The biggest control knob: Carbon dioxide in earth’s climate history

[BPSDB] By Richard B Alley of Penn State University.

This was the keynote lecture at the American Geophysical Union meeting (a vast conspiracy of scientists to find out all they can about how the Earth works) last year.

It’s a good summary of what we know about the role of CO2 in the Earth’s climate, a proof that climate scientists really do take into account all the climate changes that have happened over the Earth’s history, and why that knowledge is still bad news for us as we belch huge amounts of buried carbon into the atmosphere.

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Countering disinformation on climate

[BPSDB] In the wake of the latest outrageously dishonest headlines misquoting Phil Jones, the excellent  Open Mind blog presented a good account of the error, and also initiated a civilised and productive discussion on how to present the facts to the general public. I urge you to read it. I hope to post some thoughts of my own on this in the near future.

Why should I make the data available to you

[BPSDB] In many comments on the CRU hack I’ve seen it alleged that Professor Phil Jones of the University of East Anglia Climate Research Unit denied his data to another researcher with the words, “Why should I make the data available to you, when your aim is to try and find something wrong with it?”

Whenever I’ve seen it quoted, it’s implied that  Jones made the comment in one of the emails. I finally got around to looking for it, in the file I downloaded soon after the hack was made public – and it ain’t there. Not perhaps surprising, as it really doesn’t sound like the sort of thing an academic would say, except jokingly or sarcastically.

Indeed, the words are there. In August 2007, a fellow researcher warns Jones that the words are being attributed to him by someone else. In October 2009, another colleague sends Jones a copy of the text of an article in the National Review of 23 September 2009. In this Patrick Michaels quotes Warwick Hughes as alleging that Phil Jones said, “We have 25 years or so invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it?”.

So it doesn’t appear to be evidence that Jones actually wrote it.  Given the unreliability and political commitment of all the links in this chain, and that this was one of the main pieces of evidence for the supposed ‘conspiracy’, I think there is even less evidence of wrong-doing.

Conspiracy theories have a tendency to spawn new conspiracies: here’s a climate ‘sceptic’ who thinks the CRU staff may have leaked the emails themselves to make ‘sceptics’ look stupid. If so, they’ve succeeded.

Words: Correction, Compensation, Adjustment, Proxy, Trick

[BPSDB] Years ago, when I was a researcher, I used a technique called ‘infrared spectroscopy’ a lot.  It involves passing infrared radiation through a sample of a substance, then splitting the infrared radiation up into its various frequencies (a spectrum) and measuring which frequencies are absorbed by the substance. Most substances (though not all) absorb IR radiation.

The resulting pattern of peaks, called bands, can be used in analytical chemistry to identify compounds, if their IR spectra are known. Under favourable conditions, such as the vapours at low pressure I often worked with, you can get information that will help (along with other techniques) to discover the actual shapes of the molecules, and even to discover facts about the internal electronic structure.

So, in theory, all you do is pass the IR through the sample and record the spectrum, right? No. Between the lamp and the sample are other things that absorb IR. These could include the solvent (if you’ve had to dissolve the sample), but, in particular, there is carbon dioxide, which is a component of air that strongly absorbs IR. So your spectrum includes bands from the interfering substances, which will complicate matters and likely obscure details of the spectrum you want to see.

But there is a clever trick (that word came immediately to my mind writing this, in the sense of a clever thing to do). That is, you split the IR beam into two, and pass one half through the sample and the other through a path of the same length containing all the things (air, solvent, etc.) except the sample itself. Then you can electronically subtract the signal from the reference beam (the one without sample) from the signal from the sample beam. And you are left with the signal that comes from the sample alone. Clever, eh?

This is called correction or compensation. There is nothing dishonest about it. The result is a genuine spectrum. If anyone is being cheated, it is nature being tricked into giving up her secrets, as without the compensation or correction you would have much less, if any, information about the sample spectrum.

I mention this, as hordes of global warming ‘sceptics’ have been crying ‘fraud’ simply through seeing words like ‘correction’, ‘adjustment’ and even ‘trick’ in some otherwise unremarkable stolen emails containing informal correspondence between climate scientists. These words do not in themselves imply anything nefarious. Now there may have been improper behaviour on the part of the scientists, but that would require some contexts for these words, providing some actual evidence. But no evidence for serious wrong-doing (apart, apparently, from getting irritated with ignorant harassment) has been presented.

Corrections are not limited to the lab. Whenever you press the ‘tare’ button on a set of kitchen scales, you are making a correction, by subtracting the weight of the bowl from the flour you are weighing out. Without that correction you will have a less satisfactory cake. Corrections, or compensations, or adjustments, are an essential part of the tricks needed to extract real data from the raw data of the real world.

