Michael Tobis wrote:
I basically agree with Chris and leaving aside transaction costs and risks
I'd trade at 60 cents or perhaps a tiny bit higher.
From an NCAR CCSM mailing list I'm on:
==>
Marika Holland, Cecilia Bitz, and Bruno Tremblay's 2006 AGU paper
titled "Future Abrupt Reductions in the Summer Arctic Sea Ice" has been
getting quite a bit of attention in the media. This study use the
future climate scenario runs of the CCSM3 to predict changes in Arctic
sea ice.
The full paper is available here:
http://www.agu.org/journals/gl/gl0623/2006GL028024/
A short video highlight from Marika's presentation is available here:
http://zdnet.com.com/1606-2-6142733.html
A BBC News Article is available here:
http://news.bbc.co.uk/2/hi/science/nature/6171053.stm
As any Montrealer (or anyone who has lived in a cold and snowy climate) can
attest, seasonal ice certainly behaves that way. As spring approaches the
snowpack begins to soften up and melt around the edges, but most of the
energy goes into warming the interior of the pack. Once the whole mass has
reached a temperature near enough to freezing, all it takes is a mild spell
to abruptly remove the bulk of the frozen water.
Paleoclimatic evidence also shows that ice is an amplifier of temperature
trends.
As a modeler I would be alarmed if it behaved otherwise. The ice warms up
gradually and vanishes suddenly. That is what real ice does, so I would
expect that would be what modeled ice does.
After Holland's paper was published, I went back over several issues
that I have previously had disagrement with regarding sea-ice models.
I also ran thru some of the SHEBA data to find an answer to my old
complaints.
As some may recall, I have noted that some early GCM models did not
include zenith angle adjustment for ocean albedo. Indeed, looking at
the documentation for the CCSM 3 model from NCAR, I noticed that they
use a constant albedo of 0.06 with no adjustment for zenith angle.
While this value may be appropriate for the oceans at lower latitudes,
the Arctic is different. At the North Pole, the zenith angle is never
less than 66.5 degrees, which happens only at the summer solsice. As
one moves away from the North Pole, the zenith angle exposure may be
greater, but then there is a diurnal cycle as well, so the daily
average albedo would be impacted.
Measurements taken in a tower study published way back in 1972 indicate
that the albedo can be much larger than the 0.06 incorporated in the
CCSM 3. This would likely be true for the direct component of the
insolation in the Arctic, while the diffuse component would be expected
to be close to the 0.06 value. Given that the weather over the Arctic
sea-ice is frequently cloudy, the diffuse value may dominate. I
exchanged e-mails with Dr. Holland and she agreed with me that it would
be better to include a more realistic albedo model based on zenith
angle. She also suggested that this will be incorporated into the
model in future.
Thus, I think it's a bit premature to use these latest model results as
an accurate forecast of the date certain of total loss of sea-ice at
the end of the summer melt. It may be worth repeating the suggestion
that the sea-ice is melting from below, perhaps the result of an
increasing inflow of warm waters from the Pacific and Atlantic.
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