[jules' pics] 5/25/2010 06:06:00 PM

shirakoma ike at sunrise, originally uploaded by julesberry2001.

James says, "the eyepads don't help much when one's wife decides we must get up and photograph the sunrise anyway. "

[BTW - this week's blogged fotos from last weekend's mountain trip (Monday,Tuesday, Wednesday) are all taken with James' wee LX3.]

--
Posted By jules to jules' pics at 5/25/2010 06:06:00 PM

[jules' pics] 5/24/2010 08:50:00 PM

ipad, originally uploaded by julesberry2001.

Some people on the internets have suggested that ipads are of little practical value. That would be very wrong. In Japanese mountain huts, where the sun rises through the bare windows at 5am, they not just a luxury but a necessity.

--
Posted By jules to jules' pics at 5/24/2010 08:50:00 PM

Going down...

The fall in Japan's population is accelerating pretty much as expected:

Japan's population has entered full-scale decline and shrank by a record 183,000 people over the past year

Of course this is accompanied by a "greying" of the population and reduction in the workforce as a proportion of the total. One rational response might be to encourage immigration to make up the numbers, but in fact Japan has been kicking out foreigners at quite a rate recently. The reduction in non-Japanese population actually contributed 47,000 to the total decline. This is all part of the current trend towards isolationism. Perhaps they think they can replace workers with robots.

Meanwhile, the economy has recently been back in deflation, though not by enough to make up for the pay cuts.

[jules' pics] 5/23/2010 11:37:00 PM

Iodake in a blizzard, originally uploaded by julesberry2001.

It was OK as long as we didn't walk into the wind. Unfortunately, down there in the white there is a junction at which we had to do just that. The path being invisible, we walked off the edge of the mountain in the snow hoping we would land on a path below. More accurately, James walked - perhaps he could even see where he was going - while I, eyes stinging and being blown around like a little leaf, clung on to him pathetically.

[Iodake summit, part of Yatsugatake, at about 7am and 2700m]

--
Posted By jules to jules' pics at 5/23/2010 11:37:00 PM

Another look at climate sensitivity

This is the title of an interesting paper by Zaliapin and Ghil that appeared some time ago on the Arxiv and more recently in peer-reviewed form in NPG. It's presented as a criticism of Roe and Baker, which has already been debunked enough, so after a quick glance I didn't pay too much attention to it at first. I also know the second author to be extremely clever, so I was worried that it might be really technical. On a second, slower, reading, however, it's actually quite straightforward and very interesting. It also seems rather harsh on R&B, because the criticism applies to a whole host of similar work.

Z&G start with the basic premise that R&B - and indeed all work of this nature - use, that there's a functional relationship between radiation R (at the top of the atmosphere) and the surface temperature T, which we can write as R=R(T,a(T)) where the notation indicates that a(T) is the "feedback" term, that is to say, if we replace a(T) with zero then the function returns the zero-feedback relationship.

We can then perform a Taylor series expansion to investigate how the radiation balance changes with temperature:

DR = dR/dT*DT + dR/da*da/dT*DT + O(DT²)

(read the real paper for more elegant typesetting)

By writing 1/L0 = dR/dT (L0 is the zero-feedback sensitivity) and defining f=-L0*dR/da*da/dT we arrive at the familiar expression

DR = (1-f)/L0 * DT + O(DT²)

Now what everyone does at this point is to drop the last term and use the linear approximation, which can be re-arranged to give

DT = L0/(1-f) * DF

exhibiting the well-known singularity for a feedback of f=1.

What Zaliapin and Ghil point out is really startlingly simple and IMO elegant. They merely observe that if f is close to one, the linear truncation was not justified because the quadratic term is now large enough to matter! Once it is included, the singularity at f=1 goes away, as their Fig 2 shows:

(The feedback factor f cannot be larger than one or the initial equilibrium is unstable, even with the nonlinear term, hence the upper bound on the x-axis is sound.)

