More mad Japanese gadgetry

On the BBC news website via Chris Randles, we find this microwaveable bra and knicker set:



Chris invites me to deride their uselessness vis-a-vis global warming. Sorry, but if our "OLs" (office ladies) wish to walk around in skimpy clothes all winter, I'm not going to object too strongly. And you thought I was here for the higher salary and status, great working conditions, strong infrastructure, academic freedom, lovely climate and fabulous countryside?

More underwear fun can be found here.

Bill Gray won't bet on cooling

As you may recall, a couple of months ago Bill Gray appeared in front of the US Senate Committee on Environment and Public Works to testify on his area of expertise, hurricane prediction. Unfortunately he didn't restrict himself to things he knew about. Much of his testimony focussed on the obviously bogus line of argument:

How can we trust climate forecasts 50 and 100 years into the future (that can’t be verified in our lifetime) when they are not able to make shorter seasonal or yearly forecasts that could be verified?

This is standard septic drivel that is easily disposed of (and if you want more technical details, my own work demonstrates some ideas about how to do it in practice). Note: this does not in itself prove that the models are right, it merely illustrates why Gray's line of reasoning is garbage. But anyway, this isn't really my main point. You won't find it in his written statement, but in the video of the proceedings, he clearly says:

I predict, now I think I know as much as anybody, I'll take on any scientist in this field to talk about this, I predict in the next 5 or 8 years or so the globe is going to begin to cool as it did in the middle 40's.

I emailed him some time asking if he will back up this statement with a bet. William Connolley and Brian Schmidt at least have done the same. None of us (to my knowledge) has had the courtesy of a reply. Given his statement above, I do not believe it is too much to expect that he should at least quantify his prediction in terms of his confidence (what odds he would place on his prediction being provved correct). To not do so seems to be clearly misleading the Senate Committee hearing.

I guess I shouldn't be surprised that something which is so obviously a circus has a few clowns present...

Culture Day

Following on from the silly gadget of yesterday, today was the national holiday of "Culture Day". Living in Kamakura, most of the culture is of the ancient Buddhist variety (Kamakura was Japan's capital in the Kamakura Era [1185-1333], and a huge number of temples were built around that time). So we wandered over the hill to Kenchoji, which has its annual "airing of the treasures" on this day. We've seen it before so just had a quick look at this friendly dragon painted on the ceiling of one of the halls (whose eyes seem to follow you round the room) and then headed into town.

November - February is oyster season in Japan, so we had some, fried, for lunch. They don't seem to be eaten raw here much, which is odd considering what else does! There's my plate of deep-fried oysters and assorted side-dishes, all to be washed down with a cold beer. Oishiiii!

Walking home takes us through the grounds of Hachimanguu, Kamakura's main shrine. The "7-5-3" festival is going on around now. At this time of year, boys (5 yo) and girls (7,3 yo) get dressed up in kimonos, taken to shrines by their proud parents, and wished luck by the priest for the coming year. All for a suitable fee, of course. The more you pay, the better your luck.

Update
I've just heard that one of our senior members of staff was yesterday presented with "The Orders of the Sacred Treasure" for services to the nation and public (Dr Ninomiya is a former Director-General of the Japan Meterological Agency). This award is one of the 5 Orders of Culture handed out annually on this day. I will resist the temptation to add any comments about him being brought out for public viewing once a year :-)

Only in Japan...

...originator of almost all of the world's silliest gadgets, would you find:



a taxi with a wind-powered mobile phone charger mounted on its roof. Ok, maybe I'm being a bit unfair to Japan. I should also mention that many of the world's coolest gadgets are invented here too (this one is relatively mundane, although still very cool). But putting a wind turbine on a car roof certainly crosses the line between normal and wacky.

It is justified here as a purely promotional exercise to encourage the use of greener energy, which I suppose is fair enough. Some other web coverage seemed to believe that it was a genuine (though small) contribution to reducing carbon emissions, which is a bit worrying. Putting a fan on the roof, thereby increasing drag, just so a small proporrtion of the extra fuel burnt could be converted into electricity, is a bizarre approach to energy efficiency!

New paper

Those who keep a close eye on my work page (yeah, right) will have noticed a new preprint appeared there recently: Efficiently constraining climate sensitivity with paleoclimate simulations. SOLA Vol 1 pages 181-184 2005. It's only a short 4-page summary in a rapid response journal (just right for sneaking inside the IPCC deadlines) but breaks new ground in 3 ways which I hope will help to point the way forward for climate prediction.

