That’s not good news for lots of folks. A reliably open northwest passage would be a shippers dream.

IF… you seem to be stuck in a groove, caught in a closed loop of just one irrational thought. Please try and think beyond the square, or loop if you prefer.

Temperatures go up and temperatures go down. I told you that the Earth has been in warmer periods many times during our current Holocene interglacial, there is no reason to fear any catastrophe.

Did you have a look at the evidence of Medieval Warm Period? If you realise the above fact then all your subsequent arguments for a doomsday scenario become superfluous.

And if they do, fiddle while Rome burns, so to speak, should they?

Undoubtedly. Better than living in misery under the weight of carbon taxes to support the perpetrators of this scam in a life of luxury, which will accomplish nothing even according to the faulty science espoused by the doomsayers.

Now that I have brought you glad tidings of great joy, please treat yourself to a coffee. Relax and enjoy life.

Thanks, I think.

But, if runaway climate change accelerates, humanity won’t be doing much relaxing and enjoying of life, IMO. And if they do, fiddle while Rome burns, so to speak, should they?

Huge decreases in ice volume in only a few years are fully consistent with a runaway climate change scenario, unfortunately.

Thats where your trouble lies.
Please educate yourself on this. If your realise that the Earth has been in warmer periods during many periods during our current Holocene interglacial, including during the Medievalk Warm Period, then you will understand that whatever is happeneing now has happened before in our recent past and thus there is no reason to fear any catastrophe.

Here is a good place to start: http://www.co2science.org/data/mwp/mwpp.php

Now that I have brought you glad tidings of great joy, please treat yourself to a coffee. Relax and enjoy life.

We don’t know about Arctic ice extent in the Medieval warm period, or at least I don’t.

What I do know is that an extremely dramatic melting of the polar icecap has occurred in the last few years, at the same time as thousands of other well established scientific indicators of global warming are telling us that dramatic warming is occurring.

The data from the polar icecap melting (decrease in ice volume) is dramatic, and scientifically established to be far beyond any reasonable experimental error.

Ice volume decreased from 2003 to 2008, a fact that has been disputed on this blog.

Posters on this board who thought that the wind just happened to be piling the Arctic sea ice up were apparently wrong.

The original article, that says the the changes in ice extent in 2007 were due to the wind is wrong.

The changes in ice area that occurred in 2007 were correlated with measured changes in ice volume in 2007.

That ice area and volume are correlated is of course obvious, and should have been seen as the simplest assumption on this blog all along.

When taken in context with thousands of other indicators of global warming, including land and sea temperature records, this is another indicator of probable catastrophe. Certainly, such huge declines are totally unsustainable, if they continue. These changes in ice volume and extent are real, the ICESat data tells us, and appear to be orders of magnitude larger than in the reasonably undisturbed baseline period from the 1970′s through 2000.

If this is happening now then, probably more than this happened during the several centuries in human historical memory (the Medieval warm period) when it was warmer than now.

Do you have anything to say about that?

What the NASA satellite ICESat is telling us is that there was a massive change in ice volume, that coincided in time with the 2007 ice extent minimum.

So, apparently, ice volume does correlate with ice extent. The wind does not significantly decouple this correlation, apparently.

The bottom line from this NASA data is that the Arctic is melting. These are huge changes, occurring far ahead of schedule.

Some expect the effects of Arctic melting to be good, or at least economically good.

Others, expect the effects of polar icecap melting to be very bad, and expect that those effects will extend far beyond the narrowly defined limits of this thread.

The climate is indeed all connected, fortunately or unfortunately.

Since I’m not allowed to respond to questions about what the significance of a 2.2 ft decline in ice thickness in only four years is, beyond the narrowly defined limits of this thread, let’s talk about the ice/albedo feedback:

http://en.wikipedia.org/wiki/User:Atmoz/Climate_change_feedbacks

Sea ice feedbacks
Aerial photograph showing a section of sea ice. The lighter blue areas are melt ponds and the darkest areas are open water, both have a lower albedo than the white sea ice. The melting ice contributes to the ice-albedo feedback.

