Wednesday, August 20, 2008
Sea ice watch: There is still more than last year
Notwithstanding widespread and repeated predictions that the sea ice in the Northern Hemisphere would melt catastrophically this year, there is actually more of it than there was last year. This page contains a nifty engine that allows you to compare Northern Hemispheric sea ice on any two dates since 1980. Compare, for example, the sea ice area on August 18, 2008 with the same date last year.
I have not seen a convincing argument accessible to laymen that explains why we should worry only about the melting Arctic sea ice in particular. As this graph shows, aggregate sea ice area was above the baseline level as recently as early 2008, so there is no evidence of any global anomoly (or if there is it is beyond my understanding). If the concern is that melting sea ice will reduce the planet's albedo (reflectivity) which will drive even more warming, then one would think that it would be the global sea ice area that would matter.
A couple of weeks ago I discussed this subject in a post linking to an article by Bruce Lieberman, who writes for the Yale Forum on Climate Change and the Media. Lieberman had cited a scientist who worried about melting Arctic sea ice because of the reduction in albedo, so I sent him (Lieberman) an email asking why albedo was not a function of global sea ice area (which has shown no reduction below the long-term average). Lieberman promised to put the question to the scientist quoted in the article and get back to me, but I have received no response notwithstanding follow up emails. Too bad, because it would seem to be an important point. [CORRECTION: I heard from Mr. Lieberman in December 2008, and apparently he had sent me a response during the summer that got hung up along the way (perhaps in my company's aggressive spam filter). See the response here.]
5 Comments:
By 
, at
Wed Aug 20, 06:40:00 AM:
Back when I worked in remote sensing, I spent some time modeling the Earth's albedo - nothing fancy, but enough for my purposes. So I think I can answer your question regarding why you aren't getting a response: either that scientist or Lieberman doesn't knwo what they are talking about.
First, to the extent polar ice -- to include sea ice -- affects albedo, the total area does matter; the Arctic sea ice is in no way preferred. But polar ice has a weak effect on albedo compared to it's area because it's near the poles; it's effective area is greatly reduced.
The Earth's albedo is primarily a function of cloud cover. One would have to wonder if warming caused the Arctic sea ice to melt if this might not also cause more evaporation leading to more clouds and an overall higher albedo resulting in more reflected sunlight and hence lower temperatures. That of course is the kind of simplistic negative feedback the AGW true believers sneer at.
Curt Johnson
By 
JPMcT, at
Wed Aug 20, 06:51:00 AM:
One wonders what the defining fact will be that finally snaps us out of the AGW dream. The hysteria has died down, but not completely. We still have lawmakers in various countries, and the U.N., making apocalyptic statements defining our doom if we do not change our distribution of power and wealth...and DO IT NOW! Perhaps they "feel the heat" of emerging common sense.
It is sad that those who make their living in Science, and those who should have been properly educated to understand it (i.e., the rest of us)allowed this preposterous notion to emerge with the relative impact that it hads had. Sad.
By , at
Wed Aug 20, 10:13:00 AM:
But polar ice has a weak effect on albedo compared to it's area because it's near the poles; it's effective area is greatly reduced.
Just stop right there Curt. Rationality has no place in this discussion!
By , at
Wed Aug 20, 12:16:00 PM:
http://www.natice.noaa.gov/ims/
Thumbnail on the left side of the screen allows access to latest still shots or a java movie of the last 31 days of ice status in the polar region.
By , at
Wed Aug 20, 04:20:00 PM:
2008 is way below the recent average ice cover. Anyone who thinks that anything short of a new record low is always good news is mistaken.
Re albedo: 1. the 2007 Antarctic high was an anomaly but the overall long-term declining Arctic trend isn't. 2. Local effects matter - Arctic has feedbacks, particularly methane release from melting permafrost, that can't be made up for in the Antarctic.
