An update on Jeff Id's excellent sea ice video

“Counterintuitively, as the ice cover thins, ice may flow more easily into the channels, preventing the Northwest Passage from regularly opening in coming decades.”
So, if the Northwest Passage opens, it’s due to increased “melting” caused by global warming. If the Northwest Passage doesn’t open, it’s due to more easily flow of ice into the channels, caused by global warming.
Yep, that sounds like classic “Climate Science” alright.

“Vincent (09:45:02) :
On that Ian Pilmer link, I sometimes wonder if he knows what he’s talking about. In one paragraph he writes that in the past, carbon dioxide levels were 1,000 times higher than the present.
Utter nonsense!”
Assuming he means precambrian.
Careful. So far as I know that is a matter of great dispute, with 30% by no means the upper guess, some think CO2 was the principle gas. A lot papers mention this, mostly geological and that is Plimer’s disipline.
I’ll leave it for you to dig out any papers you wish.

Tenuc at 12:00:11 today.
-regarding photos from link you posted at- klimadebat.dk/forum/vedhaeftninger/seaice4years.gif
Great photos, could you please post the original source for these, it would be interesting for future comparisons.

Concerning the sea-ice-extent trend, have you considered plotting a 365-day moving average? That would remove the seasonal variation. Trends would be more apparent. Thanks.

The ice extent is about 245 000 more than last year and reducing the gap to 2008 currently using JAXA figures.
Bill Illis,
In fact the concentration of ice in the NW passage is now the lowest it’s been
http://ice-glaces.ec.gc.ca/prods/WIS138C/20090823234700_WIS138C_0004535902.gif
and the temps for the next few days are still good for it still to reduce further, so the best time to traverse it is still to come.
Regards
Andy

Ah, sorry Andy but from the JAXA data the difference is now only 170,000! 2009 had a series of large sea ice losses.

astonishing! on 1st of june at least 3 of the curves show a very dramtic daily peak that cannot be seen anywhere else in the diagram.
either someone is firing 100k rockets into sky making much dust (isnt the US celebrating on 4th of july?) or there is some really bad bug in the computation pipeline that produced those track.

Read it and weep:
According to a study done using NASA ICEsat satellite data, ice volume shrank dramatically 2004 to 2008:
http://www.nasa.gov/images/content/365869main_earth2-20090707-full.jpg

NASA Satellite Reveals Dramatic Arctic Ice Thinning
07.07.09
PASADENA, Calif. – Arctic sea ice thinned dramatically between the winters of 2004 and 2008, with thin seasonal ice replacing thick older ice as the dominant type for the first time on record. The new results, based on data from a NASA Earth-orbiting spacecraft, provide further evidence for the rapid, ongoing transformation of the Arctic’s ice cover.
Scientists from NASA and the University of Washington in Seattle conducted the most comprehensive survey to date using observations from NASA’s Ice, Cloud and land Elevation Satellite, known as ICESat, to make the first basin-wide estimate of the thickness and volume of the Arctic Ocean’s ice cover. Ron Kwok of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., led the research team, which published its findings July 7 in the Journal of Geophysical Research-Oceans.
The Arctic ice cap grows each winter as the sun sets for several months and intense cold ensues. In the summer, wind and ocean currents cause some of the ice naturally to flow out of the Arctic, while much of it melts in place. But not all of the Arctic ice melts each summer; the thicker, older ice is more likely to survive. Seasonal sea ice usually reaches about 2 meters (6 feet) in thickness, while multi-year ice averages 3 meters (9 feet).
Using ICESat measurements, scientists found that overall Arctic sea ice thinned about 0.17 meters (7 inches) a year, for a total of 0.68 meters (2.2 feet) over four winters. The total area covered by the thicker, older “multi-year” ice that has survived one or more summers shrank by 42 percent.
Previously, scientists relied only on measurements of area to determine how much of the Arctic Ocean is covered in ice, but ICESat makes it possible to monitor ice thickness and volume changes over the entire Arctic Ocean for the first time. The results give scientists a better understanding of the regional distribution of ice and provide better insight into what is happening in the Arctic.
“Ice volume allows us to calculate annual ice production and gives us an inventory of the freshwater and total ice mass stored in Arctic sea ice,” said Kwok. “Even in years when the overall extent of sea ice remains stable or grows slightly, the thickness and volume of the ice cover is continuing to decline, making the ice more vulnerable to continued shrinkage. Our data will help scientists better understand how fast the volume of Arctic ice is decreasing and how soon we might see a nearly ice-free Arctic in the summer.”
In recent years, the amount of ice replaced in the winter has not been sufficient to offset summer ice losses. The result is more open water in summer, which then absorbs more heat, warming the ocean and further melting the ice. Between 2004 and 2008, multi-year ice cover shrank 1.54 million square kilometers (595,000 square miles) — nearly the size of Alaska’s land area.
During the study period, the relative contributions of the two ice types to the total volume of the Arctic’s ice cover were reversed. In 2003, 62 percent of the Arctic’s total ice volume was stored in multi-year ice, with 38 percent stored in first-year seasonal ice. By 2008, 68 percent of the total ice volume was first-year ice, with 32 percent multi-year ice.
“One of the main things that has been missing from information about what is happening with sea ice is comprehensive data about ice thickness,” said Jay Zwally, study co-author and ICESat project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “U.S. Navy submarines provide a long-term, high-resolution record of ice thickness over only parts of the Arctic. The submarine data agree with the ICESat measurements, giving us great confidence in satellites as a way of monitoring thickness across the whole Arctic Basin.”
The research team attributes the changes in the overall thickness and volume of Arctic Ocean sea ice to the recent warming and anomalies in patterns of sea ice circulation.
“The near-zero replenishment of the multi-year ice cover, combined with unusual exports of ice out of the Arctic after the summers of 2005 and 2007, have both played significant roles in the loss of Arctic sea ice volume over the ICESat record,” said Kwok.

