NASA’s Operation IceBridge, an airborne survey of Earth’s ice at both poles, has confirmed the presence of a deep subsurface rift in the Antarctic ice shelf that could indicate it is melting much more quickly than previously thought.
Such rifts have been seen in the Greenland Ice Sheet, but this is the first detected in Antarctica, where rifts typically form at ice sheets’ weakened ends rather than inland.
If additional inland rifts open up and spread out from the center of glaciers to their edges, the West Antarctic Ice Sheet could break up quickly, causing significant increases in global sea level.
Operation Ice Bridge conducts flights over Earth’s polar regions to survey their ice levels. The current rift, located in the Pine Island Glacier ice shelf, was first seen on November 4, 2016, after scientists studying satellite images of the area discovered the feature by chance.
“It’s generally accepted that it’s no longer a question of whether the West Antarctic Ice Sheet will melt; it’s a question of when.” said Ian Howat of Ohio State University.
“This kind of rifting behavior provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see a significant collapse of West Antarctica in our lifetimes.”
Airplane flyovers and field studies are needed to better understand how such rifts form, as satellite data from space is limited in the information it can provide, he added.
Current levels of Antarctic sea ice are the lowest ever for this time of year since NASA started satellite imaging in 1979.
Expanded this year, Operation IceBridge flew numerous flights over the Bellinghausen Sea, observing a vast area of the continent over six weeks.
A crack observed in Antarctica’s Larsen C ice shelf is more than 70 miles long, over 300 feet wide, and approximately a third of a mile deep.
IceBridge project scientist Nathan Kurtz, a sea ice researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said when flying over the Bellinghausen Sea, researchers saw open water in areas typically covered by ice.
The rift in the Pine Island Glacier occurred because something weakened the ice shelf’s center, most likely the melting of a deep crack at the bedrock level caused by a warming ocean.
Howat published his findings in the journal Geophysical Research Letters.
If all Antarctic ice melted, global sea level would rise over 200 feet.