A new article in Science Express, “High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years” (subs. req’d) examines “The last two abrupt warmings at the onset of our present warm interglacial period.” The article explores the underlying causes of
… abrupt shifts of northern hemisphere atmospheric circulation resulting in 2-4°K changes in Greenland moisture source temperature from one year to the next.
The article concludes that
… polar atmospheric circulation can shift in 1-3 years resulting in decadal to centennial scale changes from cold stadials to warm interstadials/interglacials associated with astounding Greenland temperature changes of 10°K. Neither the magnitude of such shifts nor their abruptnesses are currently captured by state of the art climate models.
The time to act is yesterday.
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This means Greenland’ ice will melt in big chunks … resulting in catastrophic flooding.
“The time to act was yesterday.”
This gets the award for being the most underestimated statement of all times.
The Greenland Ice Sheet will not melt in big chunks or cause catastrophic flooding suddenly. Ice sheets do not respond that fast and the Greenland Ice Sheet mass loss has and will be driven not mainly by surface melt but by faster flow driven by changes at the ice front, not by changes in meltwater delivery to the base. Thinner ice at the calving front like with ice shelves is more poorly buttressed by the fjord walls, which leads to calving, which leads to acceleration of ice behind the calving front. This is what happened at Jakobshavns where the acceleration began after ice shelf loss at the glacier front and the acceleration propogated from the ice front and worked its way upglacier. http://www.realclimate.org/index.php/archives/2008/04/moulins-calving-fronts-and-greenland-outlet-glacier-acceleration/langswitch_lang/in
That is not to say rapid climate changes are not an issue. One other point these rapid climate changes occurred at the end of an ice age which is not by any means an analog for the opposite, which is going into a exceptional warming
But the point is that there are a whole bunch of folk urging us to act the day after tomorrow who were doing that yesterday and the day before yesterday. Ooops sorry they simply said there was no problem the day before yesterday.
I’m assuming (my sub does not allow me past the abstract) that they speak to the medieval warm period? By any chance do they offer additional insights to the cause of the Greenland melt at that time? (The current melt is revealing vegetation from that time period.)
I’m also going to hazard a “guess” and say that the denier/delayer crowd will crow that this “demonstrates” that AGW is not responsible for the current melt — after all, “it has happened before.” (Nature of *THIS* logical fallacy is the “hasty generalization” http://www.fallacyfiles.org/hastygen.html )
Gary Herstein — The astounding sudden warming in Greeland happened at the end of Younger Dryas, often taken as the signal for the beginning of the Holocene (I use a bit later, 10,428 ybp). AFAIK, this is not be modeled satisfactorily.
However, the similar, but much smaller, 8.2 kya event has been modeled. There is a paper by Gavin Schmidt and many others — perhaps Hansen is the lead author.
In that event, temperatures in central Greenland plumeted 3 K and then rapidly recovered, in two bursts, so to speak. Both bursts took over a century, but each appears to be comperable in temperature increase to what the globe as a whole has experinced in the last 100–150 years.
To the extent I understand the climatology, both Younger Dryas and the 8.2 kya event involved the sudden introduction of large quantities of ice into the North Atlantic. Roughly speaking, it stayed cold until the ice melted. Unless a very large meteorite strikes Greenland, there are no longer means to produce a similar cooling followed by warming event.
In summary, these pre and early Holocene events offer little insight into our current predicament.
Joe, you seem to have left out the part were it says that these events happened 11-14000 years ago! So rapid “Global Climate Change” has happened before, in the absence of human actions. 60 years in the 1st case and 2-3 years in the other!
But of course that doesn’t fit your agenda does it.
beefeater….
Over your head and long gone.
You totally missed the point of Joe’s post.
Beefeater — I didn’t leave it out. Most readers understand that this occurred in a warming trend driven by changes in the earth orbit coupled with the amplifying feedbacks that accelerate most major warming trends.
Now humans have taken over the role of external forcing. The point is the more we poke the climate beast, the more likely it will react violently.
“Now humans have taken over the role of external forcing.”?
I would really like to see the peer reviewed, published research showing that in the absence of human beings “Global Climate Change” would not exist. No other “external forces” are impacting the globe! It’s “settled science” don’t you know.
That just might be the most arrogant and juvenile statement I’ve seen here.
i’d like to revisit this “gravity” idea. for instance, is there any cheap easy way to fly away to another, healthier planet?
beefeater — Of course slow changes, relatively speaking, occur all the time. It seems that only at the transition from galacial to interglacial there are some rapid changes.
Anyway, here is a peer reviewed, published paper, together with commentary which addresses your point:
Temperatures for the past 1200 years:
http://www.sciencemag.org/cgi/content/abstract/311/5762/841
http://www.realclimate.org/index.php/archives/2006/02/a-new-take-on-an-old-millennium/langswitch_lang/po
“I would really like to see the peer reviewed, published research showing that in the absence of human beings Global Climate Change would not exist.”
Of course climate change would still exist. The question is, what are the various factors and how important are they. If you really want to learn something, you can start by reading portions of the IPCC 4th report.
Main IPCC web site: http://ipcc.ch
Working Group Report on “The Physical Science Basis”:
http://www.ipcc.ch/ipccreports/ar4-wg1.htm
If you really want to dig in, there are about 1,000 references listed at the end of the Chapter 9 supplemental material.
For the less technically inclined (that would include me), the Summary for Policymakers at:
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
will answer your question about Joe’s statement that “Now humans have taken over the role of external forcing.”
Of course, if you don’t want to take the word of the IPCC and you have the required expertise, you can read the 1,000 articles and see if the synthesis of the experts from 130 countries is correct.
Note also the Lawrence et al paper on the impact of Arctic sea ice loss on Arctic and sub-Arctic temperatures. The beast’s tail is beginning to twitch…
Gareth — Could you kindly provide a better reference to that paper? I’d like to read it.
Sure David. I blogged about it here. Do follow the link to the Nature blog about the paper, as well. There’s also good post at Open Mind – The Big Thaw, currently at the top of the page…
Cheers
Gareth — I found it. According to that study, probably does not much accerlerate Greenland ice sheet melting, which is what I wanted to check.
To make electric-car electric-truck can walk around world with no stop
HELLO
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the invention consist of new electric – charger[my design ] and two groups of batteries.
batteries.group / A / batteries. group / B /
how it work ( general view ) ?
when / A /battery group supply the electric engine of car by the electric .
in the same time the / B / in charging . when / A / be empty , the / B / will be supplying the electric engine of car by the electric , and / A / in charging.
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approximately free may use it in the ship
designer
ENG.Amir kara fallah-syria
Email :karafallah1@hotmail.com