Up till now, we basically had a stationary [East Antarctic] ice sheet, and now it’s started to move,” -- Catherine Walker, NASA post-doctoral fellow.
East Antarctica. Home to most of the world's remaining land ice. Scientists previously thought that this last bastion of somewhat stable ice in the world would only slowly succumb to the slings and arrows of human-caused climate change. That its ice giants would still sleep for some time -- giving the world more time to stave off or avoid worsening rates of sea level rise. Unfortunately, new evidence reveals that this is not the case. That the best time to act on sea level rise was 20+ years ago, and that the second best time to act, in cutting fossil fuel based CO2 emissions, is now.
(Warm water upwelling near East Antarctica's Totten Glacier threatens to accelerate global sea level rise. Image source: Texas Institute for Geophysics.)
Extreme warming now periodically besets this frozen land. Massive ice bergs are breaking off from West Antarctica, rainfall is now observed, at times, all around the frozen continent's perimeter from west to east, and the vast Pine Island glacier is being undermined by warm water currents -- causing it to crack up from the inside out.
Now, according to new research, one of East Antarctica's largest glaciers -- the Totten -- is accelerating toward the Southern Ocean. It's a situation that we warned about in an earlier post as an indicator of worsening risks of speeding sea level rise due to human caused climate change. Unfortunately, new studies by scientists have now confirmed that warm waters encroaching on Totten have already had an impact.
Researchers found that combined warm winds and encroaching warmer ocean currents had caused the glacier to speed up by 5 percent during the period of 2000 to 2006. This acceleration means that the vast glacier -- home to enough ice to raise seas by 11-13 feet -- is melting faster. It also means that the glacier is starting to succumb to the tremendous global heat forcing provided by human fossil fuel burning around the world. We should caution that this report covers a period from more than a decade ago. And since that time, human-forced global warming has considerably advanced.
(The Totten Glacier itself contains enough ice to raise seas by 11-13 feet, which is comparable to all of West Antarctica. Its glacial catchment, however, is larger. Image source: Australian Antarctic Division.)
The primary cause of Totten's melt acceleration is wind-diven warm ocean currents starting to encroach upon the glacier. These warm currents dive deep and then upwell near the glacier faces and along their weak underbellies. What the new research shows is that CO2-based warming from fossil fuel emissions is increasing the heat content of the waters even as it drives the strengthening of winds that bring these waters into more frequent direct contact with glaciers like Totten.
Chad Greene, one of the study's lead authors recently noted to Scientific American:
"Upwelling is driven not purely by the broad-scale magnitude of wind, but by the gradient in wind—how strong the wind is at one latitude versus how strong it is at a different latitude. And CO2 in the atmosphere is modeled to increase the wind gradient around Antarctica, and then therefore increase upwelling around Antarctica."
Glaciers are very difficult to move when sitting still. But once they get moving, it's very difficult to stop what amounts to a moving mountain of ice. Forces now encroaching upon Antarctica are now conspiring to trigger the seaward movement of various gigantic glaciers. Once that happens, a certain amount of sea level rise gets locked in. This new research indicates that Greenland and West Antarctica aren't the only systems that are capable of seeing glaciers released in this fashion. With the new research from Totten, East Antarctica is starting to come into play as well. And that means that multi-meter sea level rise this Century is not out of the question.
Hat tip to Colorado Bob