Huge Cracks in Antarctic Glacier Foreshadow Epic Calving Event

The European Space Agency (ESA) released a video this past week showing the evolution of two very large and disconcerting cracks in Antarctica’s Pine Island Glacier. They have each grown to 20km in length and could shear off a hunk of ice the size of Paris and Manhattan combined.

The Pine Island Glacier—located at the base of the Antarctic Peninsula on the western side of the continent—has always shipped Antarctic ice out to sea at prolific levels, but it’s become famous in recent years due to its ever increasing output. These new cracks are just the latest development in a flurry of epic calving events at Pine Island. These used to occur about every six years but are now happening on an almost yearly basis.

The ESA compiled images of the cracks taken by one of their two polar orbiting Sentinel-1 satellites to make the video. Sentinel-1 is continuously monitoring land, sea, and sea ice conditions with a synthetic-aperture radar instrument that allows it to take pictures in all weather conditions and even at night—a key feature in high latitudes, which experience long periods of darkness in the winter months.  These satellites are part of ESA’s larger Copernicus mission.

Pine Island Glacier feeds into a floating body of ice called an ice shelf. A recent study published in Science Advances this month revealed that these ice shelves, and Pine Island Glacier  in particular, are experiencing accelerated melting from underneath, as a combination of fast moving and buoyant plumes of warm water carve troughs into their bottom surface. This makes the shelves more prone to large calving events and ultimately to shrinkage and retreat.

Pine Island Glacier is made of ice from the West Antarctic ice sheet and flows into the Amundsen Sea. (Credit: NASA)

“Warm water circulation is attacking the undersides of these ice shelves at their most vulnerable points,” said lead earth scientist and lead author of the report, Karen Alley. “These effects matter,” she added. “But exactly how much, we don’t yet know. We need to.”

The large calving event building at Pine Island Glacier also comes at a period of particular concern for melting glaciers around the world. The International Panel on Climate Change released its special report on the state of the Earth’s cryosphere last month in which it predicted continued warming of ocean waters and increasing mass loss of the Antarctic Ice Sheets—of which Pine Island Glacier is a part—throughout the 21st century.

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