We covered this earlier, but this is a new press release on the subject today.
From the University of Washington via Eurekalert
Model shows polar ice caps can recover from warmer climate-induced melting
A growing body of recent research indicates that, in Earth’s warming climate, there is no “tipping point,” or threshold warm temperature, beyond which polar sea ice cannot recover if temperatures come back down. New University of Washington research indicates that even if Earth warmed enough to melt all polar sea ice, the ice could recover if the planet cooled again.
In recent years scientists have closely monitored the shrinking area of the Arctic covered by sea ice in warmer summer months, a development that has created new shipping lanes but also raised concerns about humans living in the region and the survival of species such as polar bears.
In the new research, scientists used one of two computer-generated global climate models that accurately reflect the rate of sea-ice loss under current climate conditions, a model so sensitive to warming that it projects the complete loss of September Arctic sea ice by the middle of this century.
However, the model takes several more centuries of warming to completely lose winter sea ice, and doing so required carbon dioxide levels to be gradually raised to a level nearly nine times greater than today. When the model’s carbon dioxide levels then were gradually reduced, temperatures slowly came down and the sea ice eventually returned.
“We expected the sea ice to be completely gone in winter at four times the current level of carbon dioxide but we had to raise it by more than eight times,” said Cecilia Bitz, a UW associate professor of atmospheric sciences.
“All that carbon dioxide made a very, very warm planet. It was about 6 degrees Celsius (11 degrees Fahrenheit) warmer than it is now, which caused the Arctic to be completely free of sea ice in winter.”
Bitz and members of her research group are co-authors of a paper about the research that is to be published in Geophysical Research Letters. The lead author is Kyle Armour, a UW graduate student in physics, and other co-authors are Edward Blanchard-Wrigglesworth and Kelly McCusker, UW graduate students in atmospheric sciences, and Ian Eisenman, a postdoctoral researcher from the California Institute of Technology and UW.
In the model, the scientists raised atmospheric carbon dioxide 1 percent each year, which resulted in doubling the levels of the greenhouse gas about every 70 years. The model began with an atmospheric carbon dioxide level of 355 parts per million (in July the actual figure stood at 392 ppm).
In that scenario, it took about 230 years to reach temperatures at which the Earth was free of sea ice during winter. At that point, atmospheric carbon dioxide was greater than 3,100 parts per million.
Then the model’s carbon dioxide level was reduced at a rate of 1 percent a year until, eventually, temperatures retreated to closer to today’s levels. Bitz noted that the team’s carbon dioxide-reduction scenario would require more than just a reduction in emissions that could be achieved by placing limits on the burning of fossil fuels. The carbon dioxide would have to be drawn out of the atmosphere, either naturally or mechanically.
“It is really hard to turn carbon dioxide down in reality like we did in the model. It’s just an exercise, but it’s a useful one to explore the physics of the system.”
While the lack of a “tipping point” could be considered good news, she said, the increasing greenhouse gases leave plenty of room for concern.
“Climate change doesn’t have to exhibit exotic phenomena to be dangerous,” Bitz said, adding that while sea ice loss can have some positive effects, it is proving harmful to species such as polar bears that live on the ice and to some people who have been forced to relocate entire villages.
“The sea ice cover will continue to shrink so long as the Earth continues to warm,” she said. “We don’t have to hypothesize dramatic phenomena such as tipping points for this situation to become challenging.”
The research was funded by the National Science Foundation, the Davidow Discovery Fund and the National Oceanic and Atmospheric Administration.
For more information, contact Bitz at 206-543-1339 or bitz@atmos.washington.edu, or Armour at 858-610-3812 or karmour@uw.edu.
The paper is available at http://www.agu.org/journals/pip/gl/2011GL048739-pip.pdf.
Bottom line :
Heat ice above zero degrees and it melts. Cool the water below zero degrees and it re-freezes.
Anyone need a multi-million pound computer model to tell them that?
AH yes, computer models tell us; that super models cannot compute…and super models tell us that computer models cannot model…ssoooo who do we believe… personally i’m all about the super model, but then again thats just me
Anything is possible says: August 17, 2011 at 5:54 pm
“Anyone need a multi-million pound computer model to tell them that?”
I know of a similar folly. A researcher here, an IPCC author, used his supercomputer to draw a colorful map showing the coastal areaa that are domed to be inundated if the sea level is to rise by 1 m or so. His “remarkable result” made a story on TV! I guess an elementary school boy/girl could do the same once he/she is given a cheap color pencil and a white contour map.
“In the new research, scientists used one of two computer-generated global climate models that accurately reflect the rate of sea-ice loss under current climate conditions, a model so sensitive to warming that it projects the complete loss of September Arctic sea ice by the middle of this century.”
So why are we all trying to predict this year’s minimum? Can’t these models just tell us what it will be? ;o)
… and I won’t even touch the “model so sensitive to warming” bit.
30 year averaged, measured solar irradiance (NREL redbook) in Nome, Alaska (64.5 N latitude) in kWhr/m^2/day-
Oct (1.0), Nov (0.3), Dec (0.1), Jan(0.2), Feb(0.8).
1 kWhr/m^2/day = 41.7 W/m^2 on average.
Thus, average solar insolation is-
Oct (41.7 W/m^2), Nov (12.5 W/m^2), Dec (4.2 W/m^2), Jan (8.3 W/m^2), Feb (33.4 W/m^2).
Open ocean at 273 K emits 315 W/m^2.
Any open water at this latitude or higher will re-freeze in winter.