• We use an efficient multivariate parameter estimation method with a state-of-the-art GCM for the first time. This is many many orders of magnitude more efficient than multifactorial sampling, and several people have told us over the last couple of years that it couldn't be done. (I won't deny it has some potential drawbacks, though - but we haven't found any show-stoppers).
• We have tried to take some account of model inadequacy - by which I mean the fact that there are no "correct" parameters for which the model actually looks just like the real world, so the standard "perfect model assumption" is wrong.
• We have used out-of-sample data (in this example, a simulation of the Last Glacial Maximum) to attempt to improve the rigour with which predictive skill is assessed. Merely managing to fit a set of data doesn't automatically mean that the model will skillfully predict climate under a different forcing!
  

All of these 3 aspects are approached in a rather simplistic manner, and all can (and no doubt will) be improved, eventually by us if no-one else does it first. But it's good to have a benchmark, if only a rather low one, to shoot for in subsequent work.

Oh, by the way, we didn't really learn anything startling about climate sensitivity. But we all know that's about 3C anyway :-)

The Blue Planet Prize

Every year, the Asahi Glass Foundation awards "The Blue Planet Prize" to two individuals or organizations "who have made major contributions to solving global environmental problems". The winners are invited to Tokyo where they give public lectures on their work, and we usually go along to listen (and perhaps do a bit of shopping in the Big Smoke).

One winner is usually a top-notch scientist in the traditional mold (past winners include Wally Broeker, Suki Manabe, Robert May) and the other more of an activist or politician (Vo Quy, Gro Harlem Brundtland, various worthy organisations I may have vaguely heard of). This year, Nick Shackleton and Gordon Hisashi Sato were the joint winners. They talked at some length about their work, which was very interesting, but then both ended with rather incongruous calls to cut CO₂ emissions. The sentiment may be well-meaning but it all seemed a bit odd.

However, their comments were nowhere near as odd as the introductory film we were shown for the first time this year, which consisted of pictures of war, devastation, pestilence and natural beauty all overlaid with an inane voice-over asking cheesy things like "Why are we killing Mother Earth". It would have been rude to laugh out loud, but I couldn't suppress the odd snigger.

I hope they received enough negative feedback that next time they'll revert to just having the talks!

The Guardian on prediction markets

A short article in the Grauniad a couple of days ago concerning prediction markets:

Markets have now been shown to out-perform collections of "experts" in predicting monthly economic data better than the best economists, or in accurately forecasting whether WMD would be found in Iraq. Mathematicians believe that the existence of a market allows large numbers of people effectively to "pool" their collective wisdom, with each new trader able to bring a unique new insight into the mix.

How can this power be harnessed for the social good? Iowa has recently been experimenting with the trading of "flu predictions", in which traders have been asked to forecast the state of flu alert that will be in place in the state several weeks in advance. Researchers have found that the flu prediction market has been able to predict the state of flu alert with 90% accuracy a fortnight ahead of time - long enough to allow medical staff to gear up prevention and treatment regimes. Iowa economists will next turn their attention to a market that will predict the number of bird flu cases in the US. It cannot come soon enough.

Shadowing and chaos

Following on from previous posts on chaos, I'm now going to look at a bit of theory in more detail, in particular the shadowing lemma.

The issue the shadowing lemma addresses is this: given a set of differential equations which describe a chaotic system (such as the Lorenz equations), we have no way of calculating a true trajectory, since all of our numerical methods make various approximations (such as using the finite difference (x(t+Dt)-x(t))/Dt in place of the true derivative dx/dt, for example). Moreover, digital computers only calculate and store results to finite precision, so there are rounding errors at every step. In a chaotic system, these errors will grow exponentially and so the model's trajectory (when initialised from a particular state) will differ wildly from the exact system. So what can we hope to learn from the model?

The shadowing lemma provides a very encouraging answer to this problem. It assures us that, although the true system does not track the model's output when they are initialised from the same starting point, there is a trajectory of the true system (starting from a slightly perturbed initial state) that stays close to the model for an arbitrary length of time. So the model output does in fact "look like" a trajectory of the system after all. The pdf file linked from here is one of the most accessible descriptions I've found on the web (the "hyperbolic system" it refers to is a technical term which includes the standard chaotic systems of classical physics).

