Saturday 24 August 2019

'Glaciers are melting into the sea faster than predicted'

Ice warning: A team studied the surface melting of a glacier in Alaska
Ice warning: A team studied the surface melting of a glacier in Alaska

Nina Massey

Glaciers could be melting underwater at a faster rate than previously thought, new research suggests.

Scientists have developed a method to directly measure the submarine melt rate of a tidewater glacier.

Their results suggest current theoretical models may be massively underestimating glacial melt.

Previously direct melting measurements have been made on ice shelves in Antarctica by boring through to the ice-ocean interface beneath.

But where there are vertical-face glaciers that end at the ocean, those techniques are not possible.

University of Oregon oceanographer Dave Sutherland said: "Tidewater glaciers are always calving and moving very rapidly, and you don't want to take a boat up there too closely."

A team of scientists led by Mr Sutherland studied the subsurface melting of the LeConte Glacier, which flows into LeConte Bay south of Juneau, Alaska.

The findings are published in the journal 'Science'.

In the past, research on the underwater melting of glaciers has mainly relied on theoretical modelling, measuring conditions near the glaciers and then applying theory to predict melt rates.

But the theory has rarely been tested.

The team deployed a multi-beam sonar to scan the glacier's ocean-ice interface from a fishing vessel six times in August 2016 and five times in May 2017.

Co-author Rebecca Jackson, an oceanographer at Rutgers University-New Brunswick, said: "We measured both the ocean properties in front of the glacier and the melt rates, and we found that they are not related in the way we expected.

"These two sets of measurements show that melt rates are significantly, sometimes up to a factor of 100, higher than existing theory would predict."

Irish Independent

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