Over the past two decades, we have been hearing about the ice in Antarctica thinning, but recent studies are showing that its edges have been melting at a 70% faster rate over the last decade. “We are starting to lose more ice at a faster rate; we’re accelerating,” says Helen Fricker, a climate scientist at University of California, San Diego’s Scripps Institution of Oceanography.
These ice-shelves floating on the water act as door-stoppers keeping land-based ice sheets or glaciers from flowing to the sea. If these stoppers vanish within decades, the massive rivers of ice would then terminate in the oceans, raising sea levels drastically.
Antarctica’s ice, all melted could raise sea levels by more than 200 feet. That, of course, will not happen in a day, or even in a year or a decade–it would take hundreds to thousands of years. But the recent studies indicate that Antarctica in contributing more and more to the rise in sea levels and the pace is accelerating.
The new estimate is based on satellite measurements of the ice taken over an 18-year-period. Briefer snapshots of the ice had missed the overall trend, partly because the same sheet may shift and grow, back and forth, from year to year, says Fricker’s co-author, Fernando Paolo, a geophysics PhD candidate at UC San Diego’s Scripps Institution of Oceanography and lead author of the study published online Thursday in the journal Science.
That is on the western side, but what on the eastern side that contains more ice than the west?
The satellite data in the new study showed that for the first part of the study period, East Antarctic glaciers gained mass overall, then came to a halt during the second half of the time period. However, considering individual glaciers, some have still been gaining mass, but others, like Totten, have lost mass.
The reason behind the difference between the east and west of Antarctica is mostly because the distinct geology of each.
The glaciers on the Antarctic formed by the accumulation of snowfall flows downhill toward the sea. In the east, these ice masses are mostly “grounded” to land, so changes in these ice-sheets are driven largely by the changes in snowfall. Those glaciers however have protrusions floating on the sea, and studies have shown these “floating” extensions are thinning as rapidly as those in the west.
In the west, most of the ice sheet is marine, and grounded to the continent below sea level. Warmer waters coming into contact with that boundary, or grounding line, are thinning it from the bottom and making the grounding line retreating inwards. In the many areas of western Antarctica where ice sheets lie on a bed where the inland slope is downward, the retreat of the grounding line could trigger massive acceleration of land glaciers, according to the study.
The new study, which is based on analysis if satellite data from 1994-2012, said shelves in the Bellingshausen and Amundsen seas had the most rapid thinning, losing an average of 24 to 63 feet per decade. The most drastic loss was recorded on the Venable ice shelf (thinned by an average of 118 feet per decade) on the Bellingshausen Sea, according to the study. The Crosson shelf on the Amundsen Sea could go the same way, as per the study. If the rate stayed the same, they could disappear in 100 years.
Those rates are conservative “lower bound” estimates, said Paolo.