Monday, 21 January 2013

False Light

There's been an internet spat between Anthony Watts, operator of "The world's most viewed site on global warming and climate change", and Greg Laden, operator of the world's most viewed site written by Greg Laden.

Deviating from his usual subject of disbelief in anthropogenic global warming, Watts posted an item about a paper reporting signs of extraterrestrial life in a meteorite.  Unfortunately for Watts, the paper appears to be completely wrong, so when Laden read the post he wrote one of his own, mocking Watts, for not being "equipped to recognize this bogus science as bogus".  Watts, fired back a post accusing Laden of being a liar, on the grounds that Laden's screenshot of Watts' post cut off the second line, which qualified Watts' enthusiasm.  Laden was unimpressed.  Watts posted again, asking his readers whether he should launch a "false light" legal claim against Laden.  Laden laughed.

I've got nothing to add about the identification of alleged extraterrestrial diatoms, but I'm interested in the notion that the law in some US states allows bloggers to sue each other over what they've written, especially in view of the way US law has been influenced by the First Amendment.  I Am Not a Lawyer, but I can follow hyperlinks, so I followed the link Watts helpfully provides to a site discussing the "false light" law in Washington DC, where Watts proposes to sue.

The first, unsurprising point is that a false light claim requires "a false statement, representation, or imputation about the plaintiff".  There doesn't seem to be any false statement in Laden's article.  Laden has a screen shot of Watts starting his post with "This looks to be a huge story, the first evidence of extraterrestrial life, if it holds up", which of course is exactly what Watts did write.  It was a bit rude of Laden to cut off his screenshot before Watts' further qualification that "extraordinary claims require extraordinary evidence", but that qualification is irrelevant to Laden's point, which is that the paper Watts cited doesn't constitute so much as ordinary evidence.  The screenshot is not a false representation of what Watts wrote.  Laden goes on to say that Watts "was not equipped to recognize this bogus science as bogus", but Watts in his follow up does not disagree, writing "I've never claimed to be an expert in meteors or diatoms".

The second point is that "false light" is a privacy tort.  It's not intended to protect a person in the act of publicizing his views.  I don't see that one can claim to operate a "most viewed site" and claim privacy protection for what one writes on it.

The third point is that, in so far as the plaintiff is a public figure, he has to prove "actual malice", which words carry a special legal meaning that the statement complained of was published knowing it was false or reckless about its truth.  Whereas Laden seems to believe strongly in what he wrote.  Is Watts claiming not to be a public figure when blogging?

The fourth point is that there are strong first amendment protections for expressions of opinion and fair comment.  And Laden was expressing a critical opinion of Watts' writing.

So, to this lay reader, any legal action by Watts would seem to be beyond hopeless.

Introducing his threat of legal action, Watts wrote "I spent yesterday conferring with lawyers about the smear that Greg Laden made against me", but he doesn't actually say what advice the lawyers gave him, resorting instead to the formula "it seems that Laden’s actions in his original and follow up story meet the legal tests for "false light".

I predict that Watts will not sue.

Wednesday, 2 January 2013

More about Fears of Climate Change

In my previous post, I looked at a recent estimate by Lewis of climate sensitivity to CO2 doubling, pointing out that Lewis, while not explicitly disagreeing with SOD's data, used his own substantially lower estimate for heat uptake.

On the other hand, Lewis does explain at some length why he prefers a lower number to the IPCC's median estimate of -0.9 W m-2 for (non-volcanic, mainly sulphate) aerosol forcing - what the IPCC calls Adjusted Forcing from Combined Aerosol-Radiation and Aerosol-Cloud Interactions, or AFari+aci for short.  He points out that that estimate is "not what the observations indicate: it is a composite of observational, GCM-simulation/aerosol model derived, and inverse estimates."  He wants to use observational data only, so he takes the figure of -0.73 W m-2  from section 7.5.3 of SOD, and corrects SOD's estimate of total forcing for the difference.  Paul S, commenting here, says that that value wrongly treats estimates in some source papers of the indirect effect only as the whole forcing - the principal aerosol forcing mechanisms are the direct interaction with radiation, and the first indirect effect, which is caused by a change in cloud albedo resulting from droplet nucleation.

