Researchers have gained unique insight into the mechanisms behind the collapse of Antarctic ice shelves, which are crucial for sea level rise in the Northern Hemisphere.

The discovery of old aerial photos has provided an unparalleled dataset that can improve predictions of sea level rise and how we should prioritize coastal protection and other forms of climate adaptation.

On 28 November 1966, an American airplane flies over the Antarctic Peninsula just south of the southernmost tip of Chile.

On board is a photographer, probably from the US Navy, whose job is to map the Antarctic landscape. But it turns out that the photographer is also documenting a very special situation that is in progress. He shoots an aerial photo of the Wordie Ice Shelf, which, 30 years later, has almost vanished after a total collapse.

The consequence of this collapse was that the “plug” that held large amounts of glacier ice broke off, leaving the ice sheet floating freely into the sea.

Fortunately, Wordie is a relatively small ice shelf and the sea level rise it has caused can be measured in millimeters. But there are much larger ice shelves in Antarctica, which, like Wordie, could collapse due to climate change. Just the two largest ice shelves, Ronne and Ross, are believed to hold enough ice to account for sea level rises of up to five meters.

If, in this context, we think that Antarctica is far away, we need to understand that the melting of ice in the Southern Hemisphere will cause sea levels to rise in places like Denmark in the Northern Hemisphere, due to the effects of gravity. A new research study provides insights that can help identify signs of incipient collapse in these ice shelves and assess the stage of collapse.

The photo of Wordie from 28 November 1966—the first in a long series of images that continually document the collapse of the Wordie Ice Shelf through the 1960s—has become a valuable first data point in a study of the ice shelf collapse recently completed by researchers at the University of Copenhagen.

Read the full article about old photos improving sea level rise predictions at Futurity.