There's an upside to the extreme cold temperatures northern Canadians have endured in the last few weeks: scientists say it's been helping winter sea ice grow across the Arctic, where the ice shrank to record-low levels last year.

Temperatures have stayed well in the -30s C and -40s C range since late January throughout the North, with the mercury dipping past -50 C in some areas.

Satellite images are showing that the cold spell is helping the sea ice expand in coverage by about 2 million square kilometres, compared to the average winter coverage in the previous three years.

"It's nice to know that the ice is recovering," Josefino Comiso, a senior research scientist with the Cryospheric Sciences Branch of NASA's Goddard Space Flight Centre in Maryland, told CBC News on Thursday.

"That means that maybe the perennial ice would not go down as low as last year."

Canadian scientists are also noticing growing ice coverage in most areas of the Arctic, including the southern Davis Strait and the Beaufort Sea.

"Clearly, we're seeing the ice coverage rebound back to more near normal coverage for this time of year," said Gilles Langis, a senior ice forecaster with the Canadian Ice Service in Ottawa.

Winter sea ice could keep expanding

The cold is also making the ice thicker in some areas, compared to recorded thicknesses last year, Lagnis added.

"The ice is about 10 to 20 centimetres thicker than last year, so that's a significant increase," he said.

If temperatures remain cold this winter, Langis said winter sea ice coverage will continue to expand.

But he added that it's too soon to say what impact this winter will have on the Arctic summer sea ice, which reached its lowest coverage ever recorded in the summer of 2007.

That was because the thick multi-year ice pack that survives a summer melt has been decreasing in recent years, as well as moving further south. Langis said the ice pack is currently located about 130 kilometres from the Mackenzie Delta, about half the distance from where it was last year.

The polar regions are a concern to climate specialists studying global warming, since those regions are expected to feel the impact of climate change sooner and to a greater extent than other areas.

Sea ice in the Arctic helps keep those regions cool by reflecting sunlight that might otherwise be absorbed by darker ocean or land surfaces.