Arctic coastlines are on the retreat, especially in Canada, and their disappearance has significant implications for both the ecosystem and the economic and social life of the North, according to a group of international researchers.

The changes are particularly dramatic in the Beaufort Sea along the coast of the Northwest Territories, Yukon and Alaska, and in the Laptev and East Siberian Seas, along Russia's north coast. Some sections have seen erosion rates reach more than eight metres a year as protective sea ice along the coast disappears.

The study found that on average, the Arctic coastline is retreating by half a metre a year.

"Every single element of the North is going to be affected, right from the engineering side to how the Inuit interact with their environment," Wayne Pollard, a McGill University geomorphologist who contributed to the study, told The Canadian Press.

The 2010 study, by a consortium of more than 30 scientists from 10 countries, was released Sunday in the journal Estuaries and Coasts. The consortium includes researchers from the German-based Alfred Wegener Institute for Polar and Marine Research.

The project examined more than 100,000 kilometres of shoreline, or a quarter of all Arctic coasts. It's the first to compare different rates of erosion as well as consider its impact on northern people.

Increasing erosion

While they can't prove it because they have limited year-over-year data to work with, scientists suspect that gradual washing-away along thousands of kilometres of northern shoreline is speeding up.

The researchers say rising temperatures in the North due to climate change are causing coastal sea ice to disappear, leaving coasts unprotected against the eroding force of waves. The problem is especially acute in the Arctic because about two-thirds of its coast is made up of permafrost, which is much softer and therefore more susceptible to erosion than rock.

The researchers say that since roughly a third of the world's coasts are located in the Arctic permafrost, coastal erosion may affect enormous areas in future.

That's a concern for Arctic river deltas along the coast, which have high biodiversity and are extremely productive in relation to other parts of the Arctic. The researchers worry these productive areas may change as the coast erodes.

Pollard, who works extensively among the Inuvialuit of the N.W.T.'s Mackenzie Delta region, said the changes are already affecting traditional practices such as hunting seals, polar bears and beluga whales. People so attuned to their local environment that they can navigate in fog by the currents affecting their boats can no longer count on the old assumptions, he said.

"There's going to be shoals where there weren't shoals before, there's going to be storms coming from different directions," he said. "It's really starting to disrupt the traditional knowledge."