cc: lbutler@ucar.edu, k.briffa@uea.ac.uk date: Wed, 2 Jun 1999 11:19:35 -0600 (MDT) from: Tom Wigley subject: Re: Paleo and Balling to: Phil Jones Thanks, Phil. I've faxed a copy to Tom in Copenhagen. Lisa On Tue, 1 Jun 1999, Phil Jones wrote: > > Lisa, > Tom requires this for a public debate he's having with > Michaels and other skeptics on June 7. He tells me he's in > Denmark at the moment. I couldn't get something to him yesterday > as it was a holiday here. Can you forward the reply to him ? > > Cheers > Phil > > Tom, > Keith's in the Ural mountains for the next two weeks. You > probably emailed Malcolm re this one Utah chronology. As you say > this is one chronology, but Balling shouldn't have reconstructed > ANNUAL temperature. This may only work as the growing season is > part of the year. Malcolm may know if this is a good site for > temperature, also what standardization, if any, was used. Balling > doesn't say what r-squared he got or anything about Calib/Verif > or why the tree width series was deautocorrelated. So I would > say single site is the main point to make and his detail-less > calibration. Balling wouldn't accept a global/hemipsheric > temperature series based on one station - so why accept one > based on on tree series. He quotes an r value of 0.45, which is > not very high ! > > Looking at Balling's figure (#1) it would seem from the skew > of his reconstructions that he has an inverse relationship > with temperature (ie it's really precip that the trees respond > to). I would expect 'real' annual temps in Utah to be -vely > skewed. Ring widths will be -vely skewed. He has +ve skew in the > reconstruction, hence the presumed inverse relationship. Despite > his small r value of 0.45, he has quite a range in the > reconstruction. I would doubt whether Utah could get 4C warmer > in a year. > > If you use many more proxy series ( tree rings/ widths, ice > cores, historical etc) then you get a different view of the > past 1000 years. The papers to mention are > > a) Jones et al (1998) in The Holocene 8 467-483. > > b) Mann et al (1998) Nature 392 779-787 and GRL(1999) 26, 759-762. > > c) Briffa et al (1999) Science compass piece in early May. > > All 3 use different sets of paleo series ( Jones 17 long series, > Mann about 100 and Keith about 400 density series). > > All conclude that 20th century is the warmest of the millennium > and the warming during it unprecedented since 1400. All > centuries this millennium are cooler than the 1961-90 base > period - the 20th by about -0.05 and the 17th (coldest) 0.5 > below 1961-90. Warmest century in the first half of the > millennium was about 0.1-0.2 below 1961-90. Range of values > of decades over the last 1000 years is quite small - 1990s > about 0.35 and 1601-1610 -0.7. Even the coldest year of 1601 > was only about 1 C below 1961-90. This level of variability of > hemipsheric average temperature is in accord with the long > model control runs and the few runs with solar forcing since > ~ 1650. > > Hope this is of some use. > > Cheers > Phil > > > Prof. Phil Jones > Climatic Research Unit Telephone +44 (0) 1603 592090 > School of Environmental Sciences Fax +44 (0) 1603 507784 > University of East Anglia > Norwich Email p.jones@uea.ac.uk > NR4 7TJ > UK > > ---------------------------------------------------------------------------- > > > ********************************************************** *Tom M.L. Wigley * *Senior Scientist * *National Center for Atmospheric Research * *P.O. Box 3000 * *Boulder, CO 80307-3000 * *USA * *Phone: 303-497-2690 * *Fax: 303-497-2699 * *E-mail: wigley@ucar.edu * **********************************************************