Climate change

Arctic buoy photo shows 'melt pond', not drastic sign of global warming

PUBLISHED : Wednesday, 31 July, 2013, 12:00am
UPDATED : Wednesday, 31 July, 2013, 3:40am

Alarming images of a scientific observation buoy floating in what appeared to be an Arctic lake near the North Pole lit up the online world in the past week, sparking questions about whether this was a sign of global warming. Now, the scientist who installed the buoy has given a succinct answer: no.

Also, the buoy was never quite at the North Pole, oceanographer James Morison said. Its most recent location is about 480 kilometres away. After about a week of being surrounded by water, the buoy sat on top of a frozen sea on Monday, just as it had earlier this summer.

That's just part of summer ice conditions, and as far as we know it always has been

The water the buoy was bobbing in last week was not a lake, but a melt pond, a common occurrence in the Arctic summer when the sun shines 24 hours a day, said Morison, principal oceanographer for the North Pole Environmental Observatory, funded by the US National Science Foundation.

While the air temperature hovers around freezing point, solar radiation works to melt snow and the upper layer of sea ice. Some of the water drains through cracks down into the Arctic Ocean and the rest forms freshwater ponds on top of the sea ice with their surfaces slightly above sea level. "That's just part of summer ice conditions, and as far as we know it always has been," Morison said.

Morison said he experienced melt ponds when he stayed in an Arctic ice camp. "Melt ponds become part of your life," he said. "They build little plywood bridges over the melt ponds, your footwear changes completely from giant sock-like mukluks to hip waders and it's really miserable."

This particular pond grew roughly to about the size of an Olympic swimming pool, with a width of up to 50 metres, and a depth of perhaps 60 centimetres. Below the pond was a layer of ice more than a metre thick, Morison said from the Applied Physics Laboratory at the University of Washington in Seattle.

Morison and his team installed the scientific observing buoy in April, about 40 kilometres from the North Pole. The buoy did what it was supposed to do, drifting away with the Arctic sea ice to help scientists track what the ice was doing. Last year, Arctic sea ice cover dropped to its lowest summer level, according to the US Snow and Ice Data Centre.

Report: Reuters Photos: AP