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.
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kcrucible: “This paper jives with my comment about the last one.”
jibes http://dictionary.reference.com/browse/jibes?db=dictionary
It does not appear that most commenters have actually read the paper–email me cloehle at ncasi dot org if you want a reprint.
As to bias in the instrumental data, I discuss that this would lower my estimate of sensitivity. As to going back 15,000 years–I do not claim that my model captures such long cycles, but only that it captures the bulk (not every detail) of the cycles of the period analyzed (150 yrs). My result agrees with most of the empirical sensitivity estimates. As to the whole process of estimating sensitivity being “unscientific” I do fear that there is a risk but the question is too important to do nothing–science is an iterative process and can’t wait until all factors can be perfectly accounted for. As to the validity of subtracting the natural cycles–if natural cycles gave part of the warming in the 1980s-1990s and part of the pause, why can we not subtract the natural cycles to see what is left over? To Tisdale’s question–no I did not use the PDO index directly but long-term data indicating a 60 yr cycle exists. If you don’t believe in cycles at all, then you are free to ignore this paper.
Vuc’ says: http://i.telegraph.co.uk/multimedia/archive/02983/gods-face0_2983566k.jpg
I didn’t notice the file name first time round. Cool pic. Looks like a renaissance painting 😉
“God” = Jehovah = Jove = Jupiter. ( aka , Zeus. )
Chief honcho or various pantheon’s and god of sky and thunder ( aka ‘climate’).
===
Now taking a more modern approach to astronomy, a few numbers ( best values, should be accurate to 9 or 10 sig.figs ):
pSaros= 18.0310284658705
pApsides=8.85259137577002
days_per_year = 365.25636
print 2/(1/pApsides+1/pSaros)
pApSaros=11.8749876715626
That is very, very close to Jupiter’s sideral orbital period. (fixed stars).
pJ= 4332.589 / days_per_year # = 11.861775658061
Now looking at how long these cycles take to drift in phase and come back into phase:
print 2/(1/pJ-1/pApSaros) = 21322 years
http://en.wikipedia.org/wiki/Apsidal_precession
“These two forms of ‘precession’ combine so that it takes over 21,600 years for the ellipse to revolve once relative to the vernal equinox” [Note this is the Earth’s apsides (perihelion/aphelion) now, not the the lunar perigee cycle. ]
Now I think that calculation shows that Jupiter is the primary cause of the precession of the terrestrial and lunar apsides ( which as the the most massive planet by far, would not be too unexpected ).
Lunar distance from perigee to apogee varies by about 15%, that is 45% in variation in tidal force. Jupiter is what is driving that eccentricity and how it’s line of action varies through time.
So while the tidal force of Jupiter is too weak to have a direct effect it does have an effect on Earth systems via the moon.
By Jove !!
A few comments.
1) I suspect 1950 is used because that is when the IPCC states humans started to have a major impact. Hence, anything before that time would not be relevant.
2) It looks to me like this is an attempt to put a ceiling on the possible warming, not to claim they have the complete answer. This is extremely valuable in dealing with alarmists. The alarmists are still pushing 3-4C increases by 2100. If that is 1-2C (including the warming that has already occurred) then they are left with nothing on which they can base their demands for emission reductions.
3) This is almost identical to a computation I did a couple of months using the RSS satellite data as a source (TCR = .96C).
4) The fact that solar is probably some part of this number should not be a big concern at this time. First, we need to get some reality back into the situation. Only then will others be open to looking any deeper. I think this paper is a good step in that direction. It takes the “C” out of CAGW.
“(…) leaving a linear warming trend identified as an anthropogenic signal.”
Exactly. The AGW hypothesis in a nutshell. Assume as a premise that more atmospheric CO2 will lead to global warming. Find a warming signal. Assume it’s because of more atmospheric CO2. The argument has come full circle.
This is truly all they’ve got! And they just don’t see it themselves …
“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 (…)”
Hmm. A couple of pretty important details apparently passed them by. 1) The PDO is not a periodic TEMPERATURE oscillation. And 2) the AMO represents North Atlantic SSTa DETRENDED.
Craig Loehle says:
July 23, 2014 at 6:54 am
====
Thanks Craig..
NONE of the general global temperature rise since the 50s (actually confined to the 25-year period 1976-2001) is because of any increase in atmospheric CO2. There is no such thing as a ‘climate sensitivity’ to CO2.
richard verney says:
July 23, 2014 at 6:17 am
“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.”
