What is the point of the CCSP Committee "Temperature Trends in the Lower Atmosphere-Steps for Understanding and Reconciling Differences"?

A reader enquires about my take on "his [RP Sr's] precipitous resignation as chair of one of the CCSP committees in the face of an apparent revolt by the members: http://climatesci.atmos.colostate.edu/?p=30".

Well now, its all very interesting. This is my excuse for yet another MSU post.

First, some pointers to other folk who got there first: Scott Church guesting at Tim "I'm banning you :-)" Lambert's Deltoid (BTW, RC's hit counter is now past 400k, and will overtake TL soon...). James "Slashdotted" Annan dislikes Spencers slurs (I agree). Chris Mooney points to a few other links and curiously praises the Economists article, which I though was poor. But he does point out the curious press release policy on the 3 ScienceExpress stories. Also (can't resist this) it turns out that Spencer is a creationist. Weird or what. Thanks TP.

My take (summary): this committee has been thoroughly overtaken by events and no longer mattters very much. So, scientifically, has the S+C MSU record.

More detail: one (perhaps even the only) of the untidy ends of the IPCC TAR was tropospheric temperature trends, which appeared to be observed to be lower than they should have been (if you believed the GCMs and the sfc records). The skeptics made much of this; most climate scientists were, I think, rather less worried: the record was short, obs have errors, it was a puzzle that would be resolved. See various MSU/S+C posts here.

The puzzle became less puzzling as even the S+C/UAH trends got larger, and other analyses (RSS; Vinnikov and Grody; Fu) got even larger trends, and pointed to probable errors in the S+C trends. Nonetheless there remained an interesting puzzle, and in 2003 a meeting was convened to discuss it - I think ES attended. The meeting didn't really resolve anything, which in retrospect was no surprise. But it did decide to write a report. The prospectus, including lead authors and chapter headings, is at http://www.climatescience.gov/Library/sap/sap1-1/sap1-1prospectus-final.pdf (the "final" is now amusingly wrong, since RP has resigned), all nicely modelled on the IPCC model.

But the problem is that the report has been overtaken by events. Skipping lightly over the history, the three recent papers in ScienceExpress (see Et Tu LT? - and note only 25 comments on this major subject - proof that people don't comment so much on real science :-() show that:

  1. The S+C trends were wrong, by a large margin, because they made a sign error
  2. The radiosonde trends may well be too low too
  3. Models predict about 1.3 times as much warming in the trop as at the sfc

That last point quantifies the "models predict more warming in the trop than at the sfc". This was true, but by no means a major prediction: you have to struggle through the TAR to find any figures showing it. So finally Santer et al have got round to analysing what the models actually do predict.

Point 2 (oh dear I'm going backwards...) is the result of analysing radiation corrections to the radiosonde (balloon) record. Sondes thermometers are subject to solar heating in daytime, and need correcting, and the corrections are to some degree uncertain. The sonde record has never been great. Sherwood et al. suggest that the sonde trend is too low: its early days for this idea yet, but it may well be correct.

Point 1 is the biggie. Mears et al. have worked out that S+C made a mistake in applying a correction to the UAH MSU record. Spencer just about admits this, but in a distinctly weaselly way (in particular "This particular error is within the published margin of error for LT of +/- 0.05 C/decade (Christy et al. 2003)" in http://vortex.nsstc.uah.edu/data/msu/t2lt/readme.07Aug2005 is just blowing smoke): as I understand it, its a simple sign error, but he doesn't admit that. S+C have now made an awfully large number of different corrections to their record, and if they were showing large warming the septic crowd would be howling for their blood for repeatedly adjusting their trends. S+C were the first, but there is no longer any reason for giving their record primacy - far from it: despite all the corrections, their technique is still not beyond reproach. RSS is probably better.

So (if you've read this far) where does this leave the committee? In limbo. If those 3 papers had been available in 2003, no-one would have bothered convene the meeting much less set up a report-writing committee. Had the committee mananged to report in a timely way, it might have been worth something, but not a lot, because the main point was the errors in S+C's dataset and possibly in the radiosondes. So perhaps its just as well its late. They will probably feel obliged to publish something, but maybe they should just not bother.

And where does this leave RP Sr's resignation? I don't have a lot of sympathy for his POV, which appears to be The current discussion in the media based on the three Science Express articles misses the more significant issue of spatial trends in tropospheric temperature trends. This is just wrong, at least in terms of impact: the overwhelming issue, which caused the committee to be set up, was the difference in global average trends. It may not have been RP's interest, which may be why he is so miffed, but it was everyone elses.


Anonymous said...

WMC's efforts deserve a comment.

The RVTT workshop was held with the goal of writing a report. There is an on-going report
writing process in the US Climate Science program, which it is claimed to be directed toward
answering questions about the science.


Here are the planning documents:


And the latest schedule for the reports:


As I pointed out when I attended the workshop, the whole process is driven by politics, which in
the U.S. has been taken over by the Republicans, who don’t want to admit that there is an
environment, let alone that mankind might be messing it up. They have managed to stretch out
the entire process into 2008. By then, Gee Dubyah will be on his way out of town. It’s the old
legal tactic of delay, delay, DeLay, IMHO.

William M. Connolley said...

It does look rather like deliberate delay, though in the end that doesn't look like it will matter much. The important bits came out in Science, or so it seems to me: is there much left?