Robert Fanny (aka ‘Robertscribbler) takes time off scribbling about electric cars to say something about climate change
Rapid Sea Level Rise Possible as Ocean Floods into Antarctica at up to 400 Meters Per Year
4
April, 2018
From
west to east and in a growing number of places, a
warming ocean is cutting its way deep into Antarctica.
Grounding lines — the bases upon which mile-high glaciers come to
rest as they meet the water — are in rapid retreat. And this ocean,
heated by human fossil fuel burning, is beginning to flood chasms
that tunnel for hundreds of miles beneath great mountains of ice.
Such
an immense flood has the effect of speeding up glaciers as
far away as 500 miles from the point of invasion.
It does this by generating a kind of abyssal pit that the glacier
more swiftly falls into. And as these watery pits widen, they risk
pumping sea level rise to catastrophic levels of ten feet or more by
the end of this Century.
(A
new study in Nature is the first to survey the rate of grounding line
movement around Antarctica’s entire perimeter. What it found was
disturbing. A large number of major glaciers are seeing historically
rapid rates of grounding line retreat [red arrows] as only a few
glaciers show very slow rates of grounding line advance [blue
arrows]. Image source: Hannes Konrad et al, Nature,
University of Leeds.)
The
great ocean invasion is clearly on the march. Not yet proceeding
everywhere, the advance is happening in enough places to cause major
worry. In West Antarctica, 22
percent of its glaciers are seeing their grounding lines move
inland by
more than 25 meters per year. In the Antarctic Peninsula, 10 percent
of glaciers are experiencing this retreat. And in East Antarctica,
where the ice is piled thickest, 3 percent of glaciers are affected
by the swift invasion.
The
most rapid retreat — at up to 400 meters per year — is presently
happening at Thwaites
Glacier in
West Antarctica. Thwaites alone encompasses enough ice to lift the
world’s oceans by 3 meters. And the rate of inland ocean water
invasion at this single location is a very serious concern.
(Grounding
line retreat is just one of many factors that increase the risk of
rapid sea level rise. Ice cliff instability, increased rainfall over
glaciers, large floods of water into glaciers from melt ponds that
then refreeze and fracture the ice, and a number of other factors all
compound as the Earth is heated up by fossil fuel burning. Video
source: International
Business Times.)
But
the issue is not one of single glaciers. It’s one where many very
large mounds of ice all around Antarctica are under threat. And in
much the same way that a dike risks breaking apart when it is punched
through by a growing number of holes, Antarctica’s own flood gates
to rapid sea level rise are threatened by each grounding line in
quickening retreat. Another such ‘hole’ has formed at the Totten
Glacier where
the grounding line is retreating at around 150 to 175 meters per
year. And Totten could produce another 3.4 meters of sea level rise
if it collapsed into the Southern Ocean.
Continuing
the dike anology, Antarctica holds back enough water as ice, in
total, to lift the world’s ocean levels by an average of 200 feet.
By greater or lesser degrees, each retreating glacier contains a
portion of the potentially massive flood. And the overall rate of
loss in the form of new glaciers going into retreat together with the
pace of inland ocean invasion is speeding up.
This
new set of research provides
a more complete if fearsome picture of Antarctic melt. And though
models aren’t yet able to pinpoint how fast sea level rise will be,
a growing body of evidence points to greater than previously expected
risk for rapid sea level rise this Century. So for the sake of our
coastlines and of so many cities around the world, the time to act as
swiftly as possible to reduce carbon emissions and their terrible
related impacts is now.
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