It seems depending on who you talk to, climate sensitivity is either underestimated or overestimated. In this case, a model suggests forcing is underestimated. One thing is clear, science does not yet know for certain what the true climate sensitivity to CO2 forcings is.
There is a new Paper from Tanaka et al (download here PDF) that describes how forcing uncertainty may be underestimated. Like the story of Sisyphus, an atmospheric system with negative feedbacks will roll heat back down the hill. With positive feedbacks, it gets easier to heatup the further uphill you go. The question is, which is it?
Insufficient Forcing Uncertainty Underestimates the Risk of High Climate Sensitivity
ABSTRACT
Uncertainty in climate sensitivity is a fundamental problem for projections of the future climate. Equilibrium climate sensitivity is defined as the asymptotic response of global-mean surface air temperature to a doubling of the atmospheric CO2 concentration from the preindustrial level (≈ 280 ppm). In spite of various efforts to estimate its value, climate sensitivity is still not well constrained. Here we show that the probability of high climate sensitivity is higher than previously thought because uncertainty in historical radiative forcing has not been sufficiently considered. The greater the uncertainty that is considered for radiative forcing, the more difficult it is to rule out high climate sensitivity, although low climate sensitivity (< 2°C) remains unlikely. We call for further research on how best to represent forcing uncertainty.
CONCLUDING REMARKS
Our ACC2 inversion approach has indicated that by including more uncertainty in
radiative forcing, the probability of high climate sensitivity becomes higher, although low climate sensitivity (< 2°C) remains very unlikely. Thus in order to quantify the uncertainty in high climate sensitivity, it is of paramount importance to represent forcing uncertainty correctly, neither as restrictive as in the forcing scaling approach (as in previous studies) nor as free as in the missing forcing approach. Estimating the autocorrelation structure of missing forcing is still an issue in the missing forcing approach. We qualitatively demonstrate the importance of forcing uncertainty in estimating climate sensitivity – however, the question is still open as to how to appropriately represent the forcing uncertainty.
h/t and thanks to Leif Svalgaard
And I’d add,
The irony here is that if they admitted that a large part of the 20th century warming wasn’t real and plugged in a much lower CO2 sensitivity, the models would work a lot better.
But then 90% of climate scientists could look forward to a career of driving taxis.
“The greater the uncertainty that is considered for radiative forcing, the more difficult it is to rule out high climate sensitivity, although low climate sensitivity (< 2°C) remains unlikely."
That is the flaw in this arguement. Uncertainty increases ALL possibilities, NOT skew certainty towards the few.
To date all empirical studies show that low climate sensitivity is more likely than high climate sensitivity.
Back to the drawingboard for the authors of this report.
Its worse than that he’s dead Jim! I feel the life force is draining away, I just wish someone would pay me shed loads of cash to write incoherent gobbledegook all day long and into infinity. How did we survive before we became deluded enough to believe we could ever really understand what is not meant to be understood because there really is no ryme or reason why our climate behaves as it does, it just does and as long as it does we might survive a little bit longer. I thought King Canute served as an object lesson to disuade deluded psychotic muppets from looking into dark corners where no sense exists and do something positive that might bear fruit, obviously not!
Tanaka et al refer to various papers by Mann and Jones to obtain air temperatures for their forcing, especially Mann and Jones (2003); i.e. ‘The Hockey Stick’ temperature record. They include a temperature ‘trace’ back to 1750, below the figure cited here, which includes a large dip around the Dalton Minimum, but they ascribe this to volcanic activity. Given that the Hockey Stick curve has to be one of the most discredited analyses ever published, why didn’t they use a non-tree-ring analysis such as Loehle (2007), shown in a recent blog by Roy Spencer.
http://www.drroyspencer.com/2009/07/how-do-climate-models-work/
Interesting that they cut the date-line off at 1750, just after an apparent huge rise in temperatures following the Maunder Minimum, as shown by proxies in Loehle’s analysis.
It could be much worse than previously thought. How can these people consider running a computer model an “experiment”?.
I’m glad to see they account for Missing forcing which is is treated as an independent parameter in each year.
It could be much worse than previously thought. How can these people consider running a computer model an “experiment”?.
I’m glad to see they account for Missing forcing which is treated as an independent parameter in each year.
The less we know, the higher chance things are “MUCH worse than we thought”.
I thought strong positive feed backs can be ruled out empirically, based on observations of real world.
