A rim of ice at East Antarctica's Wilkes Basin is like a cork holding back the contents of a slanted bottle. Warming ocean could easily melt it.
"Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk,"...
The melting of a rather small ice volume on East Antarctica's shore could trigger a persistent ice discharge into the ocean, resulting in unstoppable sea-level rise for thousands of years to come. These findings are based on computer simulations of the Antarctic ice flow using improved data of the ground profile underneath the ice sheet.
"East Antarctica's Wilkes Basin is like a bottle on a slant," says lead-author Matthias Mengel, "once uncorked, it empties out." The basin is the largest region of marine ice on rocky ground in East Antarctica. Currently a rim of ice at the coast holds the ice behind in place: like a cork holding back the content of a bottle. While the air over Antarctica remains cold, warming oceans can cause ice loss on the coast. Ice melting could make this relatively small cork disappear -- once lost, this would trigger a long term sea-level rise of 300-400 centimeters.
In related news...
After interannual and multi-decadal variations were subtracted from sea level measurements, scientists found that sea level rise is accelerating.
Scientists have developed a new method for revealing how sea levels might rise around the world throughout the 21st century to address the controversial topic of whether the rate of sea level rise is currently increasing.
The study found that the most important approach to the earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual (occurring between years, or from one year to the next) to multidecadal (involving multiple decades) variability in sea level records.
"By developing a novel method that realistically approximates future sea level rise, we have been able to add new insight to the debate and show that there is substantial evidence for a significant recent acceleration in the sea level rise on a global and regional level. However, due to the large 'noise' signals at some local coastal sites, it won't be until later this decade or early next decade before the accelerations in sea level are detection at these individual tide gauge sites." [emphasis mine]
East Antarctica's Totten Glacier has likely begun irreversible melting.
The intrusion of warm ocean water is accelerating melting and thinning of Totten Glacier, which drains enough ice to raise global sea levels by 3.5 metres. The glacier is one of the major outlets for the East Antarctic Ice Sheet, which is the largest mass of ice on Earth and covers 98 percent of the continent.
Destabilisation of the Totten Glacier could leave more ice inland vulnerable to change, said Professor Siegert: "Once a certain region starts to change, the implications for the connected ice are potentially significant. ... the change at Totten Glacier itself is significant and concerning."
"It's only one glacier, but it's changing now and it is significant for sea levels globally," said study co-author Professor Martin Siegert, Co-Director of the Grantham Institute at Imperial College London. "The 3.5 metre rise may take several centuries to complete, but nowthe process has started it is likely irreversible. This is another example of how human-induced climate change could be triggering major changes with knock-on impacts that will be felt globally." [emphasis mine]
This diagram shows where sea water can penetrate under the Totten Glacier. Notice the yellow line, indicating sea level, shows us that vast areas around the very deep trough are below sea level.