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« The IPCC versus Stevens | Main | Hague's chosen fruitloop »

Climate sensitivity takes another tumble

Over at Climate Audit, Nic Lewis reports on the publication of a very important paper in Journal of Climate.

Bjorn Stevens has created a new estimate of the cooling effects of pollution ("aerosols") on the climate. Readers will no doubt recall that to the extent that aerosol cooling is small the warming effect of carbon dioxide must also be small so that the two cancel out to match the observed temperature record. Only if aerosol cooling is large can the effect of carbon dioxide be large.

Stevens' results suggest that the aerosol effect is even lower than the IPCC's best estimates in AR5, which were themselves much lower than the numbers that were coming out of the climate models. He also suggests that the number is less uncertain than previously thought. This is therefore pretty important stuff. 

Stevens chose not to calculate the effect on climate sensitivity but, being a helpful chap, Nic Lewis has done so for us, plugging the new numbers into the equations he recently used to calculate a decidedly low estimate of climate sensitivity and transient climate response based on the AR5 estimates. The effects, particularly on the upper bounds, are startling:

Compared with using the AR5 aerosol forcing estimates, the preferred ECS best estimate using an 1859–1882 base period reduces by 0.2°C to 1.45°C, with the TCR best estimate falling by 0.1°C to 1.21°C. More importantly, the upper 83% ECS bound comes down to 1.8°C and the 95% bound reduces dramatically – from 4.05°C to 2.2°C, below the ECS of all CMIP5 climate models except GISS-E2-R and inmcm4. Similarly, the upper 83% TCR bound falls to 1.45°C and the 95% bound is cut from 2.5°C to 1.65°C. Only a handful of CMIP5 models have TCRs below 1.65°C.

Remember folks, the IPCC's official upper bound is 4.5°C, but Stevens' results suggest that ECS can't be above 1.8°C.

Jim Hansen, Bob Ward, Kevin Trenberth, Michael Mann and Gavin Schmidt, your climate alarmism just took one helluva beating.

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Reader Comments (33)

Climate sensitivity looks to be effectively zero, perhaps, plus/minus the error.....

Mar 19, 2015 at 11:01 PM | Unregistered Commenterdodgy geezer

When is anyone influential going to take this seriously?

Mar 19, 2015 at 11:06 PM | Unregistered CommenterTinyCO2

Terrific job helping, Nic Lewis! Bravo!

Very interesting analysis Bjorn Stevens, thanks!

Mar 19, 2015 at 11:09 PM | Unregistered CommenterATheoK

My own intuition has long been that “climate sensitivity” is a load of bunkum, anyway. It comes to something when intuition trumps science.

Mar 19, 2015 at 11:13 PM | Registered CommenterRadical Rodent


...When is anyone influential going to take this seriously?... don't get to BE influential if you take this seriously. Don't you know how many jobs are at risk if the CO2 scare collapses?

Mar 19, 2015 at 11:30 PM | Unregistered Commenterdodgy geezer

So if someone had used a better calculator 30 years ago, we wouldn't be in this mess now.

Can Trenberth now be stood down? No missing heat to look for

Can Mann retire his hockey stick, as it was never fit for purpose? Save a bit on legal fees too.

Can Ward now turn off his office air conditioning, without getting overheated?

Can Hansen go home on a death train?

Can Schmidt not return to the UK?

Will they all blame Aarhenius for not using a solar powered, metric slide rule?

Will the BBC blame the partial eclipse on global warming?

Mar 19, 2015 at 11:58 PM | Unregistered CommenterGolf Charlie

Tiny CO2 / Dodgy Geezer "When is anyone going to take this seriously?"

Dunno, when they are jailed for fraud?

Mar 20, 2015 at 12:04 AM | Unregistered CommenterGolf Charlie

Is there any chance that Nic Lewis once had a cup of coffee, from a friend who had a part time job, at a petrol station, over 20 years ago?

