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Lewis on the SciAm article

This article, by Nic Lewis, is crossposted from Climate Audit.

A Scientific American article concerning Bjorn Stevens’ recent paper “Rethinking the lower bound on aerosol radiative forcing” has led to some confusion. The article states, referring to a blog post of mine at Climate Audit, “The misinterpretation of Stevens’ paper began with Nic Lewis, an independent climate scientist.”. My blog post showed how climate sensitivity estimates given in Lewis and Curry (2014) (LC14) would change if the estimate for aerosol forcing from Stevens’ recent paper were used instead of the estimate thereof given in the IPCC 5th Assessment Working Group 1 report (AR5 WG1). To clarify, Bjorn Stevens has never suggested that my blog post misinterpreted or misrepresented his paper.

The article also states, paraphrasing rather than quoting, “Lewis had used an extremely rudimentary, some would even say flawed, climate model to derive his estimates, Stevens said.” LC14 used a simple energy budget climate model, described in AR5 WG1, to estimate equilibrium climate sensitivity (ECS) from estimates of climate system changes over the last 150 years or so. An essentially identical method was used to estimate ECS in Otto et al (2013), a paper of which Bjorn Stevens was an author, along with thirteen other AR5 WG1 lead authors (and myself). Energy budget models actually estimate an approximation to ECS, effective climate sensitivity, not ECS itself, which some people may regard as a flaw. AR5 WG1 states that “In some climate models ECS tends to be higher than the effective climate sensitivity”; this is certainly true. Since the climate system takes many centuries to equilibrate, it is not known whether or not this is the case in the real climate system. LC14 discussed the issues involved in some detail, and my Climate Audit blog post referred to estimating “equilibrium/effective climate sensitivity”.

I sent Bjorn Stevens a copy of the above wording and he has responded, saying the following:

“Dear Nic,

because I have reservations about estimates of ocean heat uptake used in the ‘energy-balance approaches’, and because of a number of issues (which you allude to) regarding differences between effective climate sensitivity estimates from the historical record and ECS, I am not ready to draw the inference from my study that ECS is low. That said, I do think what you write in the two paragraphs above is a fair characterization of the situation and of your important contributions to the scientific debate. The Ringberg meeting also made me confident that the open issues are ones we can resolve in the next few years.

Feel free to quote me on this.

Best wishes, Bjorn”

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Reader Comments (15)

I'm not getting any sense that Stevens thinks that Lewis has misinterpreted anything.

Apr 24, 2015 at 12:37 PM | Registered CommenterBishop Hill

I really didn't understand that comment at all.

What is to misunderstand? Stevens released new estimates of a parameter used in Nic's peer reviewed article. Nic updated the work to incorporate Stevens' work.

What's the problem?

It might have been helpful if Stevens, who seemed so anxious to put out a personal statement to the world that "his paper does mean we ain't gonna fry", had instead told the Alarmist chatterati to STFU.

Apr 24, 2015 at 1:00 PM | Unregistered CommenterGeckko

Stevens will have to be careful he doesn't get thrown under the bus.

Can Climate activism get any more post-modern? He's denying what the Scientific American says he is saying.
The journalists at Scientific American have spoken. His research says 'X' (even if the scientist himself says it doesn't).

Apr 24, 2015 at 1:05 PM | Unregistered CommenterStuck-Record

Climate Scientist's sensitivity, goes up, the longer nothing happens as they predicted.

Apr 24, 2015 at 1:43 PM | Unregistered Commentergolf charlie

Lewis writes, at one point above:

"Since the climate system takes many centuries to equilibrate..."

Translation: None of us know--and really don't believe we CAN know, for "many centuries" yet--what we are talking about with regard to the "climate system", and particularly with regard to man-made climate change due to our fossil fuel use.

What I have discovered, with my 2010 Venus/Earth temperature-versus-pressure comparison, is:

The Standard Atmosphere model--and especially, the physics behind it, which assures a stable vertical temperature gradient--rules (as the real, global average, or mid-latitudinal, state) over all other processes and conditions in the atmosphere (being precisely confirmed by the Venus/Earth comparison).

The troposphere is fundamentally warmed, and the stable Standard Atmosphere structure maintained, only by direct absorption of incident solar radiation, not at all (beyond transient and local effects--known as "weather") from the planet's surface.