In science, most things are not measurable directly. Temperature is one of them. When you measure a temperature, you are actually measuring an electric current that changes numbers on a display or moves a needle on a dial. Or you are measuring the expansion of a liquid (alcohol or mercury) along a tube. Neither method measures temperature directly, which is, in fact, impossible. What you are measuring is a proxy for temperature: another measurable quantity that is related to temperature in a way that is known from theory and tested by practice. But the manufacturer still has to make corrections to ensure that the fixed points of the measuring device correspond to the fixed points of the standard temperature scale. Building these corrections in is called calibration.

Actual measurements of temperature, using thermometers, go back only a short time, at most a couple of centuries in relatively few places. That means that scientists trying to study temperature way back in history or beyond have to use proxies – whatever they can find, wherever they can find them. The proxies include annual tree-ring growth, ratios of isotopes of oxygen in ancient snow, and the patterns of annual deposition in lakes (varves). These may not vary in a straight line relationship with temperature. Also, nature may inconsiderately have placed the proxies in different places at different times, such as trees growing at different heights.

To try to make these separate items match up, you need to calibrate, or adjust, the data, so they represent the temperatures correctly. For example, you may need to allow for trees growing at different rates at different heights. You can imagine that a great part of research is given over to debate about these corrections. But there is nothing essentially dishonest about doing this. If you find that numerous different proxies, when compared over the same period of time, agree pretty well, then you can have reasonable confidence that the proxies are measuring the same thing. So it is with the so-called ‘hockey-stick’ graphs.

Trick or heat, continued

[BPSDB] 32,500,000 hits for ‘climategate’ on Google today, and I’m beginning to feel as if I’ve seen most of them. Lots of repetition there, but what I have yet to see is any actual evidence of climate data being suppressed or distorted to falsify conclusions. Only tendentious interpretations of selected quotes from emails that were themselves selected from what must have been ongoing conversations.

Possibly the scientists involved did not behave entirely correctly to other people, but I expect that will come out in the investigation.  I’m both a sceptical person and an old-fashioned believer in innocent till proven guilty, so I will wait for the results of the investigation before passing judgement on the scientists.

A  thousand emails out of a something like a decade and a half means that the emails have been drastically selected out of a very much larger number (and possibly redacted too). Whoever stole the emails is clearly manipulating his audience and rather a lot of commenters seem unaware of the possibility that they are being manipulated.

What is also clear that some people jumped to ‘obvious’ – just too obvious – and daft conclusions about what certain emails ‘meant’. For example, an email by Kevin Trenberth was widely taken to be a climate scientist expressing private doubts that global warming is happening, but it was actually a comment on short-term variability and was discussed openly in his publication here. Lots of people desperate to believe that global warming is  a hoax fell for this one, like Andrew Orlowski at The Register and the frankly begging-to-be-taken-to-the-cleaners James Delingpole.

Spinning greenhouse gas numbers: good or bad?

[BPSDB] Spinning numbers in more ways than one. The explanation of the science is correct, and the purpose of the counter seems admirable. But of course, the supposed precision of the numbers is spurious.  (It grates on this former science lecturer, who used to have to explain why all the digits output on a calculator were just not significant.)

But, if the figure was displayed to a reasonable precision (maybe hundreds of millions of tons?), you just would not see the display updating. The whole point of the display is to convey how we are recklessly pumping carbon dioxide into the atmosphere, with consequences that can be calculated, but with further consequences that cannot be foreseen. In this case, spin actually conveys the message more vividly, through an appeal to feeling (seeing the numbers changing creates a sense of unease and restlessness) and an implicit call to action, rather than a logical appreciation of the figures and their scientific implications.

Cold weather freezes columnists’ brains

We’ve been having a colder winter this year in the UK than we’ve had for some years (about thirteen, or eighteen or twenty years, depending who you’re reading). Some people seem to think this is evidence that global warming has stopped, or even that the world is getting colder (see Melanie Phillips, Gerald Warner, Richard Littlejohn, Christopher Booker and a host of their blog hangers-on, ad nauseam).Surprisingly, that is, because these are the sort of people who like to claim they are talking ‘common sense’, yet they don’t even seem to be aware that when it’s winter here it’s summer in the southern hemisphere. So it’s not cold ‘all round the world’ when their own asses are freezing. As it happens, it has been reported that Australia (the southern part anyway) is currently having its worst heatwave on record.

Neither the UK’s winter nor the Australian summer are in themselves evidence for either heating or cooling. The key is in the two words ‘global’ and ‘average’, because the global average temperature is related to the balance of heat received from the sun and heat radiated back into space, which is what keeps much of our planet within a comfortable range of temperature for life. This is why careful measurements of temperatures around the world are much more significant than whether Gerald Warner’s feet are cold. Real Climate has discussion of the data up to the end of 2008.

None of this will stop any the above hacks from going on believing what they want to believe. But it’s not ‘common sense’ to claim at the same time that the climate is too complicated for computer models and also that 

because it’s icy outslde there is no global warming. [bpsdb]