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August 07 2012

21:17

Arctic Ice Decline Much Worse Than Expected

As the extent of Arctic sea ice declines to levels unrecorded since satellite monitoring began, the National Snow and Ice Data Center has released a new analysis that shows the situation to be worse by far than even the most pessimistic models predicted.

It's a perverse endorsement of one of the most popular denier memes - that you can't rely on climate models because the world is too complicated to be reduced to a compilation of computer data. But, thanks to the expertise (and conservative nature) of the scientists behind this work, the models have shown the direction with perfect accuracy: it's the terrifying extent that they have failed to anticipate.

In addition to the catastrophic conditions currently prevailing in the Arctic, the NSIDC has also drawn attention to the dramatic melting occurring this year in Greenland. And all this is supported and reinforced by the Polar Science Center's ongoing calculation of Arctic ice volume.

The trends are all down. Or as James Hansen put it in the Washington Post last week, "Climate change is here - and it's worse than we thought."

January 18 2011

19:32

Arctic Sea Ice Still at Lowest Extent Ever

The usual concern for Arctic sea ice crops up in the summertime, when the frightening ice decline results in more open water, and therefore a greater capacity for the dark Arctic Ocean to absorb the 24-hour sun's heat - rather than reflect it back into space, as was the case when most of the Arctic surface was covered with bright, white ice.

But look at the state of Arctic ice now. Even as we approach the usual winter maximum, the ice extent is lower than at any time in recorded history, according to the National Snow and Ice Data Center in Boulder, Colorado. The Polar Science Center in Seattle reports that ice volume also continues its decline, or should I say, collapse - at unprecedented speed, to unprecedented lows.

Thus, despite the calls from d'oh-headed deniers like Art Horn for a global chill driven by a "super La Nina," we have a year that wraps up tied as the warmest ever and a continuing trend that indicates the coming summer will feature the effects of redoubling climate feedbacks.

We stand in awe of the DenierGang's ability to tie themselves up in logical knots and we await their next falacious analysis with unfailing interest.<!--break-->

November 03 2010

17:16

Arctic Sea Ice Trends: Down, Down Down

Two graphs, inluding the brand new one to the left, show two (mutually affirming) analyses of the trajectory of Arctic sea ice over the last 30 years.

The National Snow and Ice Data Center graph (left) shows Average Monthly Sea Ice Extent. The figure below shows a Polar Science Center model-generated calculation of Sea Ice Volume. Notwithstanding that NSIDC reports Arctic temperatures in October were 4 to 6 degrees Celsius (7 to 10 degrees Fahrenheit) higher than normal, there is something chilling in the similarity of the two graphs. 

PIOMAS Ice Volume Anomaly<!--break-->

September 23 2010

23:55

Arctic Ice: There's bad news and worse news

Arctic Sea Ice Extent, which the National Snow and Ice Data Center (NSIDC) in Boulder, Co., announced had reached its annual minimum on Sept. 10, has now slipped even further, to a point that could be below the 2008 minimum. That would make this the second lowest summer ice cover in recorded history.

"It's awfully close (to the 2008 low)," NSIDC research scientist Dr. Walt Meier said on Wednesday (Sept. 22, 2010). "And even though the air temperatures are getting colder, the ocean has a lot of heat in it and can continue to melt ice."

Meier acknowledged that the NSIDC jumped the gun in announcing the apparent annual minimum. The ice extent had been increasing for three consecutive days and the scientists assumed the season had turned. But much of the ice is broken up and thin, conditions that mean "it doesn't take a lot to get late season melting," Meier said.

Ice watchers may be more concerned, however, by the inset Polar Science Center graph of ice volume, which shows that the total amount of ice (as differentiated from the extent of the Arctic ice cover) has dropped off a cliff.

<!--break-->The Arctic Sea Ice Volume Anomaly illustrated in this figure is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed by Dr. J. Zhang and collaborators at the University of Washington. It suggests a precipitous decline, including eight consecutive years when the ice volume has dropped sharply down even from the declining trend line.

The problem, as the scientists at NSIDC have been saying for years, is that old, thick, multi-year ice has been melting and getting replaced by young, thin ice. The total amount of ice is therefore diminishing to a degree that is not fully revealed by the declining ice extent.

Dr. Meier says quite willingly that neither measure is fully satisfactory. The NSIDC ice extent measure is more directly reliable, in that it is the result of observation rather than modeling. But the satellite data still needs to be interpreted and the NSIDC test - that any particular quadrant has at least 15% ice cover - is difficult to calculate exactly.

The NSIDC uses the 15% number because "that seems to correspond most closely to the actual ice edge," Meier says. But in a quadrant that is 25 kilometres square, that could mean there is dispersed ice floating over the whole area or one solid chunk filling up 15% in one corner of the quandrant. The dispersed ice might appear to cover a larger area, but it would also be more vulnerable to melting from the warm ocean than would ice in one consolidated piece.

As for the PIOMAS Arctic Sea Ice Volume Anomaly, it has been widely validated, most obviously against the NASA ICESat Satellite data, but it still derives from a mathematical model, a fact that will always attract criticism from a denier community that either doesn't understand modeling, doesn't want to, or both.

Nevertheless, even assuming big margins of error (the Polar Science Center graph shows one and two standard deviations), Arctic ice is in a period of extensive and consistent decline. And given that melting ice sets up a positive feedback loop - with the dark ocean now absorbing radiative energy that was once reflected by white ice - this promises to create more trouble. And unless you are inclined to completely ignore or cavalierly misrepresent the evidence, that you cannot deny.

June 30 2010

21:43

Contemplating Arctic sea ice collapse

Wondering whether weather indicates climate

The latest graph tracking un unprecedented plunge in Arctic sea ice measurements raises once again the question of when you can look at a weather event - a dramatic and unprecedented weather event - and make a relevant and reasonable assumption about what is happening to the climate.

Given the enthusiasm that the denier community brings to challenging assumptions at the contestable edge of science, I'd be wary about saying, unequivally, that this graph shows climate change in action. It's only part of one year's data. Admittedly, it's compared to an average over a much longer time, but it's still just one year. That's why you might want to look at the next graph:<!--break-->

Average Monthly Arctic Sea Ice Extent 1979-2010

There's a trend line, clear as day. Now, ideologically blinded polemicists like Lawrence Solomon may be able to look at a single month's data and decide that trends are unhelpful by comparison - especially when that single month seems to make his point. But anyone who chooses to be both thoughtful and honest - and to bring even a touch of scientific rigor to his or her considerations - is going to look at these longer time-series graphs and say: you know, that looks like climate. In fact, that looks like climate CHANGE.

Given the obvious domination of ideologues in power (in Canada, at least), this also can be interpreted to suggest that we're all in a lot of trouble. But hey, on the eve of Canada day, let's join the deniers - for for 24 carefree hours - and pretend. I'm sure it will be fun, and the ice really won't care whether we miss it or not - just for a day.

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