The CO2 climate sensitivity due to absorption by atmospheric CO2 of long-wavelength radiation from the surface is precisely zero, because that energy is simply "falling down" the globally(!) predominant vertical temperature gradient towards outer space.

Any CO2 climate sensitivity due to absorption by atmospheric CO2 of incident long-wavelength radiation from the Sun is also zero, because that energy merely goes to MAINTAIN the globally predominant vertical temperature gradient.

Today's climate scientists are chasing local (even quantum-mechanical) causes and effects, and know nothing of what I would call the overall design of the atmosphere--which I say again, is stable against all of the supposed causes and effects being considered by today's (clearly mis-educated) academics.

Of course, this is all beside the point, of the political, tyrannous war being waged against us all now.

Apr 24, 2015 at 2:29 PM | Unregistered CommenterHarry Dale Huffman

Harry Dale Huffman, climate science has no need to resort to technical wizardry like quantum mechanics etc, when politics and fearmongering have served it so well.

Science just confuses climate scientists, especially when their salaries are linked to funding.

Apr 24, 2015 at 3:12 PM | Unregistered Commentergolf charlie

Nic gets mentioned in SA? Really? Hell, even 3 months ago a sceptics name would have never darkened that illustrious journal's pages!

I think I hear ice skating in Hell.

Apr 24, 2015 at 4:19 PM | Unregistered CommenterDeNihilist

Were I gayathriv, I'd wonder whence the shiv.

Apr 24, 2015 at 7:57 PM | Unregistered Commenterkim

The problem is Sci Am trying to discredit Lewis. Steven's comfort level with Nic's work is not the issue. Using Steven's new aerosol estimate instead of the IPCC AR5 estimate further lowers and tightens the PDF for TCR and ECS. TCR Mode goes from 1.3 to 1.2; AR5 said 1.7-1.9. Lower sensitivity takes catastrophe out of CAGW and argues for adaptation rather than mitigation. That won't do for the Paris agenda.

Apr 24, 2015 at 8:05 PM | Unregistered CommenterRud Istvan

Stevens doesn't seem to believe that climate sensitivity is low.
But he doesn't seem to believe that we can make any assured statements on climate sensitivity just yet.

I think that climate sensitivity is low (the Pause leans me that way) but I can fully support his position. It's sound and rational - I just disagree with it for sound and rational reasons (to me anyway).

This is climate science being performed as science instead of trying to get journal editors sacked and reversing the null hypothesis.
This is good.

Apr 24, 2015 at 8:42 PM | Registered CommenterM Courtney

Yep, Rud, I was both cheered and worried by Bjorn's remark that the Ringberg uncertainties could be settled in a few years. I don't think he wants to upset the applecart before Paris. His problem is that the applecart is already upset. Segue to the Lady Killers.

Apr 24, 2015 at 9:12 PM | Unregistered Commenterkim

I don't think the climate cares about sensitive forcings in the AR5. It just carries on doing nothing significant. It is used to doing that.

Apr 24, 2015 at 10:26 PM | Unregistered Commentergolf charlie

Does anybody else feel that using ECS as an abbreviation in a piece about the relationship "equilibrium climate sensitivity" and "effective climate sensitivity" may lead to some confusion?

Apr 25, 2015 at 10:28 AM | Unregistered CommenterHenry

Henry wrote:

"Does anybody else feel that using ECS as an abbreviation in a piece about the relationship "equilibrium climate sensitivity" and "effective climate sensitivity" may lead to some confusion?"

Possibly, but I did define ECS as being the acronym for equilibrium climate sensitivity. It gets rather wordy if no acronyms are used.

Apr 25, 2015 at 10:51 AM | Unregistered CommenterNic Lewis

To update, Sci Am have issued a correction, removing the direct criticism of Nic's work but saying that the work was mis-interpreted by some of the media. Links on the Climate Audit post

To be honest, this is probably true, but it does smack of irony that a science journal has had to correct an article that should have been legitimately criticising some of the 'lay' media's over-interpretation of the science because they themselves have committed a similar (probably worse) over-interpretation. Oh, and added an ad hom or two into the mix...

Apr 29, 2015 at 7:33 AM | Unregistered CommenterIan Blanchard

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