Arctic Sea Ice Remains on Downward Trend

[richard schumacher]

"Despite a slight recovery in summer Arctic sea ice in 2009 from record-setting low years in 2007 and 2008, the sea ice extent remains significantly below previous years and remains on a trend leading toward ice-free Arctic summers, according to the University of Colorado at Boulder’s National Snow and Ice Data Center. (Earlier post.)"

Summary at
Green Car Congress: Despite a Slight Recovery in 2009, Arctic Sea Ice Remains on Downward Trend

The National Snow and Ice Data Center has an excellent FAQ at
Arctic Sea Ice News & Analysis: Questions about Arctic sea ice

For those who confuse ice area with ice volume: "Satellite measurements from NASA show that in 2008, Arctic sea ice was thinner than 2007, and likely reached a record low volume. In the spring of 2009, Arctic sea ice was even thinner than in 2008."

[PriusLewis]

A very good post, especially the information about sea ice volume vs coverage (volume being the real measure of interest). I've been trying to get a good friend wo is chair of the Geosciences department at Fort Hays State University to buy a Prius. His PhD disertation was on sea ice in Baffin Bay, and he keeps me up on ocean temperature and ice volume news.

[F8L]

Sea ice coverage is very important to krill recruitment though. Since krill serves as a base, or near base, for the oceanic energy web I would say coverage is equally important to volume unless we are just talking about albedo effect.

[TimBikes]

And at the other pole, sea ice area remains above normal levels. In fact, the Antarctic ice melt during the summer (October-January) of 2008-2009 was the lowest ever recorded in the satellite history.

[richard schumacher]

And again: area is not volume.

The article abstract you cite states (*emphasis mine*): "Our results suggest that *enhanced snowmelt* is likely to occur if recent positive summer SAM trends subside in conjunction with the projected recovery of stratospheric ozone levels, with subsequent impacts on ice sheet mass balance and sea level trends."

[PriusLewis]

Originally Posted by F8L

Sea ice coverage is very important to krill recruitment though. Since krill serves as a base, or near base, for the oceanic energy web I would say coverage is equally important to volume unless we are just talking about albedo effect.

True, and I hadn't considered that. And considering albedo, to some extent global warming should be self-increasing since reduced ice/snow coverage reduces albedo, thus increasing energy absorbtion (e.g., temperature). It's theorized the opposite is true: increase snow coverage and cloud coverage to a certain point and an ice age onset is self-sustaining due to increased albedo.

[TimBikes]

Originally Posted by richard schumacher

And again: area is not volume.

Yes - but your first link referenced sea ice extent - which is area, not volume.

[drees]

Originally Posted by TimBikes

Yes - but your first link referenced sea ice extent - which is area, not volume.

It references both extent and thickness. In fact, that's the whole point of the article - while surface area has rebounded well, thickness (and thus volume) is at an all time low.

Only 19% of the ice cover was more than two years old—the least ever recorded in the satellite record and far below the 1981-2000 summer average of 48%, according to the CU-Boulder report. Measurements of sea ice thickness by satellites are used to determine the age of the ice.

[TimBikes]

Originally Posted by drees

It references both extent and thickness. In fact, that's the whole point of the article - while surface area has rebounded well, thickness (and thus volume) is at an all time low.

Yes - and as surface area rebounds, it is likely thickness will as well since multi-year ice is in part a result of ice from prior years ice extent crushing together and piling up.

I guess we'll have to check back in a few years and see.