The rapid and possibly irreversible change affecting the Arctic will have a profound impact on Northern Ireland, according to the World Wildlife Fund.
The report showed climate change was happening now
The warning comes in a new report prepared for the eight nations which surround the region.
The Arctic Climate Impact Assessment said ocean ice could have disappeared in summers in 50 years time.
Malachy Campbell from the World Wildlife Fund in Northern Ireland said "the big melt has begun".
"That is bad news for all of us," he said.
"Increasing melting of glaciers and the Greenland ice sheet could weaken or even stop the warm flow of the Gulf Stream.
"This would have catastrophic consequences for Britain and Ireland which would then experience severe freezing winters, like those in Canada. This report should act as a real wake up call for us. We need to act.
"Life on earth would change beyond recognition with the loss of the ice sheet at the north pole and higher sea levels threatening cities such as London, New York and closer to home Derry and Belfast as well as other coastal communities."
He said the report showed climate change was happening now and would have serious impacts for everyone on the planet.
"It is imperative that Northern Ireland develops a long-term energy strategy, which incorporates reducing energy consumption and a 'switch' from fossil fuels to increasing use of renewable resources," he said.