This is rather a quaint conclusion that ECS is more likely to be greater than less. Over the 20thC and up to 2009 CO2 has increased ~ 38%; depending on what metric you choose temperature has increased 0.4C -0.7C; let’s say 0.5C. ECS from IPCC is reckoned to be ~3C for 2CO2; if a 38% increase has caused a 0.5C increase [excluding all other possible causes] than the remaining 62% increase in CO2 will have to cause a 2.5C increase which effectively increases the ECS to just over 4C; still just within the official IPCC range of 2-4.5C.
There is a certain irony here. In Australia coinciding with Gore’s platitudinous visit government pronouncements were 2-fold; firstly, atmospheric temperature was no longer important, the real indicators of AGW were OHC and sea levels; secondly, in respect of OHC and sea level, the rate of increase was accelerating. Of course OHC is declining as shown by NOAA and the gold-star, pro-AGW Levitus paper, let alone looking at Loehle’ s or Di Puccio’s calculations. And the sea levels are also flat to declining as shown by Jason-1. The irony is that while the pro-AGW announcements are all ratcheting up the doom and gloom trends the only thing that is increasing is the catch up in ECS which AGW has to achieve to reach its target of ~3C.
Just a quick glance at the paper, but their “Experimental” work involves running the same computer model with inputs tweaked. From this they obtain “Experimental” data.
The results are “Worse than we thought”.
LOL… I gather that th’ kitty is Sisyphus. Or maybe rising sea levels and a Puss with no boots, p’haps? 😉
This seems like a clever ploy by the alarmists to exaggerate the potential risk. To my simple mind it seems like if it was originally stated that temp rise by 2100 was to be between say 0 deg C and 2 deg C. By now implying that their forcings are underestimated and therefore the temp rise may be a greater range, the alarmists will say the possible temp rise might now range from 0 deg C to 4 deg C.
Hey presto, minimum potential temperature increase is unchanged but maximum temp has had a boost. It’s all sleight of hand, no empirical evidence, exaggerate the uncertainty. Greater the uncertainty, greater the potential max, greater the fear.
As Scotty would say “It’s worse than that, he’s dead Jim”.
By the way, I have a new theory of climate change.
After about 1650, when the last of the major Sun worshipping cults was biting the dust, Helios became displeased with the lack of respect and devotion. He decided to turn up the heat to let us know he wasn’t to be ignored, and to put a sweat on our brow.
But this resulted in influential humans blaming the increasing heat on the thinly veiled and deceitful nymph Carbonara, in order to place a tax on the laity for their role in making her get fatter by ordering too many takeaways from Italian charcoal pizza ovens.
Helios has decided to play these false prophets at their own game, and has ordered his Sunlings to stop shoveling the coal into the furnace of Phaeton.
Prove me wrong.
But, but… I thought natural variation is overwhelming the CO2 warming signal right now, according to AGW apologists. So how can the climate be all that sensitive to CO2?
Anyhow, I’m 100% certain that once the big meteor hits, it won’t matter how sensitive the climate is to CO2.
tallbloke (23:34:55) :
Does Leif Svalgaard agree with the characterisation of solar forcing displayed in the graph shown, and please would he explain what the red solar curve is representing in case I misunderstand it.
The red curve shows some representation of the solar cycle and does not seem too much out of whack. It has the smallest amplitudes of all the forcings, so is in line with what I would expect.
The simple answer is that CO2 has nothing to do with temperature.
David Wells (01:29:44) :
Live long and prosper.
This topic is way beyond my (non)ability. I hope someone can explain “inverse calculations” creating a more usable model. There seems to be quite an assumption in the abstract statement: “Equilibrium climate sensitivity is defined as the asymptotic response of global-mean surface air temperature to a doubling of the atmospheric CO2 concentration from the preindustrial level (~280ppm).
At the International Institute for Applied Systems Analysis (IIASA), Katsumasa Tanaka is the scientific coordinator of “Geoengineering to Avoid Overshoot: An Uncertainty Analysis”. “This project is motivated by the question as to how much geoengineering intervention would be required if it were to be used to avoid large global warming? How serious would be the environmental side effects caused by such an intervention?” This paper must be some of the intellectual/scientific foundations for this project.
I found something from 2008, I think, that might have more details.
http://www.uni-leipzig.de/energiemanagement/wien06_poster.pdf
In this piece Tanaka ea ask: “How can global-mean information on the carbon cycle, atmospheric chemistry, and climate system by systhesized to produce the post-industrial evolution of the Earth system?” Seems rather god-like.
