A chunk of ice twice the size of Manhattan has broken off Greenland in the last two years

This section of the northeast Greenland ice shelf has disintegrated over the last two years.

(CNN)A 44-square-mile chunk of ice, about twice the size of Manhattan, has broken off the Arctic's largest remaining ice shelf in northeast Greenland in the last two years, leaving scientists fearful over its rapid disintegration.

The territory's ice sheet is the second biggest in the world behind Antarctica's, and its annual melt contributes more than a millimeter rise to sea levels every year.
"We should be very concerned about what appears to be progressive disintegration at the Arctic's largest remaining ice shelf, because upstream ... is the only major Greenland ice sheet ice stream," said Jason Box from The Geological Survey of Denmark and Greenland (GEUS) in a statement on Monday.
    "These last two summers have been exceptionally warm," Box said, speaking to CNN Monday.
    "The [recent] ice that has broken off is just under ... twice the size of Manhattan. [The disintegration] has really picked up these last couple of years."
    The GEUS researchers have been tracking the loss of ice in the area, using optical satellite imagery.
    Greenland, the world's largest island, is located between the Arctic and Atlantic oceans and around 79% of its surface is covered in ice.
    The section marked in red at the top of this optical satellite image shows the ice lost from the Nioghalvfjerdsfjorden glacier.
    As ice near the Earth's poles melts, sea levels are projected to rise by more than three feet by the end of the century, wiping away beaches and coastal properties.
    Since 1999, the Greenland shelf has lost 62 square miles of ice, according to GEUS.