date: Sun, 27 Feb 2005 12:14:17 -0500
from: "Shaopeng Huang" <REDACTED>
subject: borehole-based climate reconstruction

Dear IPCC AR4 Paleoclimate Chapter lead authors,

Attacked please find a reprint of my letter published in Nature this week (Feb. 24) and the
email exchange I had with earlier regarding some borehole-based
reconstructions. I thought you might be interested in reading them.


Shaopeng Huang

Attachment Converted: "c:eudoraattachNature5224.pdf"
From: "Shaopeng Huang"
Subject: how small is small and how big is big
Date: Mon, 24 Jan 2005 18:31:14 -0500

Thank you for responding to my concern about your December 4 posting. You
stated in your added comment that the two borehole curves of your Figure 1
suffer from a "small error in the areal weighting normalization". But how
small is this "small error"? According to Rutherford and Mann (2004), it is
a factor of 1.47. In comparison, how big is the arithmetic mean different
from "appropriately" 5-deg by 5-deg weighted mean? According to Huang (2004)
based on the existing borehole database, it is a factor of 1.01.

It is also confusing that you cited Briffa and Osborn (2002) and Mann et al.
(2003) both as "appropriately areally-averaged" reconstruction of borehole
data. Briffa and Osborn (2002) employed a 10-deg by 10-deg averaging scheme
(Osborn, per. comm.) while Mann et al. (2003) and Rutherford and Mann (2004)
took a 5-deg by 5-deg area weighting approach. They are different. For your
information, Pollack and Smerdon (2004) and Huang (2004) show how different
averaging methods would lead to different mean values. Huang (2004) further
presents the latest borehole-based NH reconstruction with complementary
information from the 20th century SAT record and the multi-proxy model of
Mann et al. (1999).

-----Original Message-----
Sent: Thursday, January 13, 2005 1:02 PM
To: Shaopeng Huang
Subject: Re: Comment on Temperature Variations in Past Centuries and the
so-called 'Hockey Stick'

Thank you for pointing this out. We have placed a comment in the caption
to the figure correcting this oversight, and directing readers to the
corrected figures in the Rutherford and Mann (2004) or Jones and Mann
(2004) papers.

> I am sadly disappointed by your misrepresentation of ground surface
> temperature history reconstruction. I wonder why you would use an outdated
> illustration (Figure 1) in which borehole-based reconstruction is
> misrepresented by the erroneous Mann et al. (J. Geophys. Res., 2003),
> rather
> than by the original reconstruction by Huang et al. (Nature, 2000), or the
> result of Pollack and Smerdon (J. Geophys. Res., 2004) which first pointed
> out a serious error of the Mann et al. (2003) reconstruction, or the
> result
> of Rutherford and Mann (J. Geophys. Res., 2004) which acknowledged the
> error
> and offered a substantial correction to the shown representation, or the
> latest integrated reconstruction by Huang (Geophys. Res. Lett., 2004).
> Advocating a piece of work of known error is not in the best interest of
> climate research community in general and RealClimate in particular.
> Shaopeng Huang
> University of Michigan