At high latitudes, temperatures get low enough that sea water freezes into ice. Sea ice strongly impacts the climate through two different positive feedbacks. First is the sea ice-albedo feedback (or ice-albedo feedback). As temperatures increase, the sea ice melts, resulting in a lower surface albedo, and increasing the amount of solar radiation absorbed, which reinforces the initial warming.[27] Reviews of various models show that the magnitude of this feedback is uncertain due to differences in ice dynamics, and in their treatment of clouds.[28] The albedo has been shown to change in two ways: changes in the areal extent of the ice, and changes in the multi-year ice such as ice thickness, and melt pond characteristics. Sea ice models that incorporate the multi-year ice feedback are more sensitive to initial changes in temperature.[27]

Sea ice also acts as an insulator between the ocean and the atmosphere. As the ice melts, it allows more liquid water to evaporate into the air. This latent heat flux from the ocean to the atmosphere results in additional warming of the boundary layer. Melting of sea ice also results in an increase in the poleward moisture flux from the tropical oceans.[29]

For readers who are interested, beyond the narrowly defined limits of this thread, in the significance of these findings from NASA, the Wikipedia article lists several other positive feedback effects that are very worrisome, IMO.

The ice thickness declined by 2.2 feet over only four years, according to NASA. This is good, hard scientific data, gathered from an extremely good, well calibrated source. The measured decline is far above any reasonable experimental error.

[snip - waaaayyyyy off topic. When we have a thread on methane you can post this. Right now the discussion is sea ice, and I won't have you hijack this thread to satisfy that whim. - Anthony]

Leland Palmer what is the gloom and doom all about? Why dont you go away and weep by yourself at your imaginary perils. Maybe they seem real to you, but you seem impervious to logic, so I really dont know how you can be helped.

Have a look at the temperature records of the GIPS2 ice core data. During much of the Medieval warm period the temperature in Green land was 1 to 1.5 C warmer than today. There was nothing catastrophic about this period, quite the contrary. The catastrophe happened when the world cooled after this period into the little ice age and didnt recover till we warmed up again.

During the last century and a half when we have warmed slightly we have addded billions to our population and yet managed to feed ourselves.

Just think about all this and then come back and tell me if this makes any sense to you.

So George was right. I still believe it is møch måre æccurate if you are møch nearer. But we have to wait whåt the Eisdeckendickemessinstrument said.

Apparently not. sad to say.

Hi George E. Smith-

Here’s their methodology:

http://www.nasa.gov/topics/earth/features/icesat-20090707.html

Figure 1: ICESat measures the distances to the top of the snow cover and to the sea surface. The difference between the two quantities gives the total “freeboard” measurement; that is, the amount of ice above the water line relative to the local sea level. Credit: Courtesy of Norbert Untersteiner, University of Washington
> Larger image
This schematic shows the geometric relationship between the amount of ice above the water line, snow depth, and ice thickness. Figure 2: This schematic shows the geometric relationship between freeboard (the amount of ice above the water line), snow depth, and ice thickness. Buoyancy causes a fraction (about 10 percent) of sea ice to stick out above the sea surface. By knowing the density of the ice and applying “Archimedes’ Principle” — an object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object — the total thickness of the ice can be calculated. Credit: Ron Kwok, NASA/JPL
> Larger image
ICESat measurements of the distribution of winter sea ice thickness over the Arctic Ocean between 2004 and 2008 Figure 3: ICESat measurements of the distribution of winter sea ice thickness over the Arctic Ocean between 2004 and 2008, along with the corresponding trends in overall, multi-year and first-year winter ice thickness. Credit: Ron Kwok, NASA/JPL

Nice video, showing delcine in ice volume, year by year.

http://www.nasa.gov/mov/326195main_winter_seaicethickness30fps.mov

DaveE.

And let me guess, they read the altitude of the ice surface (above sea level), and use the differential to infer an ice thickness, then allowing for the underwater volume they compute the total ice volume, or something like that.

So what is the resolution of their camera in terms of how small a piece of ice can it see, and is their spatial sampling sufficient to correctly determine the ice area; or is it like most sampling studies, severely compromised by aliassing noise, of even the average.

Based on the inputs from that silly stuck in the ice yacht, the spatial frequency of the ice areas is quite high; so I would have to be convinced there isn’t a Nyquist violation in the data; but then nobody else worries about that so why should I.

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