Thawing permafrost is a growing problem for the Iqaluit airport, especially as the airport is about to undergo major renovations.

Permafrost researchers have produced a map that shows where climate change could most affect Iqaluit. It shows most parts of the city are on stable ground, but one area of concern is the Iqaluit airport.

On a recent tour, airport manager John Hawkins pointed to damage on the runway apron caused by asphalt sinking into melting permafrost. It had to be replaced by a concrete slab.

On the taxi way, another stretch of pavement was ripped out and replaced by gravel that can be re-graded as the ground shifts. That means aircraft which aren't certified to move over gravel have to take a longer way around.

"We do want to have an exit off each end of the runway and right now, we have one that's limited to certain aircraft," said Hawkins.

Michel Allard began studying permafrost in Iqaluit in 2010. He produced the map which shows the surface geology in Iqaluit, and it pays special attention to the airport.

"The airport is built on a network of ice wedges and also, over the years, some small ponds and lakes have been covered, and the land has been reshaped quite a lot," said Allard.

Allard studied old aerial photographs to find where waterways were buried under the aiport. He says the waterways are in the exact same spots where weaknesses are found now.

"The layer that thaws every summer now gets deeper because of climate warming, so it affects the buried ice masses in the ground, and when they melt the ground collapses on top."

Allard and his team will return next month with specialized drilling equipment to take ice core samples at the airport to back up their data.

For now, Hawkins isn't too worried about the runway or its safety. He says maintenance crews are watching the runway every day.

"Really, I have a high level of confidence in it. Until it changes, then we can get on it pretty quickly."

Hawkins says the timing is good: the tender is out for a new terminal and other upgrades which could cost up to $300 million. But first, he wants to make sure they understand exactly what they're building on.