A new paper published in Ecological Modelling finds climate sensitivity to doubled CO2 concentrations is significantly lower than estimates from the IPCC and climate models which “utilize uncertain historical data and make various assumptions about forcings.” The author instead uses a ‘minimal model’ with the fewest possible assumptions and least data uncertainty to derive a transient climate sensitivity of only 1.093C:
“A minimal model was used that has the fewest possible assumptions and the least data uncertainty. Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal. This estimated rate of warming was related to the fraction of a log CO2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C). It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.”
Otto et al find equilibrium climate sensitivity [over the next several centuries] is only ~1.3 times greater than transient climate sensitivity, thus the estimate of 1.093C transient sensitivity could be associated with as little as 1.4C equilibrium sensitivity, less than half of the implied IPCC central estimate in AR5 of ~3.3C.
Moreover, this paper does not assume any solar forcing or solar amplification mechanisms. The integral of solar activity plus ocean oscillations explain ~95% of global temperature change over the past 400 years. Including potential solar forcing into the ‘minimal model’ could substantially reduce estimated climate sensitivity to CO2 to a much greater extent.
- Empirical estimates of climate sensitivity are highly uncertain.
- Anthropogenic warming was estimated by signal decomposition.
- Warming and forcing were equated in the time domain to obtain sensitivity.
- Estimated sensitivity is 1.093 °C (transient) and 1.99 °C (equilibrium).
- Empirical study sensitivity estimates fall below those based on GCMs [Global Circulation Models].
Abstract
Climate sensitivity summarizes the net effect of a change in forcing on Earth’s surface temperature. Estimates based on energy balance calculations give generally lower values for sensitivity (< 2 °C per doubling of forcing) than those based on general circulation models, but utilize uncertain historical data and make various assumptions about forcings. A minimal model was used that has the fewest possible assumptions and the least data uncertainty. Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal. This estimated rate of warming was related to the fraction of a log CO2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C). It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
They needed a computer to draw a straight line??
“Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal.”
It seems they jumped to an unwarranted conclusion. Firstly, as we all know, there is a warm bias in the temperature record, to the tune of as much as 50%. Secondly, and as they mentioned, no solar forcing was included since that is still a grey area. Thirdly, and the knockout blow is the fact that the warming stopped some 17 years or more ago, and we appear to be cooling now.
Even though this is a vast improvement over ipcc pseudoscience, it is still nonetheless pseudoscience. It still claims to see an anthropogenic signal, but it’s just a ghost, just not as scary a ghost as the ipcc’s.
rgb,
Exactly!
Early CO2 peak concentrations (pre 1950) are almost certainly understated because of smoothing during ice closure and CO2 loss during sampling. Surface instrumnet warming is clearly overstated. Thus this study would tell us only that climate sensitivity to CO2 doubling is close to zero if the input data is corrected.
Well, at least “about 1 degree” is better than “over 2 degrees”.
/grin
rgbatduke says: July 23, 2014 at 5:28 am
What could go wrong? Frequency 🙂
If the pause continues for another few years, there will almost certainly not be an AR6.
As I commented some years ago, as the pause lengthens, there will be an ever increasing number of papers showing ever decreasing climate sensitivity figure.
The range for climate sensitivity has not been narrowed in 35 years notwithstanding billions of dollars thrown on this ‘science’ and as Russ R. says: July 23, 2014 at 5:17 am, there is now no consensus amongst the ‘leading’ climate scientists on this, which after all is the most important issue of all. The lack of consensus is because many of the leading climate scientists recognise that natural variation has been underassessed and observational data now coming in, suggests that climate sensitivity must be below 2.2. They know that if the pause continues (and many are openly saying that there may be no return to warming for a decade or so), that ‘best guestimates’ will lower that figure to less than 1.7, may be even less than 1.5.
If the pause continues, it will not be long before the majority of new papers are showing a range of say 1.3 to 1.8, then 1.2 to 1.7, eventually coming in with ranges of 0.8 to 1.3.
If that happens, AR6 will have to admit that the climate models got it wrong (most will by then have been invalidated having fallen outside the 95% level) and that best estimates for climate sensitivity is not a scarry figure. So I do not expect to see an AR6, especially as some Governments are already getting cold feet, and many Governments have yet to see the backlash that will arise from the needlessly hiked energy costs that are just coming home to roost.
Climate sensitivity is not a theoretical construct, but is the real world response to CO2 in the atmosphere as it plays out in the climate system of planet earth. This can only be ascetained by observational data.
But claims that we can assess climate sensitivity are unscientific. I do not accept that one can even begin to assess climate sensitivity from observational data, until you are in a position to eliminate in its entirety natural variation, and that would require us to fully understand what natural variation is, what it consists of, each and every constituent forcing, their upper and lower bounds, and how it plays out over the years etc.
Presently, there is no hard data that confirms that there is any climate sensitivity to CO2, if there is a signal it is lost in the noise. I am with Gregg, that it is likely once everything has panned out that CO2 sensitivity is sod_all +/- 50% How long it will take ‘them’ to admit that, is more debatable and will no doubt be influenced by whether we see a period of cooling over the coming years and decade. Cooling of just 0.1 to 0.15 degC would quickly tilt the table.
