Saturday, September 29, 2007

Last day of summer.

Yesterday (a single day of 26C within a week of otherwise plummeting temperatures. Down to 21C one day ... BRRRR!) may have been the last day of summer. To celebrate, I took the last summer holiday of the year, to Iceland, courtesy of Google Earth. First of all I visited Reykjavik, and admired its tininess compared to the sprawling 30 million people's worth of conurbation that I live in. The photos of views over the city look like a medium sized British town. Then I went for a fly over some of the glaciers and thought how sad if would be if they melted and we couldn't any more go flying over glaciers on a Friday afternoon. Or - could we lobby Google Earth to keep historic earths so when the whole earth is a big red desert we can see what the good old days were like?

It was at this point that I noticed that the continental shelves and the ocean ridges are visible on Google Earth. Of course I immediately thought of this and went prospecting. Well, probably a little knowledge is a dangerous thing, but it was fun to go and look without having to get in a Russian submarine. Seems to me that most of the Arctic is part of Greenland and Canada. The gap of deep water between Russia and the Arctic looks ominous to me - I think Putin's trying it on. More amazingly, we can all go and look and develop an opinion based on just enough evidence to reinforce our prejudices.

Anyway, as long as they don't have a big war over it, life looks pretty nice for those last few breeding pairs that will be left in Canada, Russia and Greenland. Plenty of oil, nice long summer evenings, and regular holidays on the balmy beaches of Iceland.


Thursday, September 27, 2007

Broken societies?

This diatribe is the result of some rather scary conversations I (jules) have been having with Japanese friends recently... James is off, "probably" in the UK, so .. hee hee I kidnapped the blog! You won't like it...

The most recent sound-bite that seems to be catching on on BBC Radio Five is the "broken society". Most recent I heard about was the Arch.Bish. of Canterbury. Apart from the sound-bite I found a report in the Guardian. Of course faith is not actually mentioned, but what it seems to boil down to is that the Christian tenets of an un-broken society, namely faith, hope and love, have, in the UK, been exchanged for reality TV, celebrity and gang warfare.

Now the Japanese society is not broken. It is just as it should be, as it is meant to be. Tiny kiddies walk to school on their own, and when they get into a little trouble - maybe they tease a friend too openly - then the nice lady walking her dog will straighten them out and make sure they walk directly and quietly to school. Should a youth fail to close a door between railway carriages someone down the carriage will wordlessly signal to him to go and close the door and he will obey without hesitation. Everyone walks home late at night in the dark and, while they do fear, I think few believe they will be attacked. When the Japanese are unhappy they do not attack their neighbours (at least not violently), instead, so as not to cause too much trouble, they kill themselves. People are always kind to foreigners, and help them find their way around, and they always compliment them with much admiration on their chop-stick use. Almost everyone is always kind and patient and tolerant, service in shops is perfection, motorists take great care around cyclists. People look after and honour their parents, grandparents and great grandparents. And at work, if you tell your secretary that a florescent high ceiling light is flickering and it is very slightly annoying, then a man in a blue jump suit will have fixed it 14 minutes later.

But within this idyllic society it is really hard to find the faith, hope, and love. Instead there is,

Fear: Before your exams you go to the shrine and put money in the coffers and write a prayer asking to pass your exams. The more money then the more likely you will pass. When at work it is decided that everyone must work certain hours you tell others that the guards on the gate are writing down when everyone comes in, even though, of course nothing of the sort is happening. You don't go into the tunnels (lots of tunnels in this hilly country!) at night because your friend told you that they saw a ghost in one.

Hopelessness: Even if you go to the top university (Todai), you do not consider politics as a career. Instead you believe you are powerless. You know that only the very rich can enter politics. Of course they are corrupt. It is best if we don't dwell on the bad things. There us nothing that can be done after all.

Obedience: When you grow up, you don't expect to fall in love. Indeed such a concept is very new and not very Japanese. Instead you hope your husband will be agreeable. Sounds to me like the much pitied Charlotte from Pride and Prejudice, too plain to hope to fall in love she marries for purely material peace of mind. An obedient woman is a beautiful woman. Women learn a slightly different language to men in schools and it leaves them unable to express anything very clearly, unless they use English. No worker, male or female, can disagree with their boss. All you can do is sit and wait to see what they might ask you to do. Although, if you have a British colleague you might go with them to talk to your boss, and then you can say (in English of course) "Julia thinks that...".

I feel a bit guilty, living with faith, hope and love within me and yet also able to enjoy all the nice things about Japanese society. Sometimes I feel like I am the only moderately happy person I know. Perhaps everyone else is just hiding their joy of living behind their reserve. I don't know. People coming to Japan have hoped for generations that some of the faith, hope and love may rub off but while the trapping of Western society have been adopted there has been quite incredible resilience to other fanciful notions. About 2% of Japanese are Christian. Just like the UK then, I used to think. However, I have far more faith and hope that British society can fix it's broken ways than I have that Japan can change. Although I cannot deny I still do have hope that some little of the "Western science way" will rub-off. I even see small progress, but the thing that worries me is it will not stick - as soon as we go home it will all be forgotten... hey anyone want to come and take over a very difficult mission? :-)

Probably this will make most readers of this blog all tetchy but I also think that it would be nice if atheists in the UK realised quite how much of the good stuff in their society they owe to Christian tradition.