Hi Alexej-

What is more exact: Measuring per satellite from 1000 km up, or by plane from low down?
When Polar 5-data is finally published, this stuff will be obsolete.

http://www.nasa.gov/topics/earth/features/icesat-20090707r.html
Above is a link to the NASA ICESat website, which gives the text of the original news release.
The satellite measurements could very well be much more accurate than aircraft data. The satellite was designed to measure ice volume, using a laser altimeter, and has a unique vantage point, able to see the whole area. It was also subject to a whole program of validation before data from it was used. The orbit is 600 km above the surface of the earth. Laser altimeters are capable of extreme accuracy:
http://en.wikipedia.org/wiki/LIDAR
Here’s a link to the validation plan, from NASA, and here are the cryosphere (ice measurement) specs:
http://www.csr.utexas.edu/glas/pdf/plan/validation_plan_v1_oct2001.pdf

Cryosphere: the measurements should support determination of elevation change to an accuracy of 1.5 cm/yr in a 100 km x 100 km region where surface slopes are < 0.6° (1:100), which is typical for more than 80% of the polar ice-sheet surface; however, on the East Antarctic plains where surface slopes are < 0.2°, the accuracy requirement is 0.5 cm/yr in a 200,000 km2.

This is hard scientific data, showing a massive change in ice volume compared to any reasonable experimental error. It comes from a satellite in space, far from most reasonable sources of accidental human interference.
It’s apparently working the way it was designed to work, but is telling the readers of WUWT something they don’t want to hear.
Will they listen?

Re: Leland Palmer (07:10:32)
Listen to what? That we can sail around more up there now? That’s good! That some areas in Northern Canada may be able to support a settlement of people soon? That’s good! Just exactly what are people afraid of?
I’ll say it for the “umpteenth” time: warmth is good!!

“”” jorgekafkazar (16:25:33) :
John F. Hultquist (14:51:33) : “…I’m still not sure what the significance would be if this Ocean becomes ice-free, or nearly so, for a few weeks even as I doubt that will happen. Will not the energy of the water move to the atmosphere faster with no ice cover?”
Yes, given that (1) the emissivity of open water is about 0.993, much higher than ice, “””
jorje, I’m interested in your source for the emissivity of open water; also over what spectral range is that.
It’s not that I am doubting you; I would just like to know the reference source of that figure.
For solar spectrum wavelengths, I would expect a number more like 0.97, given that the normal incidence reflection coefficient is about 2%, and about 3% for diffuse reflectance. But I can appreciate that since water is almost totally absorbing in the 10-100 micron range, that the IR emissivity would be high.
Is that a measured or a calculated value ? By the way; what IS the corresponding figure for ice ?
George

How many of the attempts at the NW passage actually made it through?
DaveE.