A seven square kilometre section of Greenland’s Jakobshavn Isbrae glacier broke up between July 6 and 7. The chunk of lost ice is roughly one-eighth the size of Manhattan Island, New York.

The calving front — where the ice sheet meets the ocean — retreated nearly 1.5 km in one day and is now further inland than at any time previously observed.

Scientists estimate that as much as 10 percent of all ice lost from Greenland comes through Jakobshavn. It is also believed to be the single largest contributor to sea level rise in the northern hemisphere, said a NASA statement.

Scientists led by Ian Howat of the Ohio State University and Paul Morin, director of the Antarctic Geospatial Information Centre, University of Minnesota have been monitoring satellite images for changes in the Greenland ice sheet.

While this week’s breakup itself is not unusual, Howat noted, detecting it within hours and at such fine detail is a new phenomenon for scientists.

The breakup “lends credence to the theory that warming of the oceans is responsible for the ice loss observed throughout Greenland and Antarctica”, said Thomas Wagner, cryospheric programme scientist at NASA Headquarters.

The researchers relied on imagery from several satellites, including Landsat, Terra, and Aqua, to get a broad view of ice changes at both poles.

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