Archive for June, 2010

Lying Liars Who Lie! Liar!

June 25, 2010

Accusations of dishonesty and charged language are thrown around quite lightly on the internet, in general. The web is the home of heated rhetoric. But here is something pretty bizarre: Roger Pielke Senior is attempting to engage RealClimate on a paper of his and colleagues. Eric Steig made this astounding statement:

[Response: Being listed on our blogroll does not constitute endorsement. In general, the sites we do list — whether they are run by scientists or not — tend to get the science right much of the time, and hence are consistent with our mission. Being not-listed could mean that a) we haven’t heard of the site, b) that it is uninteresting or unimportant, or c) that we consider it dishonest or disingenuous with respect to the science. Pielke Jr, Blackboard, and ClimateAudit all fall squarely into the latter category.–eric

Steve McIntyre, Roger Pielke Jr, and Lucia are all “dishonest or disingenuous with respect to the science? Really? I can see why they must maintain that of Steve McIntyre. I can even see them not caring for Lucia’s work, although I know of nothing that she has said or done that RC could reasonably claim was wrong. But Pielke Jr?  Dishonest/disingenuous with respect to the science? He accepts the “consensus” of the IPCC, but deigns to criticize some elements of climate policy and thinks that these folks could perhaps stand to behave a little better. So, that’s disingenuous? Um…I think such insanity speaks for itself.

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Model “Skill”

June 23, 2010

This presentation by David Stockwell comes highly recommended by me. He mentions something very interesting to those of us who like to test hypotheses like climate models: A metric for assessing the performance of a model compared to a benchmark, in this case the Mean. The statistical measure of skill is called Nash-Sutcliffe Efficiency, and it originates from Hydrological modeling of river discharge. The idea is that one wants to minimize the ratio of the sum of the squared errors of a model to the sum of the squared errors of simple average, and get as close to 1 as possible by making this ratio, which is subtracted from 1, close to zero. But the drought predictions climate models are, in the case of David’s example, Australia, worse than the long term mean. Interestingly, in Richard Lindzen’s Heartland presentation, he noted that one argument for models is that they are our “only tool”:

The notion that models are our only tool, even, if it were true, depends on models being objective and not arbitrarily adjusted. However, models are hardly our only tool.  Models do show why they get the results they get.  The reasons involve physical processes that can be independently assessed by both observations and basic theory.

But David shows that one could perhaps go beyond this. Not only are models not our only tool, they are, in some cases, actually worse than nothing. Why models produce incorrect results for drought trends in Australia is something we might be able to investigate and it might prove worthwhile. But for the purposes of telling us about the future, models which perform this poorly with respect to records that predate them, can only mislead us, and dangerously so.

I would also like to add a thought of my own: The NSE could be generalized to use any “model” as something to compare models with, rather than just an average. This might allow the possibility of asking whether models perform better than slightly more complex models than the average, such as linear trends. Of course, the Mean is a standard to test against, but there are interesting possibilities with regard to testing models performance against observations relative too each other. For one thing, it might be possible to see if models performance with respect to the observations has improved over time.

Jerry North, Go Back To Grade School

June 17, 2010

On June 4th of this year, Steve McIntyre informed us that Texas A&M professor Gerald North complained that Climate Audit dared to mention him in an unfavorable light:

Hi All,
I would appreciate your leaving me out of your blogs.
Jerry North

Steve’s response, in brief, was that:

If he wanted me to not mention him, a good starting point would be to stop saying stupid things. Unfortunately, since Climategate, he’s done exactly the opposite.

One would have hoped that he would have eventually learned his lesson. Well, nearly two weeks later, and he is now saying things which are even stupider. WUWT has a commentary on a story from A&M which is filled with nonsense. It is very disturbing, however, that a distinguished scientist like Dr North seems to think he can just make false statements about what is going on with the climate system-it’s either that or he is ignorant, in which case he is making shit up. In particular, the claim that:

Texas temperatures are going up pretty much like the earth’s temperatures are…Last summer was a really hot summer, and while I say that is a fluctuation, it does probably indicate things that we might expect in the next 20 or 30 years.

From which the authors of the article clearly derive:

Global climate changes are having equal effect on Texas‘ climate, which is part of the reason for the increased temperatures over the summers.

The only problem is that Dr North’s claims are just wrong! According to NCDC, the trend in Texas annual average temperatures 1895-2009 is 0.00 degrees Fahrenheit per decade, and the change in summer temperatures is -0.02 per decade. And the “extraordinary” last summer? There have been thirteen warmer summers! That would mean that the “extraordinary” summer wouldn’t even be in the five percent probability or less required to reject the hypothesis that it is different from the “normal” summer! How is that “extraordinary”?

