The report used a combination of satellite photos and Coast Guard scanning from 1973 to 2010 to determine Great Lakes ice cover has dropped by an average of 71 per cent. Lake Ontario had the greatest loss of ice cover, while Lakes Erie and St. Clair had the least amount of ice cover loss.

Reduced ice can speed up winter evaporation and lead to lower water levels, which can then leave the shoreline exposed and more vulnerable to erosion. The loss of ice can also signal earlier algae blooms, which harm water quality and the marine habitat.

The study doesn't take the most recent winter into account, but the trend is continuing. Only about 5 per cent of the Great Lakes' surfaces froze this winter – well below the 40 per cent average.

Thunder Bay Ontario Port Authority CEO Tim Heney, said the lack of ice is remarkable. "It's the first time I ever remember the water being open right into Thunder Bay. I've never seen this before."

"What's happening on the Great Lakes is an immediate reminder that our climate is changing and the expectations that we've had in the past aren't going to hold true for the future," said Lakehead University geography professor Adam Cornwell.