"There is no cover-up going on.
"When you've got 100MB worth of emails from somebody's personal files, no doubt you can find sentences that taken purely out of context can sound really bad,"
Well OK. Here's an e-mail from Phil Jones to Kevin Treberth on which Renwick was copied. This is the whole thing so nothing was taken out of context, and it sures looks like the climate change cabal is trying to cover up the sloppiness and inexactitude of their underlying data.
Kevin,
I will be around tomorrow (so Dec 21) until Dec 23 inclusive. Then again from Jan 3.
I will be checking email during the break from Dec 28 onwards. Are you in control of the glossary additions and modifications?As to change of base period - this seems like a decision for the whole of WGI. To redo the global temperature average, I can just move the series up/down, but this isn't the correct way to do it. I should talk out a new base period from all the individual stations and recalculate anomalies for the oceans. For the oceans this isn't a problem, but the land it is a serious problem. Many stations have good (i.e. near complete base periods for 1961-90) but I'll lose hundreds, maybe over a thousand, stations if I went to 1981-2000.
For both surface temperature and precipitation we don't have spatially complete datasets(like models) so it will be quite difficult. For the circulation indices(like SOI and NAO) based on station pairs there is a variance term(SD).Some of the character of the series will change. We could easily adjust all these series by simple offsetting but it isn't doing it properly. I'm in the throws of a project with the HC checking all the 61-90 normals we have for series that are incomplete, to ensure we don't have any biases. This has taken quite a time and I don't want to waste the effort.
The arguments of Albert and Dave make a lot of sense-continuity with the TAR etc.These sort of things can be explained,but then the FOD will not be compatible with all the papers we are referring to. This will lead to lots of confusion. I would like to stick with 1961-90.I don't want to change this until 1981-2010 is complete, for 3 reasons : 1) We need 30 years and 81-10 will get all the MSU in nicely, and 2) I will be near retirement! 3)is one of perception.As climatologists we are often changing base periods and have done for years.I remember getting a number of comments when I changed from 1951-80 to 1961-90. If we go to a more recent one the anomalies will seem less warm-I know this makes no sense scientifically, but it gives the skeptics something to go on about!If we do the simple way, they will say we aren't doing it properly. Best idea might be to show some maps of 1981-2000 minus 1961-90 to show spatially where it makes a difference for temp and precip. Showing it is quite small and likely within the intermodel differences for years which are only nominally 1981-2000. This might keep both sides happy.
We also probably need to consider WGII.Also the paleo chapter will find 1981-2000 impossible.1961-90 is difficult for them but not insurmountable.
Cheers
Phil
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