Arctic ice shelf crumbles in heat

Much of Canada’s last remaining intact ice shelf has broken apart into hulking iceberg islands thanks to a hot summer and global warming, scientists say.

The 4000-year-old Milne Ice Shelf on the northwestern edge of Ellesmere Island had been Canada’s last intact ice shelf until the end of July, when ice analyst Adrienne White of the Canadian Ice Service noticed that satellite photos showed that about 43 per cent of it had broken off. She said the break happened around July 30 or 31.

Two giant icebergs formed, along with lots of smaller ones, and they had already started drifting away, White said.

The biggest is nearly the size of Manhattan – 55 square kilometres and 11.5km long. The icebergs are 70 to 80 metres thick.

‘‘This is a huge, huge block of ice,’’ White said. ‘‘If one of these is moving toward an oil rig, there’s nothing you can really do aside from move your oil rig.’’

The undulating ice shelf of ridges and troughs dotted with blue meltwater used to measure 187 sq km – larger than the District of Columbia – but now is down to 106 sq km.

Temperatures from May to early August in the region had been 5 degrees C warmer than the 1980 to 2010 average, University of Ottawa glaciology professor Luke Copland said. This was on top of an Arctic that already had been warming much faster than the rest of the planet, with the Ellesmere Island region warming even faster.

‘‘Without a doubt, it’s climate change,’’ Copland said, noting that the ice shelf was melting from both hotter air above and warmer water below.

Canada used to have a large continuous ice shelf across the northern coast of Ellesmere Island in the Canadian territory of Nunavut. It had been breaking apart over the last few decades because of man-made global warming, White said. By 2005, it was down to six remaining ice shelves but ‘‘the Milne was really the last complete ice shelf’’, she said.

‘‘There aren’t very many ice shelves around the Arctic any more,’’ Copland said. ‘‘It seems we’ve lost pretty much all of them from northern Greenland and the Russian Arctic. There may be a few in a few protected fjords.’’

Record heat and fires have also melted ice

in Siberia this northern summer.

Researchers from the National Snow and Ice Data Centre in the US fear that the Arctic ice caps, which lack the bulk that allows larger glaciers to stay cold, could disappear by 2022.