cc: calvert@unixg.ubc.ca, k.briffa@uea.ac.uk, rbradley@climate1.geo.umass.edu, weaver@ocean.seos.uvic.ca date: Tue, 3 Aug 1999 17:41:02 -0400 (EDT) from: mann@snow.geo.umass.edu to: pedersen@eos.ubc.ca Dear Tom, Thanks for bringing that to our attention... I checked out that page and, unfortunately what he has done is *so* ridden with problems that it isn't even worth confronting. Many of us (e.g., me, Phil Jones, Henry Pollack, Shao-Yang Huang, Rob Harris, and others) have been scratching our heads trying to find a statistically defensible way of combining the information in boreholes and "conventional" proxy indicators, and as yet it is not clear if it can be done, given in particular the loss of information due to geothermal diffusion, and the overriding important of land-usage changes and snowcover variations, on borehole temperature profiles. I don't think Hoyt has added anything scientifically productive in this regard. Looks more like he has wrecklessly convoluted borhole data with our reconstructions to get just the kind of result he wants to get... Of course, there are issues with regard to secular trends in dendroclimatic reconstructions (which form an important, but not exclusive, role in oure reconstructions) and nobody is better qualified to discuss these than Keith, or Malcolm Hughes, who have highlighted these issues in recent publications (there is a link to a nice recent "Nota Bene" Science piece by Keith and Tim Osborn on my webpage: http://eclogite.geo.umass.edu/climate/mike/mbh99.html With regard to "Co2 fertilization", it is ironic that Hoyt frames his analysis in these terms, when it precisely this effect (for better or for worse) we took great pains to account for in our recent millennial temperature reconstruction (see the above web page for more info). At least, we have done this in a reasonably statistically-defensible, if imperfect, manner, rather than an ad hoc attempt to get an answer, rather than follow a scientifically meaningful process. This thing wouldn't have a chance at passing peer-review (at least, not on this planet), so he posts it on the web--the downside of absolute freedom of dissemination I suppose. The material in question is the scientific equivalent of trash, plain and simple. Like a lot of the "skeptics" out there, D.H. appears far less interested in honest scientific discourse, than in misleading as many unlucky soles as possible who wander into his den of disinformation (kind of like the "scientist" equivalent of an Ant Lion I suppose). Every once and a while, I do choose to respond to this type of crap (e.g., with regard to Pat Michaels--my soon-to-be "neighbor"'s recent pieces in his "World Climate Report"). In D.H.'s case, I doubt even more that this would be at all productive. We just have to wait and see if he ever tries to get this kind of thing published in the peer-reviewed literature. For our part, I think the best approach is to, as Jonathan Overpeck has so effectivley been doing, try whenever possible to educate the lay public about the essential distinction between peer-reviewed science and un-peer- reviewed...., well, whatever you want to call it. Again, thanks for the head's up on this. best regards, mike mann >X-Sender: tfp@pop.unixg.ubc.ca >Date: Tue, 3 Aug 1999 13:36:36 -0700 >To: rbradley@climate1.geo.umass.edu >From: Tom Pedersen >Subject: Skeptics >Cc: calvert@unixg.ubc.ca (Steve Calvert), k.briffa@uea.ac.uk, > weaver@ocean.seos.uvic.ca > >Hi Ray: >My colleague, Steve Calvert, has just brought to my attention a website of >which I was unaware but you probably know well. It's at >http://www.erols.com/dhoyt1 >and run by Doug Hoyt. >Amongst other things Hoyt has taken the Mann reconstruction and >reconstructed it by "removing the effect on tree ring thickness that >results from CO2 fertilization" (paraphrased). You will see the figure on >his site. He concludes that there is no significant warming in the last >half of this century relative to the last millenium. Do you know this guy? >Are you familiar with his reconstruction of your reconstruction? Didn't >Keith Briffa correct his tree-ring reconstructions for CO2 fertilization? >[Keith: any comments?]. Steve and I would be most interested to hear your >collective comments... > >To close this, here is a bit cut and pasted from Hoyt's sight: > > > Three Final Points > >There are three important points to make about the reported warming of the >last 20 years: > >1. The warming has occurred mostly at night and not during the day. This >result is inconsistent with a warming >caused by greenhouse gases, but is consistent with urban heat island and >other surface effects. > >2. The reported warming has occurred only at the surface and not in the >upper atmosphere. This type of warming is >completely opposite to what is predicted if greenhouse gases are the cause. >Again these observations are consistent >with problems in the surface measurements. > >3. The warming has occurred primarily in the Northern Hemisphere >mid-latitudes with little in the polar and tropical >regions. This result is consistent with urban influences, but is >incompatible with the climate warming predicted from >greenhouse gases which predict it to be largest in the polar regions. > >In short, the reported warming is inconsistent with warming due to >greenhouse gases in its temporal, vertical, and >geographical distribution. The reported warming is consistent with problems >in the surface network. > > >Cheers, Tom > > >T.F. Pedersen >Oceanography, Earth and Ocean Sciences, 6270 University Boulevard, >University of British Columbia, Vancouver, B.C. Canada V6T 1Z4 >Telephone: 604-822-5984 Fax: 604-822-6091 Email: pedersen@eos.ubc.ca >http://www.eos.ubc.ca/ > > _______________________________________________________________________ Michael E. Mann ________Current_____________________________Starting Fall 1999_________ Adjunct Assistant Professor | Assistant Professor Department of Geosciences | Dept. of Environmental Sciences Morrill Science Center | Clark Hall University of Massachusetts | University of Virginia Amherst, MA 01003 | Charlottesville, VA 22903 _________________________________|_____________________________________ e-mail: mann@geo.umass.edu; memann@titan.oit.umass.edu (attachments) Phone: (413) 545-9573 FAX: (413) 545-1200 http://www.geo.umass.edu/climate/mike