And potholer: http://www.youtube.com/watch?v=Qbn1rCZz1ow

David Rose is a caver with an excellent journalistic record on that subject, who I previously thought was a man of integrity. These articles have been a great disappointment to me and I've asked him what on earth he thinks he's doing.

[blockquote][cite=stemytea]32 data points, two of which are outliers. They have a nerve putting in 95% confidence Intervals [/blockquote]
They have done a fair amount of validation work though, eg these comparisons with ice thickness measurements taken from 2 submarines vs the model predictions.

It looks like the average is about right on the graph, but interestingly there's a distinct trend within the data for the model to underestimate the thickness for the thickest ice, and overestimate it for the thinnest ice.

It looks from that like the model they're using isn't properly calibrated to take account of the faster melting speed for thinner ice vs the thicker ice that's become apparent in recent years.

I'm not entirely clear if this is specifically related to the thickness of the ice, or that the thinner ice tends to mostly be around the edges of the pack, and therefore most vulnerable to melting from warmer sea water flowing below it / warmer air temperatures around the edges. I suspect it's maybe a bit of both.

http://www.agu.org/journals/jc/jc1109/2011JC007084/figures.shtml#fig02

Ed, you have a great knack - I'm following your blog full-time.

http://www.independent.co.uk/environment/snowfalls-are-now-just-a-thing-of-the-past-724017.html


"According to Dr David Viner, a senior research scientist at the climatic research unit (CRU) of the University of East Anglia,within a few years winter snowfall will become "a very rare and exciting event".

"Children just aren't going to know what snow is," he said.

The effects of snow-free winter in Britain are already becoming apparent. This year, for the first time ever, Hamleys, Britain's biggest toyshop, had no sledges on display in its Regent Street store. "It was a bit of a first," a spokesperson said.

Posted By: Ed DaviesSomebody said something twelve years ago which seemed plausible at the time but is now well understood to have been a bit silly, or at least very premature, and has been discussed a lot since. So what? This is getting tedious.

2nd that!

My partner says that in her life time it was always very rare/non existant to have snow at christmas where we are. She is very suprised that the last few years its become the norm almost.

Bot, you clearly think this of interest to the rest of us. Would you care to explain why?

Hint: more snow in some spots is entirely consistent with global warming. Two mechanisms spring immediately to mind. One is that warmer (less cold) air tends to pick up more moisture but if the temperature is still below freezing it can still fall as snow. This is why some glaciers are expanding. The other is that changes to surface conditions can affect the weather patterns. E.g., there's that research from Potsdam which seems to show that ice-free sea surfaces north of Russia are connected, via routing of the jetstream, to colder winters in Central Europe.

(BTW, where's “where we are”.)

Posted By: bot de pailleWhy was it plausible at the time

Hmmm, perhaps I should have said “less implausible” — we were still, more or less, in a period of steadily rising global temperatures having had the fairly recent highs in 1998, etc.

and what has changed and that is well understood that now makes it silly???

See my "hints" above.

...bearing in mind this came from a climate professor at the UEA CRU.

Yes, a bit disappointing but, still, even professors are allowed to express personal opinions which are not rigorously backed by the peer-reviewed literature. Maybe it's a case of his statement not being labelled as such clearly enough or the label falling off somewhere in the publication process.