Friday, February 01, 2008

Corbynwatch: The Verdict

So, January is over, and it's time to see how Piers Corbyn did. Remember, he predicted that it would be bitterly cold, in fact one of the coldest 6 years in the last 100, with an average temperature of no more than 0.8C.

The numbers are in...and the average temperature was a whisker over 7C according to the pseudo-CET web page. P Lewis says the real value is 6.7C,which would make it 5th warmest in the last 100 years, or 8th warmest in the last 350 years. Now it's important to note that I'm not claiming that this has any strong consequences for our understanding of global warming - it's just one month in one region, and in fact most of the 7 warmer Januaries were a long time ago. What it does bear on is the validity of Corbyn's "Solar weather technique" for prediction. This forecast was just about as spectacular a failure as it is possible to have. It certainly wasn't a near miss, in fact it wasn't even a bad miss. Had he been shooting for the goal at Wembley, he'd have ballooned it over the Hamden Park. The 5.9C error (and note that 0.8C was the upper limit of his forecast, he said "close to freezing - 0.8C at best") is about as big as the difference between January and late April / early May. It wasn't just the temperature he got wrong, either - precipitation was not "well below normal" but actually extremely heavy, with many areas flooded.

He even revised his forecast in the middle of the month, claiming to have discovered a "data procedure error" - stirring his tea-leaves in the wrong direction, perhaps? - but even so, he blue-inked: "the forecast for some very cold weather in the later part of the month remains". Perhaps he meant to write "remains wrong". In fact the 2nd half must have averaged about 8C, since the running mean was just below 6C at that time.

But no doubt when he next makes some silly "prediction", the same journalists will lap it up and report it uncritically again. And if he keeps on predicting 5% events, then every so often one will come true, at which point he will be able to dine out on it for months...

He has just made his February forecast for the UK public. Once I've extracted the quantitative features from his vague verbiage, I'll report on that too.


P. Lewis said...

Further to the info elsewhere hereabouts, the Met Office CET data currently gives January average CET as 6.6°C. I'm unsure how this relates to the data at, which is presumably from some paid-for data feed from the CET bods, and whether or not this may be revised (up or down). It makes not a jot of difference to PC's forecast error though.

Some Met Office CET Jan data for info/context:

1916 7.5 **** 1838 -1.5
1921 7.3 **** 1881 -1.5
1796 7.3 **** 1709 -1.5
1834 7.1 **** 1776 -1.6
2007 7.0 **** 1716 -2.0
1733 6.9 **** 1963 -2.1
1975 6.8 **** 1740 -2.8
1983 6.7 **** 1814 -2.9
1898 6.6 **** 1684 -3.0
2008 6.6 **** 1795 -3.1

skanky said...

Philip Eden uses officially reported data (I can't remember if they're SYNOPS, CLIMAT or other obs). The main difference between his CET & Hadley is described here:

More information can be obtained by emailing Mr Eden, he's normally very forthcoming.

BF said...

Good work!

Now repeat the exercise for Hanson, Jones, Gore and the IPCC. That way people might be persuaded that you are indeed credible.

At least Corbyn behaved honourably and wasted no time admitting he got his severe January weather warning wrong, whereas we are still waiting for the IPCC to explain how Michael Mann's fraudulent hockey stick managed to make it past "2,500 of the worlds leading climate scientists."

P. Lewis said...

Oh dear! It seems there may be an asylum escapee in the vicinity.

Erm? Weather? Climate?

A comparison with individual states' meteorological office monthly forecasts and their forecast methods would be apposite. Your diatribe doesn't meet that criterion.

One could use the term "intellectual pygmy", but I fear that may give you undue credit.

Oh, and it's Hansen. I hear you're needed back over at CA now. Bon voyage!

James Annan said...


When HC, Hansen, or others, get forecasts badly wrong (or right!) I'll certainly report on them. HC did fail with their prediction of a record hot 2007, but that was only ever a 60% probability statement - so its failure is hardly an indictment of their methods. It's probably safe to say that the next significant El Nino *will* bring a record high temperature.

cce said...
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