When I first read it I though it was appalling and horrible but the longer I stay the more I admire the incredible insight of A.A.Gill's Mad in Japan.

A climatey tidbit for those who made it to the end - can you believe this!!! I can't! What about the actual actual poor? And where has she been to see the effects of climate change? The only place I have seen it is in London where people now eat outside on the pavement to better breathe the fumes. Oh - and I can also see it if I add "CO2" to my climate models. Then I see it really really well...

Monday, September 17, 2007

Comment on Schwartz

As I hinted, a group of us have taken a more detailed look at Schwartz's paper. It turned out to be quite interesting, in fact, and the results were not exactly as I had anticipated in my first glance.

In a nutshell, Schwartz assumes the climate system can be reasonably approximated as the simplest zero-dimensional energy balance model forced by white noise plus an anthropogenic trend, and further that the relevant parameters of this model (time scale and heat capacity) can be estimated from observed time series of surface temperature and ocean heat content.

There's a detailed post up at RealClimate which mostly focusses on the inapplicability of this energy balance model assumption - I'm sure that even Schwartz would admit this is at best an approximation, and contrary to his claims, the data clearly don't look like they come from such a system. Therefore, the whole concept of a single "time scale" which describes the relaxation rate of the climate system to any and all changes in forcing is rather suspect at the outset.

However, we also found the rather interesting (to me) effect:

Even if the climate system really was a simple energy balance model, the estimation method gives highly inaccurate and strongly biased answers anyway!

This came as a completely surprise - in my first post, I just assumed that the time series analysis method was well-known and gave accurate results as claimed. But it's simply not true.

I was right in assuming that the method for estimating the parameters of autoregressive processes was well established. What is also well established is that these estimates are biased, sometimes strongly so. Bartlett's Formula (which dates back to 1946) says that the sample estimate of the lag-1 autocorrelation parameter of a finite time series generated by an AR1 process converges to a random sample from N(r,sqrt((1-r2)/n)) as n (sample length) tends to infinity - that is, the distribution of samples converges to a Gaussian distribution centred on the true value, with a reasonably narrow width. But this is the asymptotic distribution for large n, not the actual distribution for a specific finite n.

The observational time series of annual average global surface temperature as used by Schwartz has 125 points. If the real time scale was 30 years, then that means the AR1 parameter r=exp(-1/30) is 0.967, and so Bartlett's Formula says the estimate should look like a sample from N(0.967, 0.02). This has a 95% probability interval of about 0.92 - 1 (actually the formula goes above 1, but this is a hard upper limit for the observed sample correlation). However, there is also a long literature (dating back to Orcutt 1948, only 2 years later than Bartlett's original paper) observing that there is a bias in the estimate. For the example above, the actual results obtained from Monte Carlo sampling have a 95% range of 0.82 - 0.97 with a median of 0.93. Someone has actually produced a formula for the bias of the mean, which is given by -(1+4r)/n, or about -0.04 in this case. This agrees well with our experimental results, but the much larger uncertainty (compared to Bartlett's Formula) is also worth noting.

Here's a graphical representation of that point. The blue curve shows the anticipated results according to Bartlett's formula for the case r=0.967, n=125. The red histogram shows the results that are obtained in practice for the sample lag-1 autocorrelation of AR1 series with the same parameters.

That result is just for the first lag, but similar results can be obtained for higher lags too.

When turned back into a time scale (via tau = -1/log(r)), the 95% probability interval of Bartlett's formula ranges from 12 up to infinity. So that's quite a wide range, but at least it is centred on the true answer of 30y and it doesn't get very close to 5y (due to the log transform, 12 is a long way from 5). But the 95% probability interval of the experimental answer ranges from 5 to 36 years with a median of 13! So it's hugely biased and barely reaches the true value.

In the submitted comment we show the results from a set of experiments with the simple energy balance model that Schwartz uses. Whether we use realistic forcing and detrend the results as Schwartz did (upper panel) or just white noise with no detrending (which results in a pure AR1 series, giving the results shown in the lower panel) the results are basically the same. In all cases, if the intrinsic time scale of the model is long, there is a strong bias in the estimate and observing a result as low as 5y is quite plausible even for a true time scale of 30y (corresponding to a sensitivity of 6C for doubled CO2) or more. Again, these results are insensitive to various details such as the amount of noise added and which lags are examined.

We also looked briefly at the outputs from the IPCC AR4 models, which are shown in the top panel. When applied to their simulations of the 20th century, the method returns a "time scale" that is much lower than the true relaxation time scale of the models which is known to be of the order of decades. Assuming a plausible heat capacity (and we don't fault Schwartz on that), these erroneous "time scale" estimates will generate unreasonably low estimates of climate sensitivity. This was thoroughly checked with an ensemble of GISS model runs, the analysis of which did as expected generate strongly biased estimates of sensitivity (3-20 times too low compared to the real answer). We didn't wade through the mountain of data necessary to check this with all models but the IPCC AR4 already says that they generally mix too much heat into the ocean (meaning a high heat capacity) so it is clear that this method will tend to generate strongly biased estimates for them too.