All you need do is tune the model to CO2.
Not sure of the exercise.
If they want it quicker just raise the positive feedback.
If you’re going to lie might just as well reach Gore’s level.
(sigh)
It never ends.
So then, it isn’t worse than they thought? We aren’t doomed? Hallelujah! sarc/off
No tipping point, huh. Well I guess that’s something. Put that in your pipe and smoke it, Serreze.
Wait – so now models are OK to use for forecasting?
I thought models were bad evil things thaty cannot be trusted?
“A growing body of recent research indicates that, in Earth’s warming climate, there is no “tipping point,” or threshold warm temperature, beyond which polar sea ice cannot recover if temperatures come back down.”
—————-
1st. What warming climate?
2nd. Why on earth would a scientist with god knows how much knowledge and experience ever in this context use the word “IF”?
Could it be this “growing body” doesn’t believe in re-occurring Ice Ages?
Talk about denial!
Well Bystander, for once, you seem to agree with the rest of the commenters, whom even you may have noticed, are pretty dismissive of “models”.
Am I missing something here, they say ice free winter that means above freezing right. Sooo the winter tempeature must have increased from 30 to 50 below freezing to above freezing to melt, right. I would then say we will have just a few more issues besides melting ice.
Did they also leave out the logarithmic characteristic of increasing CO2. I did not read the paper.
You really are a bystander. Here’s a hint, we’re making fun of these people and their goofy model.
If you want to play, you should suit up.
Doesn’t matter.
At the actual latitudes of actual sea ice minimums (80 north latitude at minimum to the pole), there is no difference between the amount of energy absorbed by the so-called “black” low-albedo open oceans and “white” (high reflectivity) sea ice.
Both reflect within 1 percent of the same amount of energy, or, to phrase it differently, both absorb within 1% of the same amount of energy.
And, making things worse – as usual – the open oceans contribute MORE towards cooling the world than ice-covered waters. So …. open water in the Arctic (regardless of reason) cool the planet.
As we have recently seen, since the DMI measurements of summertime Arctic temperatures at 80 north (the southern boundary of the minimum sea ice extent) have been steadily decreasing since 1958.
If. If you take a climate model with very high climate sensivity then the ice melts. If…
You are missing the point – the point is that models that show warming are dismissed but along comes a study that is appears useful in spreading skepticism and all of a sudden models are useful.
That sure looks like whole lot of pre-decided belief selectively embracing “evidence’.
And that ain’t science folks..that is a belief system.
.
As a retired geology professor, whenever I see an article like this I want to shout (and do so to the point of annoying my wife), “For Christ’s sake, hasn’t anyone ever taken basic physical and historical geology courses?” It seems to me that a great majority of the nonsense that constitutes the panic over “climate change” or whatever it’s being called these days would be no surprise at all to anyone who took (and passed) intro geology courses. This amazement that ice melts when it gets warm or freezes when cold is almost a simple definition of the Pleistocene with its periods of ice sheet advance and interglacial ice melt. For gripes sakes, quit dorking around with worthless “environmental studies” in college and take some real science courses.
Bystander,
Incorrect, as usual. GCM models confidently predicted a “tropospheric hot spot,” which was said to be “the fingerprint of global warming.”
But the models were wrong.
“Climate change doesn’t have to exhibit exotic phenomena to be dangerous,” Bitz said, adding that while sea ice loss can have some positive effects, it is proving harmful to species such as polar bears that live on the ice and to some people who have been forced to relocate entire villages.”
===========
And this would be different, how, of any species on Earth.
Get used to it, the barbarians are always crashing the gate.
Wow they need a model to understand that melted water can refreeze? Amazing.
So a complete absence of sea ice in summer within 40-50 years. Hmmm.
As for the other scenario, they are talking about no sea ice in *winter.” All resulting from an average 6C increase in temperature. I’ve personally witnessed sea ice forming and it doesn’t have to be very far below freezing for that to happen. Color me skeptical, but how does a 6C warming eliminate winter sea ice? That is a pretty amazing claim.
Byastander, go back and read the comments more carefully from the top. No-one is putting much stock in these model scenarios. You make a valid point that one should not knee-jerk embrace models just because they fit one’s viewpoint. Well stated. However, I don’t see that happening on this thread.
Speaking of belief and ignoring the evidence, Bystander can you point me to one of the comments here that suggests these models are useful?
Everyone misses the point: They’ve used up all the scremongering they can get out of “ice-free arctic”. The persistence of ice in the arctic is starting to make their model predictions look bad.
So, voila, the models now predict persistent ice in a warming world.
“All that carbon dioxide made a very, very warm planet. It was about 6 degrees Celsius (11 degrees Fahrenheit) warmer than it is now, which caused the Arctic to be completely free of sea ice in winter.”
Back to the drawing boards! According to http://ocean.dmi.dk/arctic/meant80n.uk.php, it would take a 30 C increase at the north pole to make it ice free in winter.
This article was obviously not reviewed by WUWT readers.
Wow – you guys are still missing the point. Why select this model driven study to report here given all the other model driven activity?
That ain’t science folks..that is a belief system.
REPLY: Looks like a case of too many drinks at the Boca.
Update: Upon further inspection, I note that this “bystander” is none other than the troll known previously as “moderate republican” who has been banned. Sir, you’ve violated policy (twice now) and have been banned, so off my blog. Next time you pull tricks to get around that, I fully out you. Be upset if you wish, but that’s the deal. – Anthony