Friday, October 10, 2014

Judith Curry's Sneaky Sentence

Judith Curry had an op-ed in yesterday's Wall Street Journal about her recent paper [PDF] with Nic Lewis -- it's paywalled, but the full text is on her blog.

It's titled, "The Global Warming Statistical Meltdown: Mounting evidence suggests that basic assumptions about climate change are mistaken: The numbers don’t add up." It begins
At the recent United Nations Climate Summit, Secretary-General Ban Ki-moon warned that “Without significant cuts in emissions by all countries, and in key sectors, the window of opportunity to stay within less than 2 degrees [of warming] will soon close forever.” Actually, this window of opportunity may remain open for quite some time. A growing body of evidence suggests that the climate is less sensitive to increases in carbon-dioxide emissions than policy makers generally assume—and that the need for reductions in such emissions is less urgent.
and concludes
This slower rate of warming—relative to climate model projections—means there is less urgency to phase out greenhouse gas emissions now, and more time to find ways to decarbonize the economy affordably. It also allows us the flexibility to revise our policies as further information becomes available.
which is, of course, exactly what the WSJ wants to hear.

As you probably know by now, that paper uses a simple model for temperature change and finds that
...median estimates are derived for ECS of 1.64 K and for TCR of 1.33 K. ECS 17–83% and 5–95% uncertainty ranges are 1.25–2.45 K and 1.05–4.05 K; the corresponding TCR ranges are 1.05–1.80 K and 0.90–2.50 K.
where ECS is the equilibrium climate sensitivity and TCR is the transient climate response.

The Lewis & Curry numbers are significantly lower than the IPCC 5AR's numbers (ECS: 1.5°C to 4.5°C, TCR: 1.0°C to 2.5°C), especially for ECS.

The paper has been criticized because it didn't use the latest data for ocean heat content, surface temperatures (Cowtan & Way), or aerosols. These are easily understood points that seem difficult to dispute. Hence, on RealClimate, Nic Lewis flatly refused to address these issues:
I will not waste time arguing in this venue about the validity and/or relevance, or lack of it, of Shindell (2014), Cowtan and Way (2013) or the Allen and Stocker TCR/TCRE relationship.
On Twitter Gavin Schmidt said a preliminary calculate of ECS using Lewis and Curry's method but with the most recent ocean heat data (Durack et al) raises their ECS upper limit to 6.1 C -- much higher than the 5AR upper limit (which also did not use data that came out after the 5AR cutoff date of 5/15/13, so the upper limit will likely increase). (Added 10/10: a commenter says this has been revised to 4.7 C.)

But, in her WSJ op-ed, Judith Curry wrote:
Using an observation-based energy-balance approach, our calculations used the same data for the effects on the Earth’s energy balance of changes in greenhouse gases, aerosols and other drivers of climate change given by the IPCC’s latest report.
This is sneaky. It's technically true, and makes her paper look like something on equivalent grounds as the IPCC, and something the IPCC missed. But it fails to mention that the Lewis & Curry method doesn't use the most recent data available. It doesn't even acknowledge that they exist, which is at least worth a caveat in the article. Without that, it misleads the reader.

Judith Curry is fond of criticizing others on ethical grounds. I wonder what she would say about the ethics of an IPCC-ish scientist who wrote an article without using the best and most recent data available -- and who even ignored its existence.

I think we all know the answer to that.

---
PS: The Durack et al changes to ocean heat content (OHC) are indeed significant. Their study found a large addition to the 0-700 meter OHC numbers of (2.2 to 7.1) x 1022 J/35 years. This works out to an average of 20 to 64 terawatts. The existing NOAA OHC numbers for the 35-year change for the 0-700 m region gives 140 TW. So the Durack addition is another 14-46%. That's why their abstract ends with "These adjustments...have important implications for sea level, the planetary energy budget and climate sensitivity assessments." (Emphasis mine.)

6 comments:

KarSteN said...

Thanks David! (Almost) Spot on!

First off, let us just put Gavin's revised ECS range as this information is readily available (looks a bit awkward, if you blame others for not having used the most recent numbers ;-)). The upper ECS limit would be as high as 4.7 C (rather than 6.1 C).

Funny to see how Nic would avoid any discussion on mainstream blogs (while feeling perfectly at home at vitriolic places like BH, where he can essentially write whatever he wants without being criticized), only to let Judith (I assume happily) do the trumpeting of his work. Perfect share of the workload. And how is it that the oh so oppressed minority can freely voice their opinion on almost every occasion. One thing is for sure, I can totally understand why Judith ended her blog post with the following remark:

"I am very pleased to have had the opportunity to write this op-ed, and I am hugely thankful to Nic Lewis and others (unnamed) who helped me improve this."

How could I not be happy for her. And how couldn't we all thank Nic for his unselfish efforts to save the planet from utterly biased mainstream climate scientists (who happen to have learned at lot more about physics than him, but then, why such nitty-gritty ... physics, paaahhh!!!).

John said...

The term for a non-ethical panderer who insists that others must be ethical: "flexible," one of the more pernicious terms in "the economy precedes life" school of "thought."

Any rebuttal yet submitted to Murderdoch's flexible fantasy sheet?

John Puma

WHT said...

I really don't think Curry is a credible scientist. She is the one that uses physics theories indiscriminately -- for example applying Bose-Einstein statistics to cloud droplet formation. This was actually included in her textbook on clouds released this year.

David Appell said...

Bose-Einstein statistics... That's great; I'll have to look that up. Thanks.

WHT said...

David,
There was a big discussion on her blog about the Bose-Einstein stats issue.

The issue with the Curry acolytes is that they will do anything to support her POV.

David Appell said...

Thanks WHT, I'll find that.

Anymore, mutual boosterism seems to be the primary purpose of many contrarian blogs.