I am sure that tax payer funds are already being burnt, in a search for this most important piece of information.

Mar 20, 2015 at 12:23 AM | Unregistered CommenterGolf Charlie

My coal fired Amstrad PCW climate model still says sensitivity=Sweet FA

The GWPF. Warmism for Dummies.

Mar 20, 2015 at 1:33 AM | Unregistered Commenteresmiff

My favourite memory of the medieval warm period was a lovely discussion with a few soothsayer chums over a cheeky, little bottle of Trondheim Chardonnay in Lerwick. One of them said 'it's bloody hot for the Ides of March, 32 degrees. Why the hell is that ?

One of the former Vestal Virgins said 'we are all going to die, for sure, this is a tipping point'. We reckon it has to do with two headed sheep. We are getting 2.1 per thousand in Siberia. Every 0.4 two headed sheep means an extra 1 degree in global temperature. The Delphic Oracle says 0.1, but they are Greek communists, they would !

What matters is that we can all go along to the House of Lords with Nicholas Didley and agree that two headed sheep are changing the climate. For sure.

Mar 20, 2015 at 2:18 AM | Unregistered Commenteresmiff

Bottom line is, aerosol physics/chemistry is heterogeneous-phase stuff. They know far less about it than anything else. By definition.

That ought to scare them witless, and to be fair, is probably why it has always been afforded such large uncertainties by the IPCC.

Mar 20, 2015 at 3:11 AM | Unregistered Commentermichael hart

" It comes to something when intuition trumps science."

I honestly still don't understand how the H20/CO2 radiation effect is supposed to warm the surface in the real world when radiation is the dominant factor in regulating temperature in the first place. Intuition says the water cycle and convection are the dominant factors, not forgetting the sun which dumps all the energy onto the Earth in the first place.

In the tropics at the moment and see the water/cloud cycle in action virtually every afternoon.

Mar 20, 2015 at 4:02 AM | Unregistered CommenterRob Burton

Golf Charlie: "if someone had used a better calculator 30 years ago, we wouldn't be in this mess now."

Actually, 30 years ago they had a decent guess at sensitivity. From a recent comment of mine (slightly edited) at Climate Etc.,

William Nierenberg chaired the 1983 NAS “Carbon Dioxide Assessment Committee” report. Referring to the 1979 Charney report’s ECS range of 1.5 to 4.5 K/doubling, they wrote: “Results of most numerical model experiments suggest that a doubling of CO2, if maintained indefinitely, would cause a global surface air warming of between 1.5°C and 4.5°C. The climate record of the past hundred years and our estimates of CO2 changes over that period suggest that values in the lower half of this range are more probable.”

Unfortunately, the IPCC chose to focus more on the models' responses rather than the climate record. I express guarded optimism that the models will be "toned down" to diverge less from the observations, and their sensitivity and the observationally-derived sensitivity converge somewhere in the "lower half".

Mar 20, 2015 at 4:07 AM | Registered CommenterHaroldW

Mar 20, 2015 at 2:18 AM | esmiff

And you stayed up just to write that? Oh dear. You poor man.

Mar 20, 2015 at 4:27 AM | Unregistered CommenterJeremy Poynton

Good job our politicians were smart enough not to listen to the doomsayers, and embark on some ludicrous change of energy policy.

Mar 20, 2015 at 5:20 AM | Unregistered CommenterAnything is possible

Doesn't the REAL WORLD show that climate sensitivity to increasing CO2 is quite low ?
18 years of key indicators failing to show signs of accelerating change towards doom, whilst at the same time the amount of CO2 emitted has increased greatly.

Mar 20, 2015 at 6:45 AM | Registered Commenterstewgreen

No matter what the sensitivity, even if it is zero or negative (or as RR concludes), the politicians will still need to shut down the economy to stay below the 2C tipping point and to gain control of the world.

We are slowly creeping to the time when the "greenhouse effect" will rightly be declared to be bunkum.

