Today is the solstice, hurrah, days get longer from now on. And we’ve just come through our first hard frosts of the winter into Fog. So here is a joke, told to me by Daniel from his friend Adam:
One night, a butcher, a baker and a candlemaker are together in a locked room with barred windows and so on. Next morning there are four people in the room. How come?
Continue reading “Solstice Joke”
… as said by the wise CIP in the comments. Although I wasn’t quite sure how to interpret it. BTW, this is yet more Stern stuff – sorry.
So the first thing to say is… I’m not really happy expressing all this in terms of GDP. We could all be a lot happier on lower incomes if… well, if I was dictator of the world. If we hadn’t wasted billions invading Iraq and on the Child Support Agency and… I hope you get the point. Money isn’t everything.
But if we *are* discussing it all in terms of money, then we ought to notice the point that Tim Worstall has made – that the differences between A2 and A1B (SRES scenarios) are far bigger than 5%. So if we really want to maximise consumption (which is how Stern frames it) then we ought to push towards the A1 family… which is globalisation 🙂
OK, I’m desperately trying to understand Stern, and failing. Things just don’t seem to connect together properly. Possibly if I actually read the entire thing carefully… but who has the time. So, if anyone can explain to me:
Stern sez: Using the results from formal economic models, the Review estimates that if we don’t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more. But if you look at the damage-to-2100 from fig 6.5 (http://www.hm-treasury.gov.uk/media/8AC/CC/Chapter_6_Economic_modelling.pdf) *none* of the scenarios get to 5% mean damage by 2100. And if you take “at least” to mean “lower 5%-ile” then 1% damage is more plausible.
Figure 6.2 clearly shows that some models of economic effects show -ve damage for low T rise: up to 2 oC for one model. But by figure 6.5, all T levels lead to +ve damages. So some of these econ models have been thrown away. On what grounds?
[Update: JQ has an attempt to defend Sterns discount rates here (see linked preprint). I don’t find it convincing (nor does Tol) but it may be that there is rather more complexity to the choice than I thought. JA in the comments makes a bravce attempt to understand the issue.
To demonstrate how hard it is for the climate and econ side to talk together, JQ definitely gets it wrong when he says “A big problem with using Annan’s work to discuss Stern is that the two are talking about different things.” – they are, slightly, but that doesn’t stop it being relevant, and suggesting that Sterns numbers are too high. JQ talks around that a bit, but fails to get the point -W]
NERC has a bold new initiative… the NERC Climate Change Challenge. As they say Scientific evidence demonstrates clearly that human activity is changing the planet’s climate. But there are still sceptics who dispute the data and its interpretation. If you don’t believe the science, please tell us why and we’ll respond to your challenge. Or you can have more detail. There isn’t much there yet, so I think Lubos should pile in.
Since they lean on the Stern report, I thought it would be fun to ask them about high climate sensitivity. Maybe they will ask James as one of their experts to reply… :-). Ah no, I’ve just found the Team of Experts: Professor Alan Thorpe, Professor Julia Slingo, Professor Peter Cox and Professor Colin Prentice. Obviously busy folk, because they haven’t found time to answer yesterdays inaugural question from… someone in Swindon.
I found out about this from the NERC internal magazine. I wonder how many sceptics read that, so I also wonder who else is likely to find out about this…
RP Sr has yet another post The Relevance of Nonlinear Effects In the Climate System pushing the usual stuff: Thus if we accept that small perturbations can result in significant changes in the climate system through nonlinear interactions, then all of the human- and natural climate forcings need to be assessed in this context. I would sigh and move on (I did, earlier today) but now I feel moved to find an old post of mine: Climate is stable in the absence of external perturbation. See, its so old its on the old blog…
Continue reading “The Irrelevance of Nonlinear Effects In the Climate System”
Or, perhaps more politely, ‘National interest’ halts arms corruption inquiry.
From the grauniad article: A major criminal investigation into alleged corruption by the arms company BAE Systems and its executives was stopped in its tracks yesterday when the prime minister claimed it would endanger Britain’s security if the inquiry was allowed to continue. The remarkable intervention was announced by the attorney general, Lord Goldsmith, who took the decision to end the Serious Fraud Office inquiry into alleged bribes paid by the company to Saudi officials, after consulting cabinet colleagues. In recent weeks, BAE and the Saudi embassy had frantically lobbied the government for the long-running investigation to be discontinued, with the company insisting it was poised to lose another lucrative Saudi contract if it was allowed to go on. This came at a time when the SFO appeared to have made a significant breakthrough, with investigators on the brink of accessing key Swiss bank accounts. However, Lord Goldsmith consulted the prime minister, the defence secretary, foreign secretary, and the intelligence services, and they decided that “the wider public interest” “outweighed the need to maintain the rule of law”. Mr Blair said it would be bad for Britain’s security if the SFO was allowed to go ahead, according to the statement made in the Lords by Lord Goldsmith. The statement did not elaborate on the nature of the threat.
