San Diego Union-Tribune (Sunday)
ICE SHELF BIGGER THAN NYC BREAKS OFF ANTARCTICA’S EAST
Experts say loss happened sooner than expected
An ice shelf larger than New York City has broken off eastern Antarctica, the first major shelf to collapse there in more than four decades of satellite observations.
The Conger Ice Shelf, spanning about 460 square miles, shattered off the continent on March 15. Its disintegration has alarmed scientists, who have long considered ice in eastern Antarctica as relatively stable and far less vulnerable to global warming compared to ice in western Antarctica.
Ice shelves surrounding Antarctica protect ice sheets and glaciers on the continent. If the shelves give way, it creates a path for ice streams from surrounding glaciers to spill into the ocean and contribute to sea level rise. The ice shelves themselves do not directly lift the sea level because they’re already floating on the ocean.
In just the last three weeks, sea ice levels surrounding the continent dropped to a record low and temperatures on the interior of eastern Antarctica shot up 70 degrees above normal, smashing records.
“We’re seeing these things sooner than we expected,” said Peter Neff, assistant research professor at the University of Minnesota and an expert in glaciology.
Ice loss from Antarctica has accelerated in recent years — much of which comes from western Antarctica — and ranks as a significant driver of global sea level rise. What happens in eastern Antarctica is particularly important because if all of its ice were to melt, it would raise sea levels by well over 100 feet.
The collapse of the Conger Ice Shelf occurred at the beginning of the recordbreaking warm spell in eastern Antarctica. On March 18, temperatures rose 50 to 90 degrees above normal over parts of the East Antarctic Ice Sheet and rain, a rare occurrence on the continent, fell near the coast.
Temperatures near where the ice shelf broke off began rising above the melting point right around the time it separated from the continent. A weather station in Casey, Antarctica, about 186 miles from the Conger Ice Shelf had maximum temperatures above freezing from March 15-18.
Neff said the pulse of warmth, transported over the continent by an usually intense plume of moisture known as an atmospheric river, probably played a relatively small role in the ice shelf ’s collapse. But it may have contributed to its disintegration, he added.
The record low sea ice levels surrounding Antarctica probably played a bigger role in hastening the ice shelf ’s demise, Neff said. He described the ice shelf ’s demise as a wake-up call for scientists studying the region.
“We expect the ice shelves on the west to be doing this but not the eastern ones,” he said in a phone interview. “That’s what got folks’ attention. We really need to be more comprehensively tracking all of these processes in east Antarctica. Small mistakes in eastern Antarctica can lead to big oversights.”