Mar 20, 2015 at 6:51 AM | Registered CommenterPhillip Bratby

The agenda is to get the C02 taxes firmly in place, and govenment spending adjusted to be utterly dependent on them. All ASAP.
That way, if and when CAGW is shown to be illusory, it will be said that as the taxes and controls are a bulwark of policy, they cannot be dropped. Political reality requires that policy be based on illusion.

Mar 20, 2015 at 7:48 AM | Unregistered CommenterTuppence

Mar 20, 2015 at 4:27 AM | Jeremy Poynton

Sorry but they made me smile, the thought of a medieval Ed Davey spouting nonsense like that to nodding donkeys in parliament was quite amusing.

Mar 20, 2015 at 8:55 AM | Unregistered CommenterSandyS

Mar 20, 2015 at 7:48 AM Tuppence

EXACTLY !!! Hence the rush to Paris. It's their next to last chance.

Mar 20, 2015 at 8:57 AM | Unregistered CommenterStephen Richards

From 'The Pleasure of Finding Things Out' by Richard Feynman, with a forward by Freeman Dyson.

When someone says science teaches such and such,he is using the word incorrectly. Science doesn't teach teach it; experience teaches it. If they say to you science has shown such and such, you might ask, "How does science show it -- how did the scientist find out -- how, what, where?" Not science has shown , but this experiment, this effect, has shown. And you have as much right as anyone else, upon hearing about experiments (but we must listen to *all* the evidence), to judge whether a reusable conclusion has been arrived at.

In a field which is so complicated that true science is not yet able to get anywhere, we have to rely on a kind of old-fashioned wisdom, a king of definite straightforwardness. I am trying to inspire the teacher at the bottom to have some hope, and some self-confidence in common sense, and natural intelligence. The experts who are leading you may be wrong.

I believe that we are only at the point in climate analysis of it being "so complicated that true science is not yet able to get anywhere," therefore Rob Burton, Radical Rodent's intuition may well be correct as for all of us the "experts who are leading you may be wrong."

Mar 20, 2015 at 9:23 AM | Unregistered Commentertom0mason

Unfortunately, DECC's scientists will make sure that our politicians are told that these data are icompletely ncorrect - because the science is settled!

Mar 20, 2015 at 9:27 AM | Unregistered CommenterPeter Stroud

Jim Hansen, Bob Ward, Kevin Trenberth, Michael Mann and Gavin Schmidt, your climate alarmism just took one helluva beating.
So maybe now is the time to ask these gentlemen the simple question:
Are you about to move heaven and earth in an effort to debunk these findings or are you prepared to at least consider accepting them and admit that, through no fault of anyone's perhaps, the model output has over-estimated the likely effects of CO2 on climate? Or to put it another way, are you genuine scientists (except Ward, who we know isn't) prepared to let the chips fall where they may, or are you political activists prepared to do and say anything to get your own way?
Simple, no?

Mar 20, 2015 at 9:28 AM | Registered CommenterMike Jackson

Peter Stroud

Exactly. All they are doing is validating the liars, and that is what whoever funds the GWPF is paying for. I'd love Jeremy Poynton tell us what was driving temperatures up during the medieval warm period.

Help !! The sun just disappeared. We're all going to die. The wrath of Jupiter is upon us. A deadly plague will follow within two days.


Mar 20, 2015 at 9:37 AM | Unregistered Commenteresmiff

MJ: an apt analogy would be to see science as piecing together the vast jigsaw puzzle of facts that help to explain the universe. Some pieces can be remarkably similar, so can be placed in the wrong location, others can be very different, yet forced into the picture. We have managed to complete many parts of the picture, though are not yet able to link them all together. What is taking place in climate “science” (and is creeping out to other disciplines) is the forcing of pieces to fit preconceived ideas; many of the “scientists” involved, and the politicians that have latched onto them, are not only quite prepared to lever non-fitting pieces into the picture, but are also happy to create their own.