Stoat has a nice set of graphs showing the growth of small perturbations in the HADAM3 model (atmosphere component of the HADCM3 atmosphere-ocean GCM). As I mentioned in the comments to his post, I am a little suspicious that a small local perturbation can kick off differences across the whole globe within a day or so. Note that the "model physics" does not support pressure (sound) waves so information should only propagate at around the speed of the flow. It seems likely that the propagation speed in these experiments is instead a numerically-determined rate of one grid box per time step. Fortunately, the shadowing lemma comes to the rescue here. Although the perturbation he used would probably not grow in this way given a numerically precise solution to the fundamental equations, the shadowing lemma tells us that there is a true trajectory of the exact system which looks similar to each model run, and therefore their two sets of initial conditions form a (control,perturbed) pair whose difference really does grow as the plots show. Their initial difference would necessarily be small in magnitude, but I expect it would be globally dispersed in nature.

Now, Professor Eykholt made repeated reference to the shadowing lemma in his emails to me, which you can read on Roger Pielke's blog. (I'm amused to note that they're both happy to publish my email without bothering to ask, which rather puts Eykholt's "totally unethical" accusation into context). I struggled to find a way of interpreting his first comments so as to be somewhat relevant, and I can see now how I misunderstood them as a result. However, given that the shadowing lemma only applies to chaotic systems in the first place, it seems bizarre to attempt to use it to demonstrate that a system is not chaotic. In fact, on re-reading his emails his line of argument appears very strange indeed. It is precisely the shadowing lemma that tells us that there are initially-close trajectories of the real system which diverge in the way that the numerical trajectories do, as per the discussion of HADAM3 above. I cannot see how his statement "The shadowing lemma gives you a scale beyond which small perturbations cease to have any important effects" can be reconciled with what is generally understood about chaotic systems. Unfortunately, he refuses to communicate any further on the matter, so I'll never get to the bottom of what he is thinking.

Still flapping

As an update to my previous post, Prof Eykholt has emailed to say that I have misrepresented him. However, although of course I apologise for any embarassment caused, it is not actually clear to me how I actually misinterpreted his email to me. Some of his original comments seemed a bit unclear to me, but I thought I had managed to interpret them in a way which was consistent with what I understood of chaos theory (I did email him back to check, but he didn't reply to that). I find it hard to believe that he really means to support Roger Pielke's position that small pertubations will vanish completely in a chaotic system. After all, Prof Eykholt is also quoted as saying (on Roger's blog):

The butterfly effect refers to the exponential growth of any small perturbation.

So I am now more puzzled than ever as to what he really means. I've asked him and Roger if they can supply any theoretical or practical support for Roger's claim that below a certain size, small pertubations fail to affect chaotic systems (at least, the atmosphere in particular)...

Update

Ok, on re-reading Prof Eykholt's emails, I can now see how I misinterpreted them, and I'm sorry for any confusion I have caused. In my defence, I did email him back to check that I had understood his point correctly (he explicitly invited me to do so) last Thursday, and never received a reply. I still think that my comments on chaos are entirely uncontroversial and in line with the overwhelming maority of the field. Prof Eykholt's emails to me lean heavily on the Shadowing Lemma, so I'll probably do a post about this shortly, explaining its relevance (or otherwise) to the debate.

More on the butterfly flap

(See here for previous.) Well, RP Snr's promised followup post consisted of an odd quotation from Richard Eykholt who works in the physics department of Colorado State University. His quotation contains the comment that

"The point of the [exponential growth of minuscule perturbations] effect is that it prevents us from making very detailed predictions at very small scales, but it does not have a significant effect at larger scales."

which RPSnr takes as vindication of his claim that small perturbations do not affect the real world, only models.

The quotation seemed a bit unclear, and RPSnr's position is clearly wrong, so I emailed Prof Eykholt to see what he really meant. He explained that he was referring to issues of practical prediction, in which case any additional perturbation of a similar size to the rounding error of a finite precision computer model cannot harm predictability over broad spatial scales, since the model already has lots of perturbations of equal size (not to mention more substantial errors) which limit predictability. Of course this is true (to the point of triviality), but it hardly seems relevant to RPSnr's claims. Further, Prof Eykholt explicitly agreed that a small random perturbation in a chaotic system will grow to a point at which the original and unperturbed systems are completely decorrelated.

Meanwhile, back in the comments section of his post, RPSnr seems so determined to defend his untenable position that he is now claiming that not only turbulent energy but even momentum itself will dissipate in the real world...