I'm not yet sure how much this really matters. We can still get a high sensitivity so long as the nonlinearity is small. AIUI most models do show a fairly, but not perfectly, linear response over quite a range of forcing and temperature, and the existence of complex climate models with sensitivities above 6C implies that such high values are at least not a mathematical impossibility. It may, however, make it harder to justify the sort of pathological "long tail" arguments beloved by some. Of course I've argued against them on a number of grounds already - not least of which is that, from a policy perspective, we are on really shaky ground if all the calls to action have to be based on highly improbable events that we are pretty confident won't happen irrespective of what mitigation we do or do not attempt. In any case, the maths is interesting in its own right.

[jules' pics] 5/19/2010 10:52:00 PM

Takayama, originally uploaded by julesberry2001.

Maybe the last picktur I'll post from "real Japan", this one is of a restaurant in Takayama that we didn't go to. Instead we had a very memorable meal of prime beef tonkastu*, but I didn't photograph the probably equally good looking restaurant as I was too busy negotiating our entry to the establishment.

*It was a real treat because normal tonkatsu restaurants in our region of Japan don't serve beef, just pork and jumbo shrimp.

--
Posted By jules to jules' pics at 5/19/2010 10:52:00 PM

New Michelin guidebook to cover Yokohama, Kamakura

Apparently the next Michelin guide to Tokyo will also cover Yokohama and Kamakura.

When Michelin first brought out a guide to Tokyo a few years ago, there was much brouhaha (also here) about how foreign barbarians couldn't possibly be able to properly judge Japan's uniquely unique haute cuisine, and they seemed to hand out stars like confetti, especially to the sort of absurdly pretentious places where you need a personal introduction in order to even be admitted into the restaurant.

I have to wonder what they will find in Kamakura to be worthy of Michelin stars. I mean, I very much enjoy some of the restaurants here - it is far better than you'd find in any normal Japanese town this size, presumably due to the huge numbers of day-trippers and foreign visitors - but there is nothing that I'd really associate with Michelin stars.

Anyway, I'll be interested to see what they say - and maybe they will have one or two new suggestions for us to try.

[jules' pics] 5/17/2010 08:36:00 PM

Takayama, originally uploaded by julesberry2001.

Old-timers* in old-time Japan. The streets of "Real Japan" were full of Germans and Brits. I think this was why it did not feel very real to me. Nevertheless, it is certainly worth a visit.

[*actually in-laws!]

--
Posted By jules to jules' pics at 5/17/2010 08:36:00 PM

Bounds, climate sensitivity, and costs of climate change

Hot on the heels of our paper (which is still languishing in the publishing queue, though published on-line) I was rather surprised to come across another paper recently talking about upper bounds on climate sensitivity, and the costs of climate change. It is open access, so you can all read it for yourselves. The authors consider the "long tail" of possible temperature change and how this influences the economic analyses of climate change. They point out that the pathology of Weitzman's result vanishes if an upper bound on climate sensitivity is imposed. They use a Cauchy distribution for sensitivity, and show that the optimal climate policy is fairly insensitive to where this bound is placed, within the range tested of 20-50C. However, they don't appear to justify why these bounds should be used, rather than (say) 500C or 500,000C, at which point the results would probably be rather different.

Though the authors appear to not know about our Climatic Change paper, they actually do cite two of our other papers, in a way that I'm not really enthused by. They interpret us as explicitly ruling out a value for sensitivity greater than 8C, where in fact all of our results are probabilistic and do not arrive at an absolute value (other than any assumed in the prior). But this is only by way of a throwaway comment at the end of their paper, and isn't in any way central to their argument.

Coincidentally, Myles Allen and co are also going on again about how the Jeffreys' Prior solves all the problems of subjectivity (see here for previous). The whole enterprise appears to be a dead end to me and as far as I can tell, they haven't actually demonstrated any practical results, but maybe when he has eliminated all other possibilities he will reluctantly come around to embracing the standard Bayesian interpretation of probability. At least while he is presenting abstruse technical notes on the Arxiv he isn't causing more trouble elsewhere, and it must now be increasingly difficult for him to defend his previous claims. This could make life a little embarassing for the next IPCC report if people don't start producing climate sensitivity estimates that are not based on the now thoroughly discredited uniform prior...

[jules' pics] 5/16/2010 09:46:00 PM

Takayama, originally uploaded by julesberry2001.

More "Real Japan". Genuine, Edo period (1603 to 1868) vending machine.

--
Posted By jules to jules' pics at 5/16/2010 09:46:00 PM