Thanks RV. Is there any worthwhile evidence to challenge this? Face it, CO2-driven ‘CS’ is 9/8 of bugger all. ‘Lost in the noise’ is exactly right.
‘Experts’ are faffing around pretending tiny, miniscule margins in CO2 concentrations are significant to temps on a planet-scale level. Ancient history all the way up to the current 17 year pause / humiliation shows that is outright rubbish. The only thing preventing legions of beneficiaries from acknowledging as such is their pride, hubris and pay cheque.
richard verney, you write “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.”
We agree. However, the claims of proper values of CS from estimates have been around so long that few people, including Craig Loehle, any longer bother to stop to wonder whether they are, in fact, writing complete nonsense, which they are.
I have been fighting this battle for several years, particularly on Climate Etc. With zero success. The idea that estimates are the equivalent of measurements is now so ingrained in the “science” of CAGW that it is almost impossible to remove it. I hope you will help me try. I feel like a lone voice, crying in the wilderness, particularly when the likes of Steven Mosher claim that there is no categorical difference between estimates and measurements..
It would be fantastic if Craig were to read our comments, and endorse what I/we are saying. I can live in hope, even if I die of despair.
Isn’t 1c around what would be expected from CO2 warming + no feedbacks?
Yup. The basic lukewarmer position.
Dr. Brown wrote:
“This is just a more complex form of numerology[…]”
Dr. Brown, would you not agree that if the historical data is too sparse to be meaningfully analyzed in the frequency domain, then it is too sparse to conclude that multidecadal warming is NOT cyclic?
Dr. Loehle wrote:
“As to the whole process of estimating sensitivity being “unscientific” I do fear that there is a risk but the question is too important to do nothing–science is an iterative process and can’t wait until all factors can be perfectly accounted for.”
FWIW, that sounds exactly right to me.
It appears that the author is assuming:
1. that there are 60/20 year climate cycles, that persisted from 1850 to present
2. that the 1850 to 1950 period warmed due to natural causes
3. that any increase in warming post 1950, above the 1850-1950 rate is anthropogenic.
With these assumptions the author is able to get a reasonably good fit to observed temperature. However, it could well be that this fit is simply an accident. If not, then the model should have predictive value going forward.
It would be instructive to show what the model shows outside the 1850-2010 time frame.
They don’t know what the ocean oscillations do, so they don’t know how to subtract them from the observed temperature. Sure, they can see temperatures going up and down over 100 or so years, but they don’t know how much is ocean oscillation and how much is something else. On top of that, they assume that the cycles are identical (just look at tides or seasons or the solar cycle to see how absurd that idea is). But they go ahead and do the subtraction anyway. Then they assume that what’s left is all caused by CO2. Then they report the result to 3 decimal places (1.093). It’s a joke. But it’s no laughing matter that this is the depth to which a supposed branch of science has sunk.
Allan MacRae says:
“BUT:
1. There are negative feedbacks, ECS, if it exists at all , is much less than 1C. Say ~~0.2C.
…
P,S, Greg Goodman – good comments here and on another thread. Good man. 🙂
”
Thanks.
What is more, volcanic forcing is now _scaled down_ to hide the presence of the strong, topical, negative feedbacks.
Back in 1992 Lacis et al ( which included Hansen ) in a boringly, methodical paper derived an AOD scaling of 33 to convert to W/m^2
A few years later they reduced that to 21 to improve agreement with model output.
http://climategrog.wordpress.com/?attachment_id=884
That scientists can still give serious regard to “climate sensitivity” when the last 17 years shows none shows how theory becomes fact and fact becomes ignored in this world of climate science.
When one considers that the late warming trend circa 1977-97 was due to increased insolation, not CO2, this “climate sensitivity business becomes farcical.
ferdberple says:
July 23, 2014 at 7:23 am
It appears that the author is assuming:
1. that there are 60/20 year climate cycles, that persisted from 1850 to present
2. that the 1850 to 1950 period warmed due to natural causes
3. that any increase in warming post 1950, above the 1850-1950 rate is anthropogenic.
There are thus four free parameters in this curve fitting exercise. “With four parameters I can fit an elephant” said John von Neumann. [“and with five, I can make him wiggle his trunk”].
