Yesterday, Pakalolo posted an important diary at Daily Kos about the recently discovered acceleration in melting underneath the floating ice shelf ice sheet which supports the massive East Antarctica glacial field known as the Totten Glacier.
The findings about East Antarctica emerge from a new paper just out in Nature Geoscience by an international team of scientists representing the United States, Britain, France and Australia. They flew a number of research flights over the Totten Glacier of East Antarctica — the fastest-thinning sector of the world’s largest ice sheet — and took a variety of measurements to try to figure out the reasons behind its retreat. And the news wasn’t good: It appears that Totten, too, is losing ice because warm ocean water is getting underneath it. […]
The floating ice shelf of the Totten Glacier covers an area of 90 miles by 22 miles.
The Totten glacier already releases the most water of any glacier in Antarctica with an yearly amount of ice melt “equivalent to 100 times the volume of Sydney Harbour every year.” As Pakaloo’s diary noted yesterday NASA and the University of Texas published a study in the peer-reviewed scientific journal Nature Geoscience that “shows shows the discovery of 2 seafloor troughs that bring in warm ocean water to the base of the Totten Glacier.”
These troughs are essentially created by denser, warmer saltier water conveyed from valleys on the ocean floor to the ice shelf. The warmer water they convey is, in effect burrowing upward, thinning the ice from below and creating the risk of cracks in the ice shelf that liekly will destabilize the Totten Glacier and the large Totten Cachement area seen below (image from Pakalolo’s diary of March 16, 2015):
Should the Totten ice shelf break away or the glacier collapse, it would release enough water to raise the oceans an average of 11 feet. This risk is on top of the studies published last year that showed that melting from major ice shelves in West Antarctica has accelerated as well, and for the same reasons: “Warmer ocean waters are pushing up from below and bathing the base of the ice sheet.” The rate of melting of those ice shelves in West Antarctica has dramatically accelerated over the last twenty-three years.
The researchers found that the [West Antarctica] ice sheet contributed about 4.5 millimeters, or 0.18 inches, to global sea-level rise from 1992 to 2013, with more than 70 percent of the loss occurring in the second half of that time period — meaning the rate of loss is accelerating. […]
“We now show that the ocean is the major contributor of heat” to West Antarctica, said lead study author and oceanographer Sunke Schmidtko of the University of East Anglia in Britain. “And it’s not just the shelf itself — it’s something that happens offshore in the global ocean.”
This could ultimately prove to be one of the most important geophysical processes on the planet, for the simple reason that the ice sheet of West Antarctica would, if it collapsed entirely, contribute about 3.3 meters, or nearly 11 feet, to global sea-level rise, Alley said.
Ironically, the potential 11 feet rise from melting of the West Antarctica ice shelves is the same amount predicted should the Totten Glacier collapse. And this is not just a pie in the sky prediction anymore. Large cracks in the Larsen-C Ice Shelf in West Antarctica have already been observed (image from Pakalolo’s diary of March 9, 2015):
The same process, a warming ocean in the Southern Hemisphere, is not only generating ice loss and the threat of ice shelf collapse in West Antarctica, but it is also having the same effect on a major floating ice shelf in East Antarctica.
In its alignment with the land and the sea, the Totten Glacier is similar to the West Antarctic glaciers, which also feature ice shelves that slope out from the vast sheet of ice on land and extend into the water. These ice shelves are a key source of instability, because if ocean waters beneath them warm, they can lose ice rapidly, allowing the ice sheet behind them to flow more quickly into the sea. […]
The availability of warm water, and the observed melting, notes the study, “support the idea that the behaviour of Totten Glacier is an East Antarctic analogue to ocean-driven retreat underway in the West Antarctic Ice Sheet (WAIS). The global sea level potential of 3.5 m flowing through Totten Glacier alone is of similar magnitude to the entire probable contribution of the WAIS.”
Even more troubling is that the rate of sea ice melt is more rapid than expected and is clearly linked to climate change. We can’t predict exactly how soon these unstable ice sheets will detach from the mainland of Antarctica, but the fact that evidence of their thinning and cracking should give all of us pause for great concern.
As one scientist who reviewed the studies of the West Antarctica ice shelves noted:
“For long-term stability and small sea-level rise, accelerating mass loss is not reassuring,” said Pennsylvania State University glaciologist Richard Alley, commenting on the paper, which was published Tuesday in Geophysical Research Letters. […]
“There are strong reasons to believe that if the thinning goes too far, it might cross a threshold and then accelerate much more rapidly,” he said.
I think it is safe to say that with the further discovery of the same process at work in East Antarctica with respect to the Totten Glacier and Totten Cachement, that threshold is likely to be crossed sooner than anyone expected, even those in the scientific community who have been conducting this research.
Unfortunately this news that getting little traction in traditional media for reasons that are all to familiar to those of us who pay attention to the issue of climate change and its ongoing consequences, both those occurring now, such as the category five cyclone that devastated the island nation of Vanuatu in the Pacific, to the severe and long-lasting drought on our own West Coast that has brought California to the point where its reservoirs have only one year’s worth of supply left in them..
I know that outrage over the absurd and dangerous actions of Republicans such as Senator Tom Cotton and his fellow travelers are the red meat of that brings eyeballs to this site, but Climate Change is literally the most significant event of the 21st Century. It is the one overriding issue that most threatens human civilization and the mass extinction of species, all of whose fates are interconnected with our own. Its effects, from wars to famines to droughts to floods to mega-storms, etc., are already happening before our eyes in real time. Those effects will only worsen as sea levels rise as melting of the Greenland and Antarctic ice sheets accelerates.
The national and local media ignore the problem, and conservative websites sites and “news outlets” deny and mock these stories. So if we don’t do what’s necessary to call attention to the impacts of climate change, present and future, who will?
