A survey of climate scientists reveals uncertainty in their predictions of changes to the global climate, yet finds that they believe there is a real chance of passing a “tipping point” that could result in large socio-economic impacts in the next two centuries. The expert elicitation was conducted between October 2005 and April 2006 with a computer-based interactive questionnaire completed individually by participants. A total of 52 experts participated in the elicitation (see Table S2 in the PDF below for names and affiliations). The questionnaire included 7 events of crossing a tipping point. Elmar Kriegler and colleagues asked the climate experts to estimate the likelihood of impacts to components of the climate system under different warming scenarios.
The five systems discussed in the paper concerned major changes in the North Atlantic Ocean circulation, the Greenland and Western Antarctic ice sheets, the Amazon rainforest, and El Niño. The probabilities given by the experts varied widely, but on average, they assigned significant chances to a tipping point in this or the next century for at least the medium to high warming scenarios.
Using the experts’ more conservative estimates, the authors calculate a 1 in 6 chance that a tipping event will occur if the temperature increase in the next 200 years is between 2 and 4 degrees Celsius. For a higher temperature increase, the probability was just over 1 in 2. According to the authors, the results suggest that the large uncertainties that come with climate predictions do not imply low probability that catastrophic events will occur.
Since the survey was conducted in 2005 and 2006, I wonder if the opinions are equivalent today. They might have gotten more bang for their buck if they’d used a survey company like Gallup. I’m sure the results would be faster.
The paper is titled: Imprecise probability assessment of tipping points in the climate system
Elmar Kriegler, Jim W. Hall, Hermann Held, Richard Dawson, and Hans Joachim Schellnhuber,
Potsdam Institute for Climate Impact Research, PO Box 60 12 03, 14412 Potsdam, Germany; Department of Engineering and Public Policy, Carnegie Mellon
University, Pittsburgh, PA 15213-3890; School of Civil Engineering and Geosciences, Newcastle University, Newcastle-upon-Tyne NE1 7RU, United Kingdom;
Tyndall Centre for Climate Change Research, United Kingdom; and eEnvironmental Change Institute, Oxford University, Oxford OX1 3QY, United Kingdom
Edited by William C. Clark, Harvard University, Cambridge, MA, and approved February 2, 2009 (received for review September 16, 2008)
Here is their diagram of the tipping possibilities in the global climate system:
Here is the PNAS abstract
George E. Smith (16:07:22) :
But it is known from mining operations that the temperature increases by so much for every so many meters underground depth; presumably after some surface skin which is warmest on the outside.
I’ve read similar statements. I understood that air pressure was partly involved in the warming. The deeper you go, the greater pressure there is. Of course, the pressure hypothesis is also reasonable to keep core temps up.
Solar energy has (based on its time domain) no more than a few feet of influence on soil temps (its a common first year heat transfer problem of an infinite medium and mixed radiation convection boundary condition).
As for the calcs of flux, Lord Kelvin was the first to use the measured heat flux from the earth to calculate its age – and in doing so screwed up geological sciences for almost 50 years. He did conclusively prove the earth was much older than 6000 years – more in the 20 to 100 million year range – but this didn’t correlate with fossil records, which indicated a much longer time frame. It took the discovery of nuclear fusion to bring the two time calcs into sync….
In answer to your question, heat flux is a “constant”, and for purposes of global warming is considered such (if they consider it at all). Since most of the models deal with dT based on stored heat capacity and reradiation, I would think it could be dealt with as an offset in models, and wouldn’t require any real physics to be input (much like their models, in many respects!!!)
I read a book some time ago (and I apologize for not remembering the title … I read a lot of books) that basically reviewed studies that showed that expert opinion was no better than non-expert opinion (had no better prediction skill) when it came to complex areas with high degrees of uncertainties. I think this jives strong what most of us have probably experienced at some time or another. The media is full of ‘experts’ who may be very good at prediction of small perturbations from everyday events within their field (linear causality basically), but whose prediction is no better than non-experts once choas/complexity enters the picture (i.e. think of the current financial crisis and all those ‘experts’ with egg on their face).
I should mention that Kelvin was an old sob – who confidently predicted that heavier than air flying machines would never work…
George E. Smith (15:49:40) : I still hate tipping people; it’s a scam.