Sorry, Jerry, but you are either a liar or ignorant, and an ignorant person who speaks as if he has wisdom…well that’s at least as bad as a liar.

EDIT: I was actually waiting to see if anyone would criticize me for this post before adding this, but apparently my blog is less popular than I thought. You may have seen at WUWT that Dr North sent an email that claimed that the impression their article left was wrong. In some respect, there was a confusion arising from the original story, which was being dissected at WUWT-the interviewer who got North and Dessler’s statements did not differentiate between what North and Dessler were talking about (projections for the future/versus the observed record) I was not confused about this at any point and it is unrelated to the text of this post. While North believes that his “hate mail” is driven by confusion, and thinks that he was not in error per se, it is clear that, having selected the statements directly attributed to him, not the comments I knew were from Dessler or the errors I knew were the reporter’s (because I could tell from context in case you are wondering), I still find that North made statements which are either lies (deliberate falsehoods) or stupid (easily shown to be wrong statements that one would think a distinguished scientist could check before making). Note that in the quotes attributed directly to him he makes the claim that Texas is warming just as the rest of the Earth which can only be a reference to the observed record, as it is present tense. He makes the claim (and here there can be no ambiguity as to whether the interviewer somehow changed his tense, which I suppose you could argue for on the former point, this journalist didn’t seem to be very good anyway) that the summer of 2009 was extraodrinary. Given that it isn’t even in the top ten summers, North was ludicrously wrong on this point. I think I am giving the Dr’s character the benefit of the doubt in suggesting that he needs to learn some very basic things over again, like checking to make sure a claim you are making is really true before making it. If he feels like he is smarter than a 5th grader, he should let me know and I’ll change it to “go back to Sunday school and learn not to lie”.

How Does Climate Sensitivity Relate To Radiation Flux?

June 8, 2010

Let’s first remember that, as we previously talked about, Climate sensitivity corresponds to the amount of warming that will occur from a certain amount of “forcing”-change in the Earth’s radiative cooling that arises form something other than temperature changes themselves. In order for the Earth to maintain a constant temperature, the amount of radiation it receives from the sun must equal the amount that it reflects or re-emits back to space. Otherwise, because it is gaining or losing energy, it will warm or cool. Of course, warmer bodies emit more infrared radiation, so the Earth just needs to warm or cool enough to make the net radiation flux equal to zero again. The precise amount of temperature change necessary corresponds to the climate sensitivity. Of course, once again, there are caveats, which related to my previous post. But let’s forget those for a moment. Is it possible, in principle, to determine the climate sensitivity from looking at the Earth’s radiation budget and it’s response to temperature changes (feedback)? In fact, it is, in principle, possible, and one can even quantitatively describe how this can be done. However, keep in mind that it will only be possible to do so if the changes in the Earth’s radiation budget can be explicitly isolated as changes due to temperature, and changes due to other things, like CO2 (“forcing”).

This point is greatly emphasized by Roy Spencer, but our interest here is only in the Mathematics so this can be better described to people. I may not be the best person to do this, but it interests me and I’m going to try. The sensitivity of the climate relates to the theoretical response with no feedback as:

ΔT=ΔT0/(1-f)

Where delta T corresponds to the response with feedback, delta T naught to the zero feedback response, and f to the feedback factor. The feedback factor in turn depends on the radiation flux caused by temperature change (the total flux minus the forcing flux) as:

ΔF/K=-3.3(f)+3.3

Where ΔF/K is radiation flux per degree Kelvin, and 3.3 corresponds to the zero feedback flux per degree Kelvin, so for a feedback factor of 0, the ratio would be 3.3 W/m2 and if the feedback factor is one (corresponding to division by zero in our sensitivity formula), then no amount of change in K will create any change in ΔF, corresponding to infinite sensitivity. A feedback factor of -1, corresponding to half the zero feedback sensitivity, requires that the flux per Kelvin be double the no feedback value. Roy has been finding values of flux per Kelvin of ~6 W/m2, which corresponds to a feedback of ~-0.82, almost cutting the zero feedback sensitivity in half. The amount of temperature change to eliminate the flux from doubling CO2 (3.7 W/m2) would be a little over .6 degrees Kelvin, which is a very low sensitivity. Of course, determining the value of ΔF/K is difficult, as Spencer has himself pointed out. But the values found in climate models appear to be distinctly different from the observed fluxes.

Anyway, the main point of this post was to explain the math involved. I may revisit this later to investigate the feedbacks myself. It’s perhaps a topic for future investigation.

I would also like thank Roy for confirming my calculations.