The funny bit is in its statements last night the government said commercial considerations had played no part in the decision but I don’t think they are fooling anyone.
I was at the NCAS conference today (since it was in Cambridge it would have been impolite not to go). Tim “Da Man” Palmer spoke about, ermm, sort of a merge of NWP and climate scales. But thats not the point… the point is that he showed a stratification of the Staniforth CP.net PDF in terms of modifications to the entrainment scheme. Increasing entraiment, or leaving it unchanged, produced the low values (up to 6). All the high sensitivities (6-12) came from experiments in which the convective entraiment was reduced (also, although he didn’t mention this, all the high sensitivies had a distinctive level of difference from the std model climatology. Not expecially large, but remarkably constant).
“Reduced” wasn’t defined, but TP then went on to show some results from the ECMWF model in which it was reduced by 4/5. And what that showed was that when you did that within the assimilation framework, the reduced entraiment was completely out of balance. Ie, within that framework, unrealistic. TP immeadiately said that he wasn’t saying that the CP.net stuff was wrong; since it was a different model. But all the same…
Continue reading “Climate sensitivity factoid”
Having had a couple of comments on this, I realise that some of the required background on Bayesian statistics is waaaay over some peoples heads. This is probably no fault of theirs. Let me make some faint attempt at explanation, and James can correct me as needed, and doubtless Lubos will leap in if I leave him an opening.
The issue (at least in this context) is the updating of “prior” information in the light of new information. Prior information means (at least nominally) what you knew about, let us say, the climate sensitivity S before you tried to make any plausible estimates of it. If you want the maths (which is not hard) then James post applies, as does the rejected paper. In fact let me copy it here, perhaps it will help: f(S|O) = f(O|S)f(S)/f(O). f(S) is the *prior* probability density function (PDF) for the climate sensitivity S. f(S|O) is the *output*: the PDF of S, taking into account the observations you’ve just made, and the prior distribution.
So the output depends on your obs (so you would hope); and on what you knew before, the prior. The problem is that it is hard or impossible to construct a truely sensible “prior” (as James points out; but I don’t think its particularly contentious). You can construct a pretend “ignorant” prior by asserting that a uniform value between 0 and 20 is ignorant (U[0,20]). But (again, as James points out) this means that your prior thinks it is three times as likely that S is greater than 5 than it is less than 5. No one believes that. Inevitably, you are using some of your knowledge in constructing the prior. But hopefully not the same knowledge as you use to sharpen it up aferwards.
So the only hope is that your obs are sufficiently well constrained that the prior doesn’t matter too much. If your obs were S=3 (with absolute precision), this would be true. But the obs are S=3+/-1.5, where the +/-1.5 hides various different PDFs, so the prior matters. But still, if you apply enough obs then it still doesn’t matter too much, as each one sharpens up the result more. And if you do this, you end up rejecting any reasonable chance of a high climate sensitivity.
Did that help at all?
Says the latest Oxfam missive through our door. And their website has similar, sourced to the Stern report: ..the unfair way climate change affects people living in poverty. They are least responsible for the problem, have benefited less from levels of carbon use, but are paying the biggest price. The level of greenhouse gases in the atmosphere is historically a result of rich world activity. Therefore to be fair, the rich world should bear the full costs of adapting to climate change, at least in the early years.
People who give to Oxfam may well be supposed to be sympathetic to this (I am; though poor people have many other problems too). But (using this as an excuse to repeat one of my first points about Stern) I’m really not sure how well it works in the world at large. Do people who would do nothing, for their own sake, really think “I must cut back to help the poor”? It seems unlikely. It may even have the opposite effect. How altruistic are people, when it comes down to difficult choices? Maybe we all feel obliged to so at least something… so Oxfam may benefit from our guilt?
This post is just to get you to read James Annans post about: An Inconvenient Truth. Which is his (& Jules) attempt to get his paper about climate sensitivity published. Since the paper is sound, and sensible, and very clear and readable, and of clear wide interest, the question is why isn’t it published?
The best available answer seems to be that some people don’t like his rather clear demonstration that a lot of the talk about high climate sensitivity (hands up CP.net and Stern) is nonsense.
Another possibility is that he isn’t well known enough: this is the sort of basic paper that someone eminent in the field (sorry J+J) gets to publish and everyone subsequently references. It reminds me of a wonderful cartoon of a business meeting, all men, bar one woman. And the chair is saying: “thats an excellent suggestion Miss Smith. Perhaps one of the men here would like to make it?”.
[Some of the comments on this are getting a little heated; I’ve deleted one that was trolling. Please be polite]