I've looked up the five papers listed on page 7-109 as sources for the estimate.  I present a crude summary of their results:
Quaas 2006-0.53Using LMDZ General Circulation Model
Quaas 2006-0.29Using ECHAM4 General Circulation Model
Quaas 2009-0.4-0.7-1.2See paper for why it doesn't add up
Sekiguchi-0.4-0.9-1.3Not including cloud fraction change

To get more confidence in the numbers, I've had a look at the difference between Adjusted Forcing and Radiative Forcing.  SOD estimates a centre value for RFari of -0.4 W m-2, and explains (page 7-45)
AFari adds the radiative effects from rapid adjustments onto RFari...Rapid adjustments are principally caused by cloud changes...Overall a best estimate for the rapid adjustment is taken to be –0.1 W m-2...[giving] an assessment for AFari of –0.5 W m-2
So its estimate of the direct effect is consistent with the numbers in my table.

SOD's preferred method for evaluating AFaci is to back it out from AFari+aci:
We produce a best estimate ... for AFari+aci in the following way. The global CMIP5 models and inverse estimates are grouped together and a bootstrapping method is used to estimate a mean ... of –0.98 W m-2. Processing the satellite-based estimates in the same way leads to a mean ... of –0.73 W m-2... We combine these two estimates into a best estimate ... for RFari+aci of –0.9 W m-2...
The AFaci is estimated as the residual between AFari+aci and AFari. We further assume that AFari and AFaci are additive ..., which yields to our assessment of AFaci of –0.4 W m-2. Models indicate that RFaci is less than AFaci, which implies an estimate of –0.3 W m-2...
[I think the "RFari+aci" there is a typo for "AFari+aci"]

Comparing the numbers in my table with the scatter plot in SOD Figure 7.10 on page 7-130, which shows seven points with the largest at about -1.0, it's apparent that the SAT points plotted are for indirect forcing only.  The two values in Quaas 2006 seem to have been plotted separately.  I can't see where the seventh point comes from.  Averaging the six points I've got gives -0.6, and adding a direct effect of -0.5 onto that gives a total adjusted forcing of -1.1 W m-2.  Whence the big difference from SOD's combined estimate of –0.73 W m-2?   It's hard to be sure, but it looks very much as if SOD has used the satellite estimates for indirect forcing only as if they're the whole forcing effect.  Three of the papers explicitly disagree with that, because they talk about additionally about the direct effect and a total effect.  The other two papers are clear that they're discussing indirect effects only.  If the combined effect is really –0.73 W m-2 and the estimate quoted above of -0.5 W m-2 for the direct effect is good, that implies an indirect effect of only -0.23 W m-2, lower than the estimates in any of the studies referenced.  This seems obviously wrong.

I've also looked up the seven papers listed as sources for the estimate of RFari+aci (two of them the same as above)

Dufresne-0.5-0.22-0.72Change in sulphate aerosols 1860 to 1995
Quaas and Boucher-0.35-Average of results for MODIS and POLDER satellite data
Quaas 2008-0.9-0.2-1.1
Quaas 2009-0.4-0.7-1.2See paper for why it doesn't add up
Storelvmo-0.94Mode of four values

Here simply summing the average direct (-0.58) and indirect (-0.46) forcings gives a total forcing of -1.04 W m-2. (I think the Dufresne result should be corrected for this purpose by adding in the 1860 forcing, but I've not done that.)

So the sources SOD references suggest an RFari+aci of about -1.0 W m-2 and an AFari+aci of about -1.1 W m-2.

In conclusion, SOD mentions the value of -0.73 W m-2 only in passing, and does not offer it as an estimate. And the source papers it refers to seem not to justify using it.  Lewis might reasonably have take SOD's explicit estimate for AFari+aci of -0.9 W m-2, or he could have gone to the sources using his preferred method and come up with a consensus value of -1.1 W m-2.  I think he is not justified in using -0.73 W m-2.

Using a value of -0.9 together with my previous heat uptake estimate increases the median sensitivity to 1.95.  Using -1.1 increases median sensitivity to 2.29 .


It's very possible that this post could be improved by expert interpretation of the source materials.  I welcome suggestions and corrections, and may undertake extensive revision in their light.

[I've omitted throughout estimates and discussion of uncertainties.  Which is not to say that they're unimportant, but I'm concentrating here on the headline numbers.]