Of course, I do not know how long the pause will continue, and when there is a change whether this will be up or down, but if it is down, I consider it likely that the stack of cards will quickly fall.
“leaving a linear warming trend identified as an anthropogenic signal. ”
Looking at the geologic record of climate oscillations over the past 15,000 years, it is readily apparently that natural oscillations completely dwarf any CO2 effect. Warming of 20 F in less than a century occurs several times and warming of 5-10 F repeats many times, all at very low atmospheric CO2. At present we really don’t know the proximate cause of these multiple, very abrupt, high intensity periods of warming (and cooling). Obviously, CO2 is not a factor in these climatic warming episodes, so how can we ascribe something ‘left over’ in models that don’t include a solar component? The GISP2 Greenland record shows that temperatures in Greenland were 2.5-5.5 F warmer for almost all of the past 10,000 years–certainly not driven by CO2.
Until we have a better understanding of what really drives these abrupt, intense climate changes, as well as longer term changes, how can we assign any value to CO2 sensitivity?
“urederra says: July 23, 2014 at 5:50 am re: transient climate sensitivity of only 1.093C:
Three significant figures, LOL.”
That’s FOUR significant figures, IMHO.
Meanwhile, almost 20 years ago…
November 16 1995
Dr. MICHAELS. I should say l am Associate Professor of Environmental
Sciences, and at 4:00 o’clock today , I will be given my promotion
seminar, so hopefully that will cgange in a very short period.
Controversy surrounding the issue of global warming is a classic
example of what I think is the normal and creative scientific tension
that exists between those who formulate models or hypotheses and
those who evaluate such models with observed data.
Unfortunately, this issue has evolved in a highly politicized climate.
For the last decade, a community of scientists, often referred
to as a small minority, has argued that, based upon the data on
climate change, the modeled warming was too large, and therefore
any intrusive policy would not be based upon reliable models of
global warming.
This view has been cast in a very negative political light, which
has had a chilling effect on scienti?c free speech.
At the same time, testimony has repeatedly been given in front
of this Congress that the modeled and observed temperatures were
broadly consistent. This view has been amply rewarded. Nonetheless,
these two views have never been reoonciled scienti?cally.
The early suite of models produced an average warming of about 4
degrees celsius for doubling carbon dioxide, and the data suggested
a much lower number, about 1 to 1.5 degrees of additional warming.
The most important development in the last two years is that it
is now acknow edged that the community that argued for the lower
numbers appears more likely to be correct. Moreover, it is apparent
that the climate model that was most heavily cited by the United
Nations in a special 1992 supplementary report on climate change
which was prepared specifically to provide technical backing for the
framework convention on climate change, it is now known that that
model was known to be making large errors in the forecast of current
temperature at the time of the adoption of the framework convention.
And yet this never entered into the debate surrounding that
issue.
These observations strongly suggest that the scientific review
process that bases these international agreements has been highly
flawed, or there may have simply been omissions in communicating
to responsible individuals how large the errors in these calculations
were.
rgbatduke says:
July 23, 2014 at 5:28 am
Thank you doctor! Laughter is the best medicine.
If I “bold face” selected verbiage in the following quoted commentary, to wit:
————
“Abstract
Climate sensitivity summarizes thenet effect of a change in forcing on Earth’s surface temperature.
Estimates based on energy balance calculations give generally lower values for sensitivity (< 2 °C per doubling of forcing) ………..
…….. than those based on general circulation models, but utilize uncertain historical data and make various assumptions about forcings.
A minimal model was used that has the fewest possible assumptions and the least data uncertainty.
Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal.
This estimated rate of warming was related to the fraction of a log CO2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C).
It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.”
=====================
Then me thinks the above is little more than “neo-science fiction” criticizing itself.
Richard V, there will not be an increase in temps beyond this solar “mini-max”. Once the Sun is definitely into the downhill slide towards solar minimum, cooling will become obvious, even to the most diehard warmist. Of course Al Gore & Co will be the last ones to notice, as the warmists do not pay attention to reality whatsoever.
Jim Cripwell says:
July 23, 2014 at 5:49 am
/////////////
Your comment was not up when I prepared my comment. The last post up was rgb’s usual useful insight.
You are absolutely spot on. I had started using the fra** word to describe such claims, but then decided better of usiing such inflamable language, and decided to make my comment (But claims that we can assess climate sensitivity are unscientific) more neutral..
I do not see how claims about assessing climate sensitivity can be conducted with a straight face. It is a farce, pure and simple. It is not physics, it is not science, well at least not of the type that I was taught.
“The early suite of models produced an average warming of about 4
degrees celsius for doubling carbon dioxide, and the data suggested
a much lower number, about 1 to 1.5 degrees of additional warming.”
That’s testimony to congress in 1995. What has changed?
ehhhhh….this paper is also wrong.
There is no man made warming.
If it is there it is so small that man cannot even measure it.
Note the graph on the bottom of the third table, obtained from a random sample.
http://blogs.24.com/henryp/files/2013/02/henryspooltableNEWa.pdf
(minima is supposed to rise when there is more GHG)
Must be natural
Cannot be not-natural.