In conclusion, even if it was reasonable to approximate the climate system by a simple energy balance system (which the data refute) then Schwartz's estimate of 5+-1y for the time scale is not supported by the analysis - the estimation method is intrinsically biased and much more uncertain than his numbers suggest. In a wide range of numerical experiments where the time scale is known, the time series analysis gets it badly wrong. In short, this "time scale" analysis does not generate a useful diagnostic.

Some people have suggested that Schwartz didn't really believe his result, he was just putting it out to be shot down. Well, he has been touting this for some time - here is his abstract from the AGU meeting last year. and the manuscript has apparently been doing the rounds too. In fact another climate scientist contacted me through email to say that he'd tried to explain that it was wrong, and got nowhere, but perhaps he did not find as compelling a criticism as we think we have produced. So I was wrong to presume that Schwartz hadn't spoken to anyone in the field, but there is not much point in talking to people if you are then just going to ignore them! Based on my limited email interaction, Schwartz still seems convinced he is on to something that the rest of the world has overlooked. But we will have to wait and see how he responds in writing.

Sunday, September 16, 2007


It's that time of year again, when the higanbana (also called equinox lily, spider lily, or even hurricane lily in the hurricane belt of the USA) spring from nowhere. Mostly they are red but here's a white one for a change, in the peaceful Zen garden at our local temple Zuisenji.

Not really so peaceful when there are cicadas screeching all around! That's just one by itself, they are fading away now but for the past few months it has been quite a cacophony.

Kanji are crap

Readers may not have heard about the latest Japanese pension scandal, which helped to bring down the PM. Roughly 50 million account details in the national pension have been lost, meaning a whole lot of people risk not getting what they are due.

Here's an amusing snippet from a recent newspaper article:

The Social Insurance Agency failed to enter names for more than 10 percent of the 50 million public pension accounts whose rightful owners are now unknown apparently because the kanji characters created too much work.


The agency said employees had failed to enter the names likely because figuring out the proper kanji for account holders' names was too enormous a task.

So 5 million people have lost their pensions because the officials cannot read and write kanji properly (names are particularly difficult, not that this excuses simply abandoning the accounts).

I'm sure they would agree it's a small price to pay for such a "beautiful" language.

Wednesday, September 12, 2007


I've eaten some weird stuff here but this....

...takes the biscuit. Or the rice cracker.

Sunday, September 09, 2007


Perhaps I should have titled this post "Let's Forest!" Yesterday we went for a wander in the local hills to see what damage the typhoon had done. Our immediate neighbourhood is really well sheltered so it is always hard to tell how strong the wind is.

We soon came across a mass of branches blocking the path. Scrambling around the side we got to the following:

The old path runs straight up the middle of the picture (in fact the steps cut into the rock are visible).

I'm going to spend the rest of the weekend thinking about whether it made any noise.

Saturday, September 08, 2007

Let's Zen

Spotted in a local temple (the elegant Kencho-ji, one of our favourite destinations for a walk through the local hills).

(It's a poster advertising a weekend retreat there. The squint photo is to minimise flash glare, not because I can't get things straight.)

Pile on!

It seems like everyone is having a go at Steven Schwartz these days: based on the links to my earlier post - and the "lurkers who support me via email" :-) - my commentary on his recent climate sensitivity estimate met with general approval (more on that later), but this post is about his own commentary on the IPCC report that I noticed previously in Nature (available here).

I didn't want to distract myself before by fisking it in detail, but it seems largely misguided. His opening sentence "The latest report from the Intergovernmental Panel on Climate Change assesses the skill of climate models by their ability to reproduce warming over the twentieth century..." is obviously wrong and the article does not improve much from there. There is a whole chapter (number 8) explicitly dedicated to assessing model performance, there is another chapter (6) on paleoclimate, and large parts of chapters 9 and 10 are also concerned with how we gain confidence in projections/probabilistic predictions. While 20th century climate change detection and attribution does get (IMO) a slightly unhealthy prominence in the report as a whole, it is hardly the whole story - indeed it has long been known that merely matching the general temperature trend is a rather weak test of model performance at least for the longer term (one detail that is worth noting is that all plausible models indicate a roughly linear trend over say 1980-2030, which does contribute to our confidence in a continuation of the recent warming trend).

A response from several IPCC authors has just appeared here, together with a brief rebuttal from Schwartz. The IPCC authors point out a number of reasons why Schwartz is wrong, and in his final rebuttal all he does is repeat his original erroneous claim that "in assessing the skill of climate models by their ability to reproduce warming over the twentieth century, the latest report from the IPCC may give a false sense of their predictive capability". It's just not true.

Coming soon: more on Schwartz and that sensitivity estimate.

Thursday, September 06, 2007


It's a bit damp here.

That little dark dot in the middle....that's where I live (pic from the asahi weather site).