Great story! Yeah, that’s the east coast…
Reminded me:
Ah, the joy of tip-free New Zealand comes to mind! Loved the place. Wish I could live there. Like Oregon, but the size of California, with wonderful people. Though when I checked into the hotel and was handed my key with a single word question: “Milk?” I was just a little unsure… Seems I was being asked if I wanted a cup sized milk carton to make my tea civilized… Once I figured out what was meant, I took the milk… Then I was asked if I wanted to be :”knocked up in the morning?”… another long pause as we sorted out that that meant a ‘wake up call’ and had nothing to do with, er, reproduction. First night asked a waiter about the tipping thing and was it real, he assured me with great pleasure that Kiwi’s Did Not Need Bribes to do a good job.
But as to the earth’s climate having tipping points; given that the orbital parameters stay pretty much what they now are. No system that is as stable as the earth’s climate is, could possibly have tipping points, or it would have tipped a long time ago.
So forget climate tipping points; that’s also a scam; just like tipping is.
George, I’m not so sure. I think we DO have tipping points, in a nice Hysteresis system of ice ages. Unfortunately for the AGW herd, we have a hard limiting factor of some kind at each end, and we’re at the limit for the warming end. The only “tip” we can have is into an ice age sometime in the next hundred to few thousands of years. With any luck, we can figure out how to increase the natural temperature of the planet enough to prevent “tipping” back into an ice age (a fate that is inevitable if we don’t get some significant warming mechanism put together…)
I don’t know what drives the limit cases, but a brief inspection of the temperature and ice levels of the ice age cycles sure looks like a hysteresis system with limited oscillation ranges. see:
http://upload.wikimedia.org/wikipedia/commons/c/c2/Vostok-ice-core-petit.png
I’m not particularly worried. Look at the ice advance rate during a glacial and it works out to about 800 feet average laterally per year. You could out walk a year’s advance in one tea break… but the idea that we might push through what is repeatedly shown to be a hard ceiling to the warm side is, er, “odd thinking” IMHO… Once the light switch is clicked up, it can only click down, though it may take a while and an outside force to do it.
Is there any other term for ‘feedback loop leading to limit cases at each end with both ends stable” other than hysteresis? I find explaining it to non-tech folks tiring. (Though the light switch example usually works). Somehow we need to teach the AGWers that “feedback” has many flavors and only a few lead to runaway processes. I.e. growth is “S” shaped not exponential.
I think the most obvious objection (blatantly obvious) to this idea of ‘tipping’ point is that if there is a tipping point it MUST have occurred in the past. There is nothing unique about our current situation compared to the entire history of the planet. So where is this tipping point in the data? I see several tipping points, but they are all into and out of ice-ages!! No where in the data has there been 3-levels i.e. ice age to interglacial to runaway global warming desert earth. If this climate state didn’t exist in the past, it doesn’t exist as a viable state. There is a tipping point alright, but not in the direction AGW believers think it is.
Okay this is my first comment, but I’ve been watching this blog for about a year now, I like the articles and I like how Anthony surveys the weather stations and gives us good science about climate
I noticed recently that the UAH temperature went up for Febuary and it was no surprise considering Wichita has a warm Febuary, I was wanting to see if there was a non-AGW explanation for it, but in this link its pretty much explained
http://www.woodfortrees.org/plot/uah/from:1996/plot/hadsst2gl/from:1996
I noticed how all the previous temp spikes happened shortly after a spike in the SST data, there was such a spike less than a few months ago and global temps. may have responded to that, it’s going down again so it should drag temps. down with it. I selected a year or two before 1998 to see how SST’s helped make that year so hot, you could say SST data is like a window into the near future for temps, and has much more effect than the sun at the moment.
Well, should submit this, here goes nothing.
While the chart in my last comment works, this one is what I intended and works ‘better’:
http://upload.wikimedia.org/wikipedia/commons/f/f8/Ice_Age_Temperature.png
In it you can see the ice advance….
The fabulous tipping point, Hansen’s deus ex machina that will rescue his climate apocalypse theory just when it seems that nature does not want to cooperate. Do any of these so called experts have the wisdom and humility to admit that they just do not know the answer?
Regarding heat within the Earth and how it varies with depth and what it means at the surface:
http://www.absoluteastronomy.com/topics/Geothermal_gradient
Here is one quote:
“This estimate, corroborated by thousands of observations of heat flow in boreholes all over the world, gives a global average of 3×10−2 W/m². Thus, if the geothermal heat flow rising through an acre of granite
terrain could be efficiently captured, it would light two 60 watt
light bulbs.”
