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Temperatures
over Greenland Fast Approaching 400,000 Year High, Risk 15-19 Feet of
Additional Sea Level Rise
26
June, 2014
It’s
getting hot over Greenland. Not the kind of hot we think of as each
summer rolls along. But the kind of hot that melts massive
two-mile-high slabs of ice. How hot? Within a decade or two,
Greenland temps could reach their highest levels in at least 400,000
years. And that’s a problem. A big fracking problem.
Why?
Because
a mere 1 degree Celsius of warming separates Greenland from
temperatures last seen during the warmest interglacial of the last
million years. During that time, sea levels were 6-13 meters higher
than today — a staggering 19-44 feet. Melt came from both West
Antarctica and Greenland, but until this week we didn’t know what
melt portion came from which glacier system. For a
study published Wednesday in Nature has pinned down the extent of the
Greenland ice sheet of 400,000 years ago.
And this new knowledge gave researchers the ability to estimate
Greenland’s contribution to the swelling seas of that time.
The
study took sediment cores from regions surrounding Greenland and, in
doing so, was able to establish that enough ice melted from Greenland
during a time when ice sheet temperatures were just 1 degree Celsius
warmer than today to raise sea levels by between 4.5 and 6 meters (15
to 19 feet).
(The southern tip of Greenland, as seen in this June 26, 2014 LANCE MODIS satellite shot, was ground zero for a major ice melt during a warm interglacial period 400,000 years ago when Greenland was just 1 degree C hotter than it is today. Melt likely first issued from the low-lying and ocean exposed glaciers along the west coast of Greenland adjacent to Baffin Bay. Today, this region hosts Greenland’s fastest glaciers as well as its most extensive proliferation of surface melt ponds.)
A
large portion of this ice came from the very vulnerable southern tip
of Greenland. According to the ice core measures, two mile high ice
mountains flooded away under the Arctic heat of 400,000 years ago,
retreating to a meager central dome separated from a northern ice
sheet which was also greatly reduced. In total, about two thirds of
the ice from greater Greenland was lost (total loss of the Greenland
ice sheet would raise sea levels by 24 feet).
Study
co-author Anders Carlson noted
in a recent press release —
“…the threshold for ice sheet collapse is pretty low. We could be
nearing the tipping point.”
Staring
Rapid Greenland Melt in the Face
One
degree Celsius, that’s all that separates all of the southern
Greenland ice and a portion of the rest from a likely irreversible
slide into the world ocean. And that’s also a rather pressing
problem. Because the Arctic is now warming faster than anywhere else
on Earth, at least two times faster than the global average. But for
Greenland the recent pace of warming has been even faster. For
since 1979 the surface of the Greenland ice sheet has warmed by 1
degree Celsius every decade.
This
gives us just one more decade under the current pace of Greenland
warming before we hit a threshold in which 15 to 19 feet of
additional sea level rise is locked in and added to the already
locked-in losses of about 4 feet from West Antarctica and about 5
feet from the other permanently destabilized and irreversibly
collapsing glaciers and ice caps around the world.
That
may just be the start. For the current CO2e forcing of 481 ppm is
sufficient, if maintained long-term, to melt enough ice to raise sea
levels by at least 75 feet overall. Unfortunately, ghg levels aren’t
anywhere near stabilizing, but are instead rising faster than ever
before. So rapidly that we hit levels high enough to all the ice on
Earth within 23 years. It’s a vicious threat to the world’s
coastal communities. One that is difficult to overstate.
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