Serge Payette and Simon Thibault, two researchers at the Université Laval in Montreal, measured the retreat of the permafrost by looking for the presence of ‘palsas’, mounds of vegetation that form naturally over ice in the soil of peat bogs. During an initial survey in 2004, they examined seven bogs between the 51st and 53rd parallels. Aerial photos from 1957 showed that all seven had palsas at that time, but during the 2004 survey, that number had been reduced to two. The following year, the number of palsas in these bogs had decreased by up to 90 per cent.

While long-term climate records for the region are lacking, making it difficult to link the decline to increasing temperatures, Payette notes that the average annual temperature at northern sites that he has been studying for more than 20 years has increase by 2°C over that period.

‘If this trend keeps up, what is left of the palsas in the James Bay bogs will disappear altogether in the near future, and it’s likely that the permafrost will suffer the same fate,’ Payette said.

April 2010