August ARCUS forecast poll – What will the September NSIDC Arctic minimum extent be?

Dave Springer says:
July 28, 2011 at 8:43 am
(trimmed)
Albedo at the pole is essentially insignificant compared to the difference between having sea ice blocking everything except conductive heat loss or not. The sun is too low in the sky most of the time in the Arctic for there to be a great difference in albedo between water and ice. Water albedo increases as the angle of incidence increases.
Ice or no ice is like the difference between having an igloo or not. It’s also why sled dogs bury themselves in snow to keep warm while they sleep. Might be counter-intuitive for some but a house made of ice will keep you warmer than no house at all. Once the ocean surface is exposed to air it can give up heat one helluva lot faster than when it’s covered with ice. So what we have is a negative feedback situation where as Arctic sea ice cover declines the earth’s capacity to vent heat to space rises. Works just like clouds. Fewer clouds allows more energy to reach the ocean which raises the evaporation rate which produces more clouds which then block energy from reaching the ocean surface. Negative feedbacks are way cool. The only positive feedback we need to worry about is snow and ice cover reaching into lower latitudes and persisting longer. That’s a positive feedback situation that’ll lead to a snowball earth if nothing stops it.
Ah, so you have anticipated one of Hansen’s much-feared “tipping points” of climate catastrohope-and-fear” ..
Float a perfectly flat square meter of ice in the ocean on the Equator on any clear day between Mar 22 and Sept 22, and it is easy to calculate how much heat energy is absorbed into the ice, and how much is reflected back up into the sky.
Let the ice melt – which it will quickly do – and try again.
It is obvious that – at the Equator between March 22 and Sept 22 – a perfectly flat and calm square meter of open “pure” ocean water under perfectly clear skies will receive much more heat energy through the day than it radiates into space. Thus, the water will heat up, will expand, will evaporate more as well. It will heat the air above the water, outgoing IR radiation will even warm the CO2 molecules above that square meter of water. There is a very real, very much positive, sea ice albedo temperature feedback.
At the equator. Under clear skies with low, puff-ball clouds and high humidity. There. Only there. At that location near the equator there is a positive sea ice albedo feedback. (No sea ice of course. But a nice large positive albedo feedback from sea ice melting that is easy to calculate.)
Now, let us move that same experiment a little bit north. Repeat the same experiment for one meter of sea water at 80 north.
At what latitude, and at what real-world times of the year will a single square meter of open Arctic sea water receive so little heat energy from the sun that it must freeze? Phrased differently, at what latitude will you find that a nice white blanket of sea ice insulates that meter of sea water from the freezing air, lowers heat radiation into the Arctic night, and traps ocean heat by preventing evaporation such that any open water cools the Arctic air?
Do we not have much to fear from an open Arctic Ocean …. because that open Arctic Ocean will lead to the colder temperatures in the far north?

Tim Folkerts says:
July 29, 2011 at 6:27 am

“Worse – the DMI HAS measured the temperatures at 80 north latitude every day since 1958. And Arctic summer temperatures have consistently gone down since that date. Why does Hansen claim his +4 degree rise?”
A couple problems with this meme have already been pointed out. Let me add some more.
1) Summer temperatures have inconsistently gone down, with a fair amount of variation. An eyeball estimate is that there has been 0.2 – 0.3 C decrease in summer melt season temperatures.

You make my point: Summer temperatures at 80 north have been measurably decreasing since 1958. In particular, measured summertime temperatures at 80 North have begun decreasing faster the more that measured sea ice extents have reduced.
Further, during that entire period that summertime high Arctic temperatures have been decreasing, CO2 levels worldwide, and, thus supposedly also in the Arctic, have been measurably increasing.
Yet, the CO2 CAGW effect is (theoretically at least) required to be highest in the summertime Arctic since (1) solar summertime exposure is highest there the greatest number of hours per day, and 2) the low temperatures mean that water vapor pressure is very low. Thus, the effect of CO2 should be maximized … just where it is measured at being not only not at its maximum, but measured temperatures have been decreasing the faster as measured CO2 rises.

2) Summer air temperatures never vary much anyway. The sea surface is going to remain right around 0 C, and the air is only ~ 1 C above that. Anyone who has looked at the graphs will see that summer temperatures will not change much

Measured temperatures have not exhibited much of a decrease to be sure, but the decrease is NOT the +4 degree C increase that Hansen-GISS claims in the NASA red plots across the Mercator projection of the Arctic tundra down in Canada.

3) You are conflating (I will assume accidentally) summer temperatures with annual temperatures. Even the DMI data shows a large increase (~ 2 C) over the past few decades in the annual average temperature, which is surely what Hansen was talking about. To compare Hansen estimates for annual change with DMI estimates for summer change is worse than meaningless.
(And so far this year, the DMI temperatures have once again been way above average.)

Wrong. DMI temperatures this summer have remained within 1/2 degree of the “average” – which is itself weighted by the previous 50 years of “higher” temperatures. That is NOT “way above average”.
We are discussing ONLY summertime temperatures because “summer” in the high Arctic is the only time of year that the sun is visible, and, to keep on the subject of sea ice extents and a supposed positive-melting-sea-ice-albedo-feedback, you need sunlight as a prerequisite.
No sunlight, no albedo feedback, true? Therefore, for this problem, winter temperatures are meaningless. The average of summertime high-latitude Arctic temperatures – the ONLY ones of interest when the sun is shining at latitude 80 north – and winter temperatures extrapolated during the dark for 63 north is meaningless. And Hansen knows this. But he can’t find his feedback, nor his high Arctic temperatures unless he goes thousands of kilometers south across the Canadian tundra and then extrapolates sideways between widely-spaced stations.