My own intuition does have precedence; a well-known historical figure also intuitively realised the facts, and broadcast them. His argument fell short when he was asked to prove it. He couldn’t. However, being a truculent sort, he continued to make waves, until his friends in authority got annoyed with him. That’s when the myth took over.

Mar 20, 2015 at 10:41 AM | Registered CommenterRadical Rodent

This issue is the very crux of the matter, and repeatedly it seems every real-world observation is pointing toward very low sensitivity. Embarrassing! Unfortunately that's exactly the opposite of what alarmists are seeking, so expect them to ignore this for as long as it takes to lock in climate policy, by which time it'll be 'too late' or 'not practicable' to change course from existing or newly-made commitments. It just goes to show what an outrageous fraud this whole charade really is.

Mar 20, 2015 at 11:18 AM | Unregistered Commentercheshirered

It isn't about the climate, it isn't about the science. It is politics. UN World Governance, Agenda 21.

Whilst socialists demand world government, they will continue to push the CO2 theme as a means of control. Without energy, we are nothing.

Confronting the MP's will be the only way to change things for the better. Scientists can then argue whether the temperature has gone up 0.25 deg C or 0.5 deg C over 100 years, but if the politicians weren't hijacking the subject, this would be a great scientific discussion, but no real problem.

Mar 20, 2015 at 11:37 AM | Unregistered CommenterMattS

I have just posted this at CA before seeing this thread:

In the "Dual Critique" of the Stern Review, Carter et al., (2006), we referred to Anderson et al., (2003) 'Climate forcing by aerosols - a hazy picture', Science, 300: 1103 - 1104.

We wrote:

"Further, as leading researchers in aerosol science reported in Science, the aerosol forcing is so poorly known that they felt that calculating how much aerosol forcing is need to cancel greenhouse forcing is as good a way of estimating the aerosol forcing as any."

More circularity!

Mar 20, 2015 at 12:36 PM | Registered CommenterDavid Holland

I am not a scientist --- but I do have a little weatherstation which monitors the tempreature outside my kitchen window on the north shore of the Tay estury.
Now all the 'real scientists' tell me that the great red ball in the sky has virtually no effect on world tempreature. All the global warming (which has not happened for 20 years) is due to that nasty gas called Co2.

The following is a non scientific experiment I carried out this morning.
0815 outside temp 08.1C
0830 09.6C
0845 10.2C
0900 10.5C
0915 10.0C
0920 09.9C
0930 09.7C
0935 09.5C
0940 09.3C
0945 09.0C
1000 09.7C
1015 10.5C
1030 12.5C

At about 0935 someone switched off that big red ball in the sky.

As my little weather station cannot measure temp to better than one decimal point, do the real scientists on here consider that I should submit these startling results to the Met Office or the CRU.
I should point out that I am in receipt of a pension from an Oil Major, but would still like to get funding for further research

Mar 20, 2015 at 1:05 PM | Unregistered Commenterpatrick healy

The actual climate record against rising CO2 has been telling us for many decades that sensitivity is effectively nil (though the alarmists didn't want anyone to listen). Now the work of independent climate scientists seems to be gradually converging on this truth!

Mar 20, 2015 at 4:51 PM | Unregistered CommenterNigel

Once again the skeptics are proven to be correct in their questioing of the consensus and justified in resisting the consensus.

Mar 20, 2015 at 10:37 PM | Unregistered Commenterhunter

MattS is right. It isn't about climate (or even about science).

No point in confronting your MP. Rather take your chance on May 7th and hit him where it hurts. Just keep voting UKIP and he will either change his tune or he will be gone .

Mar 21, 2015 at 2:51 PM | Unregistered CommenterDave

The original commentary on “one helluva beating” is in this short YouTube clip:

Mar 22, 2015 at 8:30 AM | Unregistered CommenterDoug Brodie

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