If there were any man made global warming the graph should show less Rsquared something less than 1.
Oh happy day….
Eric Worrall says:
“Isn’t 1c around what would be expected from CO2 warming + no feedbacks?”
No, it is what is expected assuming net zero feedbacks. Big theoretical difference.
Considering how completely inaccurate positive feedback assumptions have been,
it is almost intellectually imperative that only empirical data be used.
rgbatduke says:
July 23, 2014 at 5:28 am
You missed out LMAO and LMFAO.
richard verney says:
July 23, 2014 at 6:17 am
Climate sensitivity is not a theoretical construct, but is the real world response to CO2 in the atmosphere as it plays out in the climate system of planet earth. This can only be ascetained by observational data.
================
How can you say it is a “real world response” and then tell us, “Presently, there is no hard data that confirms that there is any climate sensitivity to CO2, if there is a signal it is lost in the noise.” What moves it from “theoretical” to “real” in your mind?
“urederra says:
July 23, 2014 at 5:50 am
Apparently the error of Bootstrap algorithm could be of the size of Alaska, maybe.”
I thought the area in question was only 200,000 sq km…or about the size of Nebraska.
But…wouldn’t a sensitivity of around 1 C per doubling mean that we’d need to hit 600-700 ppm CO2 to see much of anything?
The models went off the rail with their water vapor fudge factor. That factor is based on two sources of additional water vapor being added to the atmosphere: 1) evaporation from a warming ocean due to additional heating from downwelling longwave infrared radiation, and 2) evaporation from land surfaces (IE soil, etc) from extra warming due to the same anthropogenic process. Both of these processes do indeed take place. The ocean surface does in fact add water vapor to the atmosphere via evaporation. And land surface send moisture into the air as well. But what amount of watts does it take to do that to each kind of surface and does the very tiny amount of watts in just the anthropogenic portion of CO2 cause a measurable increase in this noisy otherwise natural process?
The physics behind this anthropogenic evaporation adding to natural atmospheric water vapor cannot be demonstrated under lab conditions sufficient to simulate anthropogenic additions to ocean and land surface evaporation. So it became a fudge factor in order to get the models to match the segment of the temperature series used to tune the damned things. On top of that, they had to add aerosols to tone it down, as if Earth actually provides a steady stream of aerosols in a nice neat package.
The error is in the models and it is such a glaring 1st grade error I remain gobsmacked that it continues to rule grant applications, research journals and political policy discussions.
After 160 + years of the industrial revolution, we’ve doubled CO2 how many times?
“Coach Springer says:
July 23, 2014 at 6:48 am
After 160 + years of the industrial revolution, we’ve doubled CO2 how many times?”
What is ‘never’?
Bob Weber says:
July 23, 2014 at 6:29 am
///////////////
You might be right.
I am one of those people who can see some similarity between solar activity and temps, but not necessarily full correlation, and, of course, correlation does not mean causation. The processes involved in how changes in solar activity may affect Earth’s climate are not well known and understood. I see no empirical observational data that shows that CO2 drives temperatures, and my gut (that unscientific barometer) tells me that the sun is likely to be a more significant player than CO2.
Predicting the future is always difficult. We do not know whether the sun will enter a prolonged period of quiet activity (although I would not be surprised to see that happen based upon available data), still less what that will do, and why, on planet Earth. The next decade or so could be interesting, and it is likely that we will learn a lot. If we do see a quiet sun, although many questions will be raised, it is likely to settle some of the debate.
Whilst the science brings me to tears, my biggest gripe is the political response to all of this. It is complete madness, since for the main part, the policies to do nothing to reduce gloabl emssions of CO2, and are accordingly entirely futile even if you consider CO2 emissions to be a problem.
Sooner or later the truth will come out, and the science will sooner or later reveal the truth (whatever that will be even if it is that AGW is real and is to some extent problematic). But it is the mad mad politically driven response which is inflicting real damage to the people, their life styles, their jobs and the economy, as well has holding back development and a decent life for those living in the developing world and 3rd world. These pople are owed better.
I do not like the cold, but I do hope to see some cooling merely to get some sanity back in what to do in an ever changing world, ie., adaption over mitigation. lets spend our money on doing something good, rather than wasting it on futile gestures.
Don Easterbrook makes the most sense, when he writes:
“Looking at the geologic record of climate oscillations over the past 15,000 years, it is readily apparently that natural oscillations completely dwarf any CO2 effect. Warming of 20 F in less than a century occurs several times and warming of 5-10 F repeats many times, all at very low atmospheric CO2. At present we really don’t know the proximate cause of these multiple, very abrupt, high intensity periods of warming (and cooling). Obviously, CO2 is not a factor in these climatic warming episodes, so how can we ascribe something ‘left over’ in models that don’t include a solar component? The GISP2 Greenland record shows that temperatures in Greenland were 2.5-5.5 F warmer for almost all of the past 10,000 years–certainly not driven by CO2.
“Until we have a better understanding of what really drives these abrupt, intense climate changes, as well as longer term changes, how can we assign any value to CO2 sensitivity?”