Did the melting Arctic ice shelf break up once before?

Researchers think one Canadian ice shelf broke up 1,400 years ago and then re-froze

Images of the Arctic ice shelf cracking up are an icon of the damage wrought by global warming.



But a team of researchers from the Universite Laval in Canada have found evidence that one ice shelf might have broken up before, 1,400 years ago – long before industrialisation had any impact on the planet.



A study of sedimentary material on the bottom of Disraeli Fjord in Canada, found evidence of what the team described as a ‘major fracturing event’ 1,400 years ago.

Scientists believe the Ward Hunt ice shelf north of Ellesmere Island, Nunavut, Canada, broke up and then re-froze 800 years ago

They believe at least one ice shelf, Ward Hunt north of Ellesmere Island, Nunavut, Canada, the largest remaining ice shelf in the Arctic at 170 square miles, broke up and then re-froze 800 years ago.



Ice shelves are thick platforms of ice which have been pushed out to see by the pressure from glaciers.

They act as dams in fjords and result in sediment building up at the boundary between fresh water from the ice and salt water from the ocean.

Researchers used carbon dating and other techniques to examine the sediment and were able to create a timeline of events.



They found the ice shelf appeared 4,000 years ago staying whole for several thousand years before fracturing 1,400 years ago. They said it didn't fully re-freeze until 800 years ago.



Melting: A chunk of ice is shown drifting after it separated from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada's far north in 2008

It began to shrink again almost 100 years ago and is getting smaller every year.



Dermot Antoniadesa said: 'At this point, it doesn’t appear that the shelf ice around Ellesmere Island is any smaller now than it was during the previous period of warming, but because it’s still shrinking, it’s possible it could become, an 'unprecedented' event.'

The team published the results of their survey in the Proceedings of the National Academy of Sciences.

