Unglacial speed of ice melting should be call to action
By Frances LambertsThe connotation of the word “glacial” as meaning infinite slowness in movement or action no longer holds.
The host of NPR’s Science Friday radio show recently, surprised at the “unbelievable pace” at which Antarctic ice sheets are moving sea ward, wondered if “the world’s biggest ice cube” is melting.
A scientist studying the glaciers there confirmed the pace of some to be such, a foot an hour, that their movement is directly observable.
Through warmer ocean waters lubricating the ice masses from below, surface melt water sinking through cracks and crevasses “hydrofracturing” them, the giant ice shelves are disintegrating.
Glaciers that took thousands of years to form these shelves, he said, are accelerating and adding water to sea levels globally.
Were all of this “ice cube” to melt, numerous islands and coastal cities would be drowned, worldwide.
During the interglacial period that preceded the last ice age, as science writer Elizabeth Kolbert has documented, sea levels were at least fifteen feet higher than they are today.
By one theory regarding climate system dynamics, this was due to collapse of the Antarctic ice sheet.
Another relates it to melting of the other of the planet’s two ice sheets, in Greenland.
Nearly four times the size of France, Greenland’s ice sheet holds enough water ro raise sea levels by twenty-three feet.
As Kolbert’s book Field Notes from a Catastrophe describes, researchers have been studying Greenland’s ice for nearly three decades.
The compressed layers hold “snow that fell when the cave painters at Lascaux were slaughtering bison” and snow from a 100,000 years ago.
Their trapped air bubbles chronicle pollution — lead from ancient Roman smelters and nuclear fallout from early atomic tests, for instance — when, “much like the rings of a tree,” each yearly layer was formed.
Their composition also allows determination of how cold it was then.
The earth’s temperature record preserved in the ice reveals climate change to not necessarily occur “only glacially” but to be capable of unpredictable and quite sudden disruptions and reversals.
The Greenland the ice sheet has been thinning by around 50 feet annually since the early 1990s.
Some of its glaciers’ speed-of-glide to the sea, 13 inches per day in 1996, increased to nearly twice that in 2001.
On July 16, an iceberg twice the size of Manhattan was calved from one of the major glaciers.
It followed another, twice that size and among the largest ever recorded, in 2010.
Now, on July 24, “stunned” NASA scientists report a sudden, wholly extraordinary amount of ice loss.
The data from three independent satellites show that “in less than a week, the amount of thawed ice surface skyrocketed from 40 percent to 97 percent, [reaching] nearly all of Greenland’s ice cover.”
The melting of Greenland’s glaciers is among tipping points that the climate scientists have warned we must avoid if we would preserve a livable planet.
High time for a tipping point — away from denial and inaction — in the country’s politicsregarding climate change.