UCI, NASA JPL scientists uncover additional threat to Antarctica's floating ice shelves - Mirage News

27, 2021 – Glaciologists at the University of California, Irvine and NASA’s Jet Propulsion Laboratory have examined the dynamics underlying the calving of the Delaware-sized iceberg A68 from Antarctica’s Larsen C ice shelf in July 2017, finding the likely cause to be a thinning of ice melange, a slushy concoction of windblown snow, iceberg debris and frozen seawater that normally works to heal rifts.

In a paper published today in Proceedings of the National Academy of Sciences, the researchers report that their modeling studies showed melange thinning to be a major driver of ice shelf collapse.

They selected 11 top-to-bottom cracks for in-depth study, modeling to see which of three scenarios rendered them most likely to break: if the ice shelf thinned because of melting, if the ice melange grew thinner, or if both the ice shelf and the melange thinned.

Instead, the model showed that a thinning ice shelf without any changes to the melange worked to heal the rifts, with average annual widening rates dropping from 79 to 22 meters (259 to 72 feet).

“When the melange is only 10 or 15 meters thick, it’s akin to water, and the ice shelf rifts are released and start to crack.”.

Even in winter, warmer ocean water can reach the melange from below because rifts extend through the entire depth of an ice shelf.