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To: cogitator
Re. your post about sea, lake and river ice. Ice freezes and thaws in cycles. This can be a win-win for you if you want to sell the notion of a warming trend. If we have a cold period with a lot of ice buildup you can talk about record amounts of ice melting when it starts to warm up again. But if we have a warm period where much of the ice has melted, then you can talk about record low ice extents even if we start to head for a cold period. Of course I’ll do just the reverse. Isn’t this fun?

The link you posted,
http://www.sciencedaily.com/releases/2000/09/000921073656.htm
talks about river and lake freeze cycles but the data he gives ends about 12 years ago. Why do you suppose no one has updated this data series? It seems like it would be an easy thing to do.

Another thing about ice is that it is supposed to create a positive feedback. Ice melts, lowering albedo and causes more melting. But Antarctic ice extents are at a thirty year high in spite of the warming over that period. Could it be that there is also a negative feedback with ice? Sea surface warms, evaporating water that becomes ice in Antarctica, increasing albedo which lowers temperature.

126 posted on 02/06/2008 10:15:46 AM PST by Dan Evans
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To: Dan Evans
This can be a win-win for you if you want to sell the notion of a warming trend.

Well, yes I do. And the data indicate a warming trend over the past 150 years, no matter how much you try to confuse the issue and avoid the question.

The data in the paper: later freeze, earlier thaw. Consistent with global warming. No other additional conflations.

Why do you suppose no one has updated this data series? It seems like it would be an easy thing to do.

Well, two things. The data set is highly variable. 12 more years might not add much information to it. Two: did you look at the first link, the authors, and the date? It's a short article; read the whole thing.

Another thing about ice is that it is supposed to create a positive feedback. Ice melts, lowering albedo and causes more melting. But Antarctic ice extents are at a thirty year high in spite of the warming over that period. Could it be that there is also a negative feedback with ice? Sea surface warms, evaporating water that becomes ice in Antarctica, increasing albedo which lowers temperature.

Did I previously provide the link to the paper by a physicist at U. Washington that shows that increasing Antarctic sea ice is a consequence of global warming. Aw, h*ll, this is so much fun I'll do it again. Don't ask me to support this one with analysis; all I can do is take his word for it.

Ach, I forgot, actually there's two of them.

Warmer Air May Cause Increased Antarctic Sea Ice Cover

Here is the information for the second, which is the one to which I was actually referring:

1) Zhang, Jinlun, 2007. Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions. Journal of Climate Vol. 20, No 11, pp. 2515–2529, June 2007

Abstract

Estimates of sea ice extent based on satellite observations show an increasing Antarctic sea ice cover from 1979 to 2004 even though in situ observations show a prevailing warming trend in both the atmosphere and the ocean. This riddle is explored here using a global multicategory thickness and enthalpy distribution sea ice model coupled to an ocean model. Forced by the NCEP–NCAR reanalysis data, the model simulates an increase of 0.20 × 1012 m3 yr−1 (1.0% yr−1) in total Antarctic sea ice volume and 0.084 × 1012 m2 yr−1 (0.6% yr−1) in sea ice extent from 1979 to 2004 when the satellite observations show an increase of 0.027 × 1012 m2 yr−1 (0.2% yr−1) in sea ice extent during the same period. The model shows that an increase in surface air temperature and downward longwave radiation results in an increase in the upper-ocean temperature and a decrease in sea ice growth, leading to a decrease in salt rejection from ice, in the upper-ocean salinity, and in the upper-ocean density. The reduced salt rejection and upper-ocean density and the enhanced thermohaline stratification tend to suppress convective overturning, leading to a decrease in the upward ocean heat transport and the ocean heat flux available to melt sea ice. The ice melting from ocean heat flux decreases faster than the ice growth does in the weakly stratified Southern Ocean, leading to an increase in the net ice production and hence an increase in ice mass. This mechanism is the main reason why the Antarctic sea ice has increased in spite of warming conditions both above and below during the period 1979–2004 and the extended period 1948–2004.

127 posted on 02/06/2008 11:31:52 AM PST by cogitator
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