Ellesmere island is about 800km (500 miles) from the North Pole
It is said to be the largest break in 25 years, casting an ice floe with an area of 66 sq km (25 square miles).
It occurred in August 2005 but was only recently detected on satellite images.
The chunk of ice bigger than Manhattan could wreak havoc if it moves into oil drilling regions and shipping lanes next summer, scientists warned.
For something that large to move that quickly is quite amazing
Luke Copland, University of Ottawa
"The Arctic is all frozen up for the winter and it's stuck in the sea ice about 50km (30 miles) off the coast," said Luke Copland, an assistant professor at the University of Ottawa.
"The risk is that next summer, as that sea ice melts, this large ice island can then move itself around off the coast and one potential path for it is to make its way westward toward the Beaufort Sea where there is lots of oil and gas exploration, oil rigs and shipping."
'Quite amazing'
The ice break was initially undetected due to the remoteness of the northern coast of Ellesmere island, which is about 800km (500 miles) from the North Pole.
Satellite images showed the 15km (9mile) crack, then the ice floating about 1km (0.6 miles) from the coast within about an hour, said Mr Copland, a specialist in glaciers and ice masses.
"You could stand at one edge and not see the other side, and for something that large to move that quickly is quite amazing," he said.
Mr Copland said a combination of low accumulations of sea ice around the edges of the ice mass, as well as the Arctic's warmest temperatures on record, contributed to the break.
The region was 3C (5.4F) above average in the summer of 2005, he said.
Ice shelves in Canada's far north have shrunk by as much as 90% since 1906.
"It's hard to tie one event to climate change, but when you look at the longer-term trend, the bigger picture, we've lost a lot of ice shelves on northern Ellesmere in the past century.
"This is that continuing and this is the biggest one in the last 25 years," he said.
The Ayles ice shelf, which is more than 11,000 football fields in size and is located just south of the North Pole, has broken free in the Canadian Arctic. Scientists say that global warming has played a "major" role in the break.

The entire 41 square miles of the shelf broke away from Ellesmere Island at least 16 months ago, and the break was discovered when a satellite took pictures of the region recently.

"This is a dramatic and disturbing event. It shows that we are losing remarkable features of the Canadian North that have been in place for many thousands of years. We are crossing climate thresholds, and these may signal the onset of accelerated change ahead," said Warwick Vincent, a Laval University scientist who studies conditions in the Arctic.

Higher temperatures are believed to have played a significant role in the break, and all 6 shelves in the Canadian Arctic have become at least 90% smaller since they were discovered in the early 1900's.

"It the break is consistent with climate change. We aren't able to connect all of the dots, but unusually warm temperatures definitely played a major role," added Vincent.

Seismographs detected the break and collapse of the shelf in August of 2005. The short amount of time it took for the event to occur has come as a surprise to scientists.

"What surprised us was how quickly it happened. Even 10 years ago scientists assumed that when global warming changes occur that it would happen gradually, so that perhaps we expected these ice shelves just to melt away quite slowly. It's pretty alarming," said head of the University of Ottawa's global ice lab, Luke Copland.