How to Misinterpret Climate Change Research

[IanC]

a Scientific American article with the secondary headline-

Research into the cooling impact of aerosols sends climate contrarians into a tailspin

full article here- How to Misinterpret Climate Change Research - Scientific American

I encourage everyone to read it, and parse it for information that supports the headline. if anything it buttresses the 'contrarian' case.

Stevens narrowed the range in his study, cutting the cooling effect to about half of IPCC's suggestion of 1.9 Wm2...It's a tiny tweak with grand implications. If the maximum cooling ability of aerosols is only 1.0 Wm2, as Stevens suggests, the particles would offset only a third of warming caused by greenhouse gases. In comparison, at the IPCC's maximum cooling value, aerosols would offset two-thirds of the warming.

The misinterpretation of Stevens' paper began with Nic Lewis, an independent climate scientist. In a blog post for Climate Audit, a prominent climate skeptic blog, he used Stevens' study to suggest that as CO2 levels double in the atmosphere, global temperatures would rise by only 1.2 to 1.8 degrees Celsius. The measure is called "climate sensitivity."....That's less than the assumed 2 C threshold for catastrophic climatic change in parts of the world. It's also lower than an IPCC estimate that a doubling of CO2 will raise global temperatures by 1.5 to 4.5 C.

When scientists use temperature records from the 20th century to constrain sensitivity, they get low values. When they use records stretching many millenia, painstakingly assembled from trees and other proxies that contain imprints of past climates, they get values toward the higher end of the IPCC range of 1.5 to 4.5 C.

I get it that Stevens doesnt want to say that his work has added another coupla slashes to the 'Death of a Thousand Cuts' that is happening to CAGW and the IPCC. probably for political reasons as well as scientific uncertainty. but what does Stevens think about that evil denier Nic Lewis?

“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”

part of the message Stevens was responding to (read more at - Bishop Hill blog - Lewis on the SciAm article )

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”.

Scientific American is shrunken, twisted shadow of its former self.

ps. I hope everyone caught the reference to low climate sensitivity when using real(ish) temperature data, and high climate sensitivity using proxy estimates of temperature.

 

[cnm]

I must be misinterpreting it.

 

[Old Rocks]

In other words, Ian, them thar pointy headed liberal scientists don't know shit.

 

[IanC]

In other words, Ian, them thar pointy headed liberal scientists don't know shit.

is that supposed to make sense some how?

I linked to an article in SciAm that declares in its title that research has been misinterpreted. the actual evidence presented backs up the scientist being smeared as misinterpreting. and then I quote the author of the work supposedly being misinterpreted stating that Lewis didnt misinterpret him.

where do the pointy headed libruls come in? what are their names? the authors of the false SciAm article?

 

[Crick]

The point of the article and Stevens' press release is that his work indicates that, as he put it, the upper end of climate sensitivity is a little less likely. His work does not give global warming "a helluva beating" as Fox and Lewis would have it.

 

[IanC]

Steven's work implies that aerosols counter only 1/3 of CO2's warming rather than 2/3's. I think that is a significant slap to the model's climate sensitivity numbers. Don't you?

 

[Crick]

As he said, it makes the upper end less likely. I take it you also noted that sensitivity calculations from recent data tend towards the lower end of the IPCC's current range while the upper end results primarily from paleoclimatic data.

While we're chatting here, what lie do you believe I've told?

 

[IanC]

As he said, it makes the upper end less likely. I take it you also noted that sensitivity calculations from recent data tend towards the lower end of the IPCC's current range while the upper end results primarily from paleoclimatic data.

While we're chatting here, what lie do you believe I've told?

and as I've shown you before climate model calculated CSs are higher than those methods that calculate CS from actual data.

climate sensitivity for 2xCO2 is plummeting. IPCC knew that in AR5 and that is why they refused to give a best estimate. we have been through this all before.

 

[Crick]

They reduced the range. When you say "that is why they refused to give a best estimate", you're talking through your hat.

 

[Billy_Bob]

They reduced the range. When you say "that is why they refused to give a best estimate", you're talking through your hat.

The IPCC refused to give any estimate because all of their prior predictions were to high. And they were taking massive heat for the failure. Now they abandon their models and tell us its their best guess.... And then we see empirical evidence showing us a ZERO forcing or a negative forcing over the last 26 years.

 

[mamooth]

Once Ian used the term "CAGW", it was impossible not to laugh out loud at him. Only the most fervent WUWT cultists ware willing to publicly admit their cult affiliation by using that term.

 

[IanC]

Someone once said the most important quality of the modern liberal was to be able to hold two mutually exclusive ideas in their mind at the same time. I believe Steven's paper is an example of this. Measured aerosols are lower and more constrained than the amounts used in climate models therefore much less of CO2's warming is offset. But somehow it is being argued that this makes no difference and that high climate sensitivity calculated from the climate models is still realistic and predictions of <2C warming accurate. One or the other is wrong. Disagree with Stevens or disagree with the models because they cannot both be right.

BTW I am a liberal, but in the classical definition. I entertain many progressive ideals but not at the expense of reality.

 

[IanC]

The original source of this article has changed both the title and some of the wording. As far as I know SciAm is still running the original article and so has left in the mistakes.

 

[IanC]

Bump for Orogenicman