Regions of Arctic tundra around the world are heating up very rapidly, releasing more greenhouse gases than predicted and boosting the process of global warming, according to a leading expert.
Prof. Greg Henry of the University of British Columbia also said higher temperatures meant larger plants were starting to spread across the tundra, which is usually covered by small shrubs, grasses and lichen. The thicker plant cover means the region is getting darker and absorbing more heat.
He said tundra covers about 15 per cent of the world's surface and makes up around 30 per cent of Canadian territory.
Prof. Henry, who has been working in the Arctic since the early 1980s, said he had measured "a very substantial change" in the tundra over the last three decades, citing greater emissions and plant growth.
Since 1970, he said, temperatures in the tundra region had risen by 1 degree Celsius per decade - equal to the highest rates of warming found anywhere on the planet.
"We're finding that the tundra is actually giving off a lot more nitrous oxide and methane than anyone had thought before," Henry told reporters on a conference call from Resolute in the northern Canadian territory of Nunavut.
"We're really trying to get a handle on this because if (further tests show) that's true, this actually changes the entire greenhouse gas budget for the North, and that has global implications," he said.
Scientists blame climate change on a surge in emissions of greenhouse gases. The effects in Canada's North and Arctic regions have been particularly notable.
Prof. Henry said his research station in Nunavut had recorded record high temperatures virtually every summer since the early 1990s. The warmer temperatures mean plants are growing bigger and faster, while larger species are spreading northward.
"The tundra is getting a lot weedier all the way around the globe. This has major implications," said Prof. Henry, who also chairs an international project studying tundra.
"You're changing the colour of the surface of the earth by making it darker... so the consequence of that is increased warming again."
Some scientists also fear that as the permafrost in the Arctic melts, it will release vast amounts of carbon and methane into the atmosphere.