The temperature rise, likely in whole, is I think due to discharge/recharge of heat stored in oceans. There is tremendous lag involved in discharge and recharge and is significantly driven via cloud patterns and oscillations related to shifts in large scale climate regimes. This means that in somewhat chaotic fashion, we can experience heat discharge over fairly long periods of time, leading to step increases in global temperatures. We can also experience, during that same time, a lack of recharge sufficient to sustain that rise in the long haul, eventually leading to a temperature pause followed by a fairly long period of declining temperatures. If the clouds enter into a clear sky regime, we can once again look forward to a recharged ocean and the long step wise period of increasing beneficial warmth.
What is unlikely to happen is a long period of stable global temperature where the stored energy is kept at a fairly constant level through periodic and fairly equal discharge/recharge events. My sense is that the normal course of events is somewhat biblical, IE periods of plenty interspersed with periods of suffering.
So I continue to wait for models that demonstrate how atmospheric systems lead to these herky jerky discharge/recharge events of life-giving heat wholly natural in process.
There’s a typo in the title itself, it should read:
New paper finds transient doubling sensitivity of CO2 to temperature change is about 1°C
“2) It looks to me like this is an attempt to put a ceiling on the possible warming, not to claim they have the complete answer. This is extremely valuable in dealing with alarmists. The alarmists are still pushing 3-4C increases by 2100. If that is 1-2C (including the warming that has already occurred) then they are left with nothing on which they can base their demands for emission reductions.”
Yes, I agree. Getting this published is a step in the right direction. But like I said at this pace it will take 10y to before anyone apart from Lindzen gets anywhere a realistic value.
However, I think we’ve reached a ‘tipping point’ now, hopefully things will accelerate and the AGW myth will “collapse” as quickly as Thwaite’s glacier is about to do 😉
These comments remind me of the quote attributed to Winston Churchhill – “Democracy is the worst form of government, except for all the others.”
This paper may still be full of guesses and assumptions that may turn out to be false, but it has less of them than the models and theories used by the IPCC and the warmest community. It realistically indicates a climate sensitivity to a doubling of CO2 of about 1 degree C, which certainly fits the observations better than those other models.
We are a contentious lot, and are prone to nit-picking. That is good for science, but not for policy discussion. I would rather show support for a paper that is at least more accurate AND would argue that CO2 is beneficial; with no requirement for regulation, than dis the paper as being ‘still wrong’.
Once the backwards notion that we must ‘reduce our carbon emissions to save the planet’ is dead and buried, I don’t care how much quibbling takes place over the science. We can argue over hundredths of a degree, minute albedo changes, magnetic field fluxes and ocean cycles until the cows come home, but let’s support the good science that undermines the regulation insanity, even if it is not yet perfect!
This paper may be the worst, except for all those papers that support the warmest agenda.
LS: “There are thus four free parameters in this curve fitting exercise.”
two harmonics ( 3+3 ) plus two linear ( 2+1 ) = 9
How many parameters does it take to model the movement of Focault’s pendulum in a museum in Paris?
Is global temperature variation more or less complicated than a pendulum?
Von Newman’s comment is intended as a caution , not an all purpose smart remark.
Yes, ~ 1 deg for doubling is what it will turn out to be. It is actually fairly obvious if you look at the data objectively.
Greg Goodman says:
July 23, 2014 at 7:50 am
Von Newman’s comment is intended as a caution , not an all purpose smart remark.
So was mine, so was mine
The equation that incorporates the equilibrium climate sensitivity as its proportionality constant conveys no information to a policy maker about the outcomes from his or her policy decisions. This conclusion follows from the lack of observability of the equilibrium temperature and the definition of the “mutual information” as the measure of the intersection between observables. Also, The existence of an anthropogenic signal violates the prohibition on superluminal speeds in the theory of relativity, superluminal speeds being required for this signal to carry information to a policy maker about the outcomes from his or her policy decisions.
I sometimes weep for my species.
No need to.
Science: Few aggravated photons kicked out by a few agitated electrons, when reach human retina extort their revenge on more electrons, making the ‘fatty lump’ sitting in the said ‘species’ sculls, construct what some may refer to as a reality.
Then they build most complex electronic observing, calculating and displaying devices, again using more agitating electrons to observe and evaluate this so called reality.
Pseudoscience: in a relaxed and hustle free manner bypasses all tiresome intermediate stages and lets the ‘fatty lamp’ do what is meant to do.
One way or the other, any difference is entirely subjective.