Losing the plot

Lucia lost the plot some time ago, mostly by cherry-picking her time period, using a weird data-fitting method and failing to understand what she was looking at. Now RP Jr follows her down the rabbett hole and bizarrely describes her post as “clear”. Well, when people are telling you what you want to hear you’re apt to approve.

As usual, you’re better off avin a larf with James . Though if you’re tired of slapstick, maybe reading the truth at RC would be more useful. I prefer bluetooth myself nowadays 🙂

[Update: it gets worse. Roger is losing his temper, and unfortunately hasn’t found somone to ask about stats. Although in fact its not really a stats question, its a climate modelling question.You can’t compare the trends from different model realisations with 5 different estimates of the same observational period. To try to understand this, suppose all 5 obs estimates were really really close together – they could be, if all the methods were near equivalent. Then the SD would be very small. But the models, because they aren’t simulating the same real years, will maintain a large spread. Their statistics will be different, and unknowing black boxes will declare them different -W]

Sea ice minimum kerfuffle

The summary of betting on sea ice refers. If you look in my comments, you’ll find any number of well intentioned people advising me that its time to close up the bets before I take a bath. But I haven’t. Anyone wanting to pile in is still welcome (if you can’t be bothered to look up the previous post the bet is simple: will this years Arctic sea ice extent minimum, as measured by the satellites, be less than last year? I say no).

i-1d2ce34f718bcf56cbda166133ef631c-N_timeseries.png The May 5th version of “Arctic sea ice news and analysis” provides some more fodder. I’ve ripped off a pic from them which I like. To me, it rather suggests no record this year. They somehow convince themselves that it does suggest a min. Hey ho, we’ll find out in a few months. Their section on “Estimating September extent based on past conditions” is cute. I like it; its a nice idea. Totally lacking, of course, is how would this idae have fared if applied last year, or the year before, or…

My personal opinion remains that we simply can’t forecast year-to-year variations with any degree of reliability. The long-term trend is clearly downwards, and there will be a new record sometime. But based purely on the behaviour of the sea-ice extent timeseries I still consider that new record this year is less than 50% likely. I also wonder if people aren’t in some danger of getting a teensy bit carried away publishing these “forecasts” which they don’t really believe. They are speculative prognosticaions, no more.

Andy Revkin (its him again!) covers this. In the comments, Bill Chapman is reported to say “I say the odds favor a new NH record minimum – put my money there.” I’ve replied (#40) but haven’t heard from him… I must give him an email. [update: I did. He declined -W]

[Update: via Gareth I discover this rather useful picture, which puts the present year more into context. It gives me hope for my bet. So, if you’re still interested… -W]

Betting on climate change, again?

As I said before, I don’t think much of the latest prediction of cooling. But apparently , the authors take it seriously, and believe it as a prediction (pers comm). So RC has decided to see if they are serious. My expectation is that they will find some spurious excuse for wimping out (I’ve offered to put up $100 on the bet not being taken, with me paying out if it is taken; any offers?).

Andy Revkin covers this. The only complaint I have is that JA is being airbrushed out of the picture. Such is life.

Coming soon: betting on sea ice.

[Update: I *can* spell climate -W]

Who am I?

Next to Al Gore, William Connolley may be the world’s most influential person in the global warming debate…“. It would be nice; sadly its only the opinion of Lawrence Solomon, who is, errrrm, not very well informed.

LS’s attempts to make sense of the innards of wikipedia are quite funny, for an insider – his confusion of KDP with Tabletop, for example. But I suspect thats rather in humour. If you’d like some more, then the list of cabals is good, as is WP:GIANTDICK, which for bonus points seems to be subject to a minor edit war: Replacing Nixon with a nuclear missile is a fine edit comment. And for weirdness, WP:SPIDER is worth a look.

The malign Nature effect, again

All the blogosphere is abuzz with Advancing decadal-scale climate prediction in the North Atlantic sector. I don’t have much to say that JA hasn’t already said. But that isn’t going to stop me saying it.

Firstly they’ve done something very odd with the reference model data in fig 4. The std IPCC projections would be right on their obs verification (which stops in 1998 for some bizarre reason) and their “forecast” would be even more obviously an outlier. I assume that the black line on fig 4 must be their own model. Looking again, I’m really rather baffled how this can possibly be anything useful, because their model so obviously goes wrong after 1995.

Secondly, the Torygraph quotes them as saying Noel Keenlyside of the Leibniz Institute of Marine Sciences, Kiel, Germany, said: “The IPCC would predict a 0.3°C warming over the next decade. Our prediction is that there will be no warming until 2015 but it will pick up after that.” No, thats not what the IPCC “predicts”, and no, no-warming is not what your own model predicts. Just look at your own figure 4, you dolt. It quite clearly shows warming from 2005 to 2015.

Maybe we should read their own press release, entitled “Improved climate predictions suggest a reduced warming trend during the next 10 years” to which the obvious rejoinder is “in what sense, improved?” – in the sense that it got them into Nature? They say To date climate change projections, as published in the last IPCC report, only considered changes in future atmospheric composition. This strategy is appropriate for long-term changes in climate such as predictions for the end of the century. However, in order to predict short-term developments over the next decade, models need additional information on natural climate variations, in particular associated with ocean currents

Whats weird here is there total lack of reference to Smith et al. Or maybe it isn’t so surprising. Smith et al have already done what they’ve done, except better. Mind you, it was published in Science, and the me-too effect may account for why this has got into Nature. Presumably the passing reference to assimilating ocean currents justifies their novelty; otherwsie they would have mentioned SSTs.

They go on The improved predictions suggest that global warming will weaken slightly during the following 10 years but their own figure 4 shows no such thing! (but its better than the no-warming-till-2015 junk that the lead author is quoted as saying). Connect the dots from 2005-2015 and you end up with 0.2 oC/decade, which is fairly standard. Maybe the annual data shows different, but they don’t show that. Why are people lapping this stuff up without even comparing the words to the figures?

Conclusion: this appears to be a mildly interesting study, which may have some slight novelty although not much. But it looks to me like the obvious model flaws mean that it doesn’t tell you anything useful about the real world, and it shouldn’t be getting the publicity that it is.

[Update: well, it made R4 at 10 o’clock. They had that David King on. Sigh. Fairly clear that he’d read the press release but not the paper, and fell into the obvious holes -W]