and Greenland and in Hudson Bay.

A seabed map for ships
As it travelled through the Northwest Passage, the Amundsen also used sonar radar to map its bottom.

“There are places that are very shallow, so if the transcontinental traffic of boats increases we will have to know where to go. Mapping had been done, but not at the levels we’re going,” Fortier says.

Mapping is also important, he says, for overall planning when the Northwest Passage turns into an ice-free route.

“It will allow us to plan what will happen, to anticipate what is in store over the next 100 years, to better prepare strategies and policies to lessen the impacts on the environment and maximize the positive impacts for residents,” Fortier says.

In the Beaufort Sea, the Amundsen’s team also noted a huge underwater landfall at the edge of the underwater continental shelf, that’s created a long canyon.

“We don’t know when it happened. Maybe it happened 10,000 years ago, maybe 100 years ago,” Fortier says.

The collapse could mean that the seabed is unstable – an important concern for any future offshore oil installations.

Next year, the Amundsen will continue its travels, most likely in the Foxe Basin.

ArcticNet’s mission is likely to continue through 2010 and be extended again for another seven years so researchers can track changes as warming progresses and be in a better position to protect people and animals from the most catastrophic impacts.

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