|2011-06-11 20:23:45||Phil Jones significant temp rise - ask for help & stats question!|
This is Robin from Carbon Brief in the UK, with a request for help! Some of you may have seen that the BBC reported an interview with Phil Jones in which he said that acc. to CRU figures, temperature rise since 1995 is now significant to the 95% level. We 've written it up at Carbon Brief - see here http://www.carbonbrief.org/blog/2011/06/global-warming-since-1995-statistically-significant.
The reason I 'm asking for help is two-fold - first as a young website, we are still building up our community of commentators, and over the last 15 hours or so that thread has been bombarded with skeptics (many of whom I suspect have nowhere else to go to write about this as the BBC post is closed to comments). We could do with some more scientific literacy to redress the balance. So if any of you fancied heading over there for a bit, I would be very grateful.
Secondly, a specific question on stats. A guy called Doug Keenan has 'rebutted ' the Jones statement, saying that the trend is NOT signifiicant using the methodology in the 2007 IPCC report (http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3sappendix-3-a.html). He says:
It looks to me that he has tried to get over this tricky problem by assessing it at the 97.5% confidence level and saying that he is assessing it at the 95% level! However I am by no means a statistician so I can 't feel 100% sure. If anyone out there has this expertise, and is able to post a rebuttal to Keenan on our site, then I think that would be a useful intervention, and again much appreciated.
I won 't have much chance to check comments on this thread today unfortunately as out and about but will be able to let comments through. Many thanks
The definition of statistically significant is somewhat arbitrary. First you have to define the threshold (usually 95%), then you may or may not add other effects like autocorrelation. I won't bother to check what Keenan did, it may also be correct. It doesn't matter.
|2011-06-13 13:08:19||Reframing the question|
I recommend not getting bogged down in technical, statistical issues as that just adds to the confusion. Then the public come away with a "he said/she said" impression and come away more confused than ever.
The most effective way to debunk misinformation is to provide an alternative narrative, a compelling story. In this case, the story is the denier tactic of trying to trap a scientist with a gotchya question, the climate equivalent of "do you still beat your wife?". Dana is writing up a blog post on this topic:
For the record, I concur with Riccardo about the poor job Phil Jones has done. You can excuse his confusing answer when he was first ambushed with the question. But a year later, he's still playing into the denier's hands. The issue isn't whether the 16 year trend has pipped the 95% threshhold or not. The issue is that deniers took a short-term trend with a 93% chance of warming and tried to sell it to the public as NO chance of warming.