date: Mon, 05 Mar 2001 17:20:13 -0500
from: "Michael E. Mann" <mann@multiproxy.evsc.virginia.edu>
subject: Re: RSB Broecker response
to: "Raymond S. Bradley" <rbradley@geo.umass.edu>, mhughes@ltrr.arizona.edu,  p.jones@uea.ac.uk, k.briffa@uea.ac.uk, tom@ocean.tamu.edu

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Ray,

Do Pollack et al really say that in the 2000 article you cite (I don't have 
a copy)? If so, how do they rectify w/ the conclusion to the contrary 
expressed in Huang et al '97???

mike

p.s. this is strongest either as a single authored piece (Ray only), or w/ 
*all* our names.
In the latter case, I am happy to be on board...

At 03:50 PM 3/5/01 -0500, Raymond S. Bradley wrote:
>Here's what I propose to send to Science.  I have just focused on a few 
>major points rather than trying to address all of the egregious errors & 
>distractions in his article.  Join me if you wish...but I don't plan to 
>spend much more time on multiple iterations!  I believe Scott Stine is 
>also writing a response (basically saying that what Broecker said about 
>his data is true, but irrelevant to the question he poses).
>ray
>____________________________________________________________________________ 
>__________________________________________
>
>Paleoclimate reconstructions (1-4) using all available climate proxies 
>indicate that temperatures were warmer in Medieval times than during the 
>subsequent Little Ice Age (~1550-1850).  But there is very little 
>evidence outside of Greenland and western Europe that temperatures in 
>Medieval times exceeded those of recent decades (5,6).  All studies of 
>large scale climate variations reveal regions which do not follow the 
>global or hemispheric trend (e.g. 7) so selecting a few data points, as 
>Broecker does, (8) adds little to resolving the question he poses (Was 
>the Medieval Warm Period Global?).  Furthermore, his claim that only 
>borehole temperatures and snowlines can reconstruct temperatures to within 
>0.5C is not supported in the literature.  Reconstructing global 
>temperature requires a geographically extensive network of data, not just 
>a few points.  Could you begin to appreciate the beauty and complexity of 
>a symphony by just listening to the percussion section of an 
>orchestra?  Studies that have listened to all the instruments that are 
>currently available (1-4, 9,10) conclude that 20th century warming is 
>unprecedented in both rate and magnitude, compared to the last 1000 
>years.  This view may change as additional records become available, but 
>that is the state of play right now.
>I could add:
>Medieval climate was clearly unusual in some areas (cite Stine) and 
>further regional studies are needed; these may help to determine if 
>Broecker's hypothesis of a change in thermohaline circulation holds water.
>[This may be too confusing an allusion for non-English Science readers!!]
>
>1.  M. K. Hughes and H. F. Diaz, Clim. Change 26, 109 (1996).
>2.  P. D. Jones et al., The Holocene 8, 455 (1998).
>3.  Mann, M.E., et al., Geophys. Res. Lett. 26, 759 (1999).
>4.  T.J. Crowley and T.S. Lowery, Ambio 29, 51 (2000).
>5.  Dahl-Jenssen et al., Science, 282, 268 (1998).
>6.  Pfister, C. et al.,  The Holocene, 8, 535 (1998)
>7.  Jones, P.D. et al., Reviews of Geophysics, 37, 173 (1999).
>8.  Broecker, W.S., Science, 291, 1497 (2001).
>9.  K. Briffa et al., J. Geophys. Res., (2001)
>10.  Pollack, H.N. and S. Huang, Ann. Rev. Earth and Planet. Sci., 28, 339 
>(2000).
>
>
>Raymond S. Bradley
>Professor and Head of Department
>Department of Geosciences
>University of Massachusetts
>Amherst, MA 01003-5820
>
>Tel: 413-545-2120
>Fax: 413-545-1200
>Climate System Research Center: 413-545-0659
>Climate System Research Center Web Page: 
><http://www.geo.umass.edu/climate/climate.html>
>Paleoclimatology Book Web Site (1999): 
>http://www.geo.umass.edu/climate/paleo/html
>
>
>

_______________________________________________________________________
                      Professor Michael E. Mann
           Department of Environmental Sciences, Clark Hall
                       University of Virginia
                      Charlottesville, VA 22903
_______________________________________________________________________
e-mail: mann@virginia.edu   Phone: (804) 924-7770   FAX: (804) 982-2137
        http://www.evsc.virginia.edu/faculty/people/mann.shtml

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