Bottom line: this source of heat is miniscule and can be disregarded as far as Earth’s temperature is concerned. On the other hand, the Sun . . .
Another graphic of natural climate change: click
Adam from Kansas,
That’s really interesting. I wonder if the satellite data can be broken out between land and sea temps.
And another interesting chart: click
Ice core data showing that CO2 has no discernable effect on temps: click.
The rise in CO2 is the effect of global warming, not the cause.
This is a cool way of doing science!
Soon, Gallup will be determining ALL the important science questions! Hey, we might finally get a grand unified theory! A T.O.E !!!! By polling consensus! I’m so excited about the future of science!
John F. Hultquist,
One acre is just over 4,000 square meters. That means geothermal heat is about .03 watts/meter.
Not a lot. But it heats at a constant pace, 24 hours a day, more than doubling its apparent effect when compared with solar insolence. And unlike sunlight, it heats equally at the equator and at the poles.
[This was just off the top of my head. I hope Leif doesn’t read this post!]
The only tipping point I care about is the one that delivers the fine wine from my glass to my taste buds.
Robert Austin (17:46:36) :
The fabulous tipping point, Hansen’s deus ex machina that will rescue his climate apocalypse theory just when it seems that nature does not want to cooperate. Do any of these so called experts have the wisdom and humility to admit that they just do not know the answer?
They appear to have neither the wisdom nor the humility. However, there is still time left for them to redeem themselves.
On a related point, increasing numbers of scientists are holding a open sceptical position. http://www.epw.senate.gov/public/index.cfm?FuseAction=Minority.Blogs&ContentRecord_id=10fe77b0-802a-23ad-4df1-fc38ed4f85e3
(at the risk of claiming a consensus…)
Also from the above epw link I particulary like the following.
UN IPCC Scientist Dr. Steven M. Japar, a PhD atmospheric chemist who was part of Intergovernmental Panel on Climate Change’s (IPCC) Second (1995) and Third (2001) Assessment Reports, and has authored 83 peer-reviewed publications and in the areas of climate change, atmospheric chemistry, air pollutions and vehicle emissions, challenged the IPCC’s climate claims.
“Temperature measurements show that the [climate model-predicted mid-troposphere] hot zone is non-existent. This is more than sufficient to invalidate global climate models and projections made with them!” Japar told the minority staff on the Environment and Public Works Committee on January 7, 2009.
An IPCC Apostate.
E.M Smith — I agree with you completely. There is an obvious limit. Rather than hysteresis (which seems a good enough word also) I think of it as ‘clipping’. At the top end we are reaching saturation. The first time I saw a graph of the temperature going into and out of ice ages that is what immediately struck me — it ends at approximately the same level every time — that can’t be just a coincidence. What would explain this? Saturation. (see http://www.ianschumacher.com/maximum_temperature.html for an incomplete explanation).
I think I read that someone at the ICCC had a similar explanation (but probably more accurate and scientific) based on conservation of energy.
It also seems fairly obvious to me that the current thinking on runaway greenhouse effect on Venus must be wrong. As is mentioned in another topic on this thread, what about latent heat, what about internally generated heat? That has to be the explanation for the high temperature on Venus … there is no way that the greenhouse effect could create temperatures higher than that of a blackbody … it is not possible.
Robert Austin “The fabulous tipping point, Hansen’s deus ex machina”.
What a fabulously clever statement! Mind if I borrow it sometime? 🙂 Yes it totally is his deus ex machina, LOL … totally.
These guys are stupid, all they had to do was consult the
Goracle! Or run the Mr. Peabody climate model…Sherman!
…… set the way-back-machine to the future!
Me, I’m sticking with my calibrated Ouija board!
steelbound (14:14:04) :
Linked to: http://xkcd.com/556/
I LOVE IT! thanks for posting that.
I did a render a couple of weeks ago with obama as don quixote..if interested:
http://www.cricket-studio.com/Renders/TiltingAtTurbines
“science by polls” courtesy of PNAS: – How many in favor? – How many against? Carried! Next issue? Since already the democratic process is highly perverted and as a result the level of political discourse tends asymptotically toward zero, we can expect the same with science: after all why should the garbage cleaner’s opinion be good enough for electing the leader of the free world and not be taken in account when reviewing science. It is the logical stage.
Smokey (18:15:16) :
If Leif sees you are referring to the sun’s insolence he’ll probably bust a gut laughing.
John H.
You’re right, it’s insolation. There was a disconnect between the keyboard and the screen pixels. I blame global warming.