A few interesting items from the IIASA homepage. It has as one of its projects a “Greenhouse Gas Initiative” which in 2008 opened towards “climate mitigation/adaptation and human development related issues”. Under “policy pathways”, the Insitute addresses: “Which policy interventions (education, sanitation, pollution control, health care, etc.) would lead to equal progress in the Human Development Index (HDI) compared to a “conventional” increase in per-capita” income, while causing less GHG emissions?…We recognize that the HDI is now a pervasive index and one that resonates well with policy makers.”
Seems quite simple what is going on here. The team needs larger error bars to avoid current climate behavior proving them wrong. Higher uncertainty keeps them from being provably ruled out, while increasing how high/how much catastrophic warming they can predict even in the face of cooler temperatures.
Fortunately, models, computational or not, are not a source of empirical data. So, if models cannot estimate forcing properly, that is because the models are wrong. Simple as that. The sad thing is, upon reading the abstract and conclusion, that modellers seem to forget that simple Science 101 lesson. Do they give away PhDs at the county fairs lately?
CO2 continues to rise, lagging behind falling world temperature, but now we have an interesting test.
The waminstas have been praying for El Nino to start up and get temperatures back to 1998 levels.
Gaia must have been listening. Looks like its on again, but bound to be weak because of a negative PDO. Can’t honestly say.
Is there anything novel here?
I think it is well known in the small model community that if you feel free to scale the forcing you get a range of CS values that prvide a best fit, and if you assume a lightweight ocean (and I think that diffusivity of 0.55cm^2/s gives such an ocean), there is little to discriminate between high-end value of CS.
Assuming other values for diffusivity would move the low point but the range will always be open to very high values but constrained for very low values of CS.
I have some other concerns, regarding the temperature sets used. They say:
“Data include atmospheric concentrations of CO2, CH4, and N2O and global-mean surface air temperature change each year (from year 1750 to 2000).”
I can not find a reference to the supporting material so I do not know where the temp record comes from but to model the heat uptake by the ocean you need separate land and ocean temps, perhaps someone can point me at the supporting materials.
This “could” invalidate:
“Figure 2.1 showsthat low climate sensitivity is not supported even with the missing forcing approach because the missing forcing goes beyond its 2σ uncertainty range to explain the warming in the late 20th century.”
Low end values of CS are constrained by getting the ocean uptake rright. Values for their models uptake should be constrained by measured OHC values. It would be nice to see their values.
I find the following comment a little bizarre:
“Figure 2.2 demonstrates that high climate sensitivity is not acceptable with the forcing scaling approach, which results in excessively strong cooling after large volcanic eruptions in the 19th century.”
The abstract does not give that impression. It seems that they are actually ruling high values out but I do not know what they can mean by “acceptable”.
Also they say:
“The forcing scaling factor is estimated to be 0.045, 0.999, 1.214, and 1.398 in the forcing scaling-based inversions with climate sensitivity of 1, 3, 5, and 10°C, respectively.”
Well this seems upside down to me and I suspect that 0.045 is a typo for 0.45. But who knows.
Alexander Harvey
To evoke ‘uncertainty’ in order to realise the ‘possibility’ of a ‘predicted’ outcome is utterly shameless……………..but that is what climate science has been reduced to.
ACHTUNG!
Alle touristen und non-technischen lookenpeepers! Das machine is nicht fur fingerpoken und mittengrabben. Is easy schnappen der springenwerk, blowenfusen und poppencorken mit spitzen sparken.
Das machine is diggen by experten only. Is nicht fur gerwerken by das dummkopfen. Das rubbernecken sightseeren keepen das cottenpicken hands in das pockets. Relaxen und watchen das blinkenlights.
Who is this turkey ?
I’m calling BS on this incoherent babble.
Each sentence is worse than the previous sentence. Totally devoid of meaning.
H.R. (02:42:26) :
Anyhow, I’m 100% certain that once the big meteor hits, it won’t matter how sensitive the climate is to CO2.
Ah, but NASA will see it coming, and Bruce Willis, Big Al and Arnie will fly up and save the world by wedging Al in the hole they’ve drilled with the nuke at the bottom to make sure the energy is directed into the frozen heart of the meteor.
And if that fails Jim Hansen will adjust the trajectory data and it’ll miss us.
Oh. Wait a minute.