This is a follow-up to the post on global
that I posted earlier
prompted me to look into the issue a little more. There is a comment
at Huffington Post
, but it is not
very informative...or at least it wasn't until j7uy5 added a
substantive comment earlier today. I've expanded on that here.
Greg cited an article in Science (abstract
by Ola M. Johannessen et. al.
, that shows that the
thickness of the ice cap is increasing, at least in the areas of
greatest elevation. The abstract, however, is not very
informative. The authors were interviewed by reporters, and
some additional detail is available on CNN, here
The CNN article includes information from some other
[...] And the scientists said that the thickening of
the ice-cap might be offset by a melting of glaciers around the fringes
of Greenland. [...]
"Ice sheets now appear to be contributing modestly to sea level rise
because warming has increased mass loss from coastal areas more than
warming has increased mass gain from enhanced snowfall in cold central
regions," it said.
"Greenland presently makes the largest contribution to sea level rise,"
according to the report by scientists led by Richard Alley of
Pennsylvania State University in the United States.
Similarly, the authors of the paper cited by The Independent
interviewed elsewhere. An
published by TerraDaily, with the lead author,
Ian Howat (a UCSC doctoral candidate in Earth Sciences), and his
, includes the following:
Satellite images dating back as far as the 1970s show
that the front of
the glacier has remained in the same place for decades.
But in 2001 it began retreating rapidly, moving back four and a half
between 2001 and 2005. Howat's measurements also show that the Helheim
glacier has sped up from around 70 feet per day to nearly 110 feet per
and thinned by more than 130 feet since 2001.
As the glacier speeds up and retreats, new factors come into play that
cause further acceleration and retreat, Howat said. "This is a very
glacier, and it's likely to get faster," he said. [...] "Outlet
may have been thinning for over a decade," Howat said. "But it's only
the last few years that thinning reached a critical point and began
drastically changing the glacier's dynamics. [...] "Our research
strong evidence that rapid melting processes such as we observed at the
Helheim glacier will play a role in ice sheet reduction, but they are
currently not included in the models." Tulaczyk said.
Us non-geophysicists* can't really assess the science in all the papers
written on the subject. Even if we could, it would not be
valid to cite just a few papers and pretend that we have a
comprehensive understanding of the subject. As perpetual
sophomores, however, we are free to read a subset of the relevant
literature and say what we think.
here would indicate that the melting around the edges of the ice cap is
more significant than the thickening of the top. That
certainly is what Howat, Tulaczyk and Alley believe. Since
they undoubtedly have already read the Johannessen paper, and have
taken it into account, I tend to think they are correct.
However, we really need to wait until the Howat paper appears
in print, and the experts have a chance to mull it over.
After all, that is how science works. People
publish their stuff, and everyone else tries to pick it apart.
If it survives, it becomes the latest version of the truth.
* Usage note: "non-geophysicist" sounds better than "non-earth
scientist," and is not ambiguous.