Presentation to the
Subcommittee on Oversight and
Investigations of the
House Energy and Commerce
Committee.
Stephen McIntyre
Toronto Ontario
Washington DC, July 19, 2006.
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NAS Panel Recommendation on
Bristlecones Affects MBH
Figure 1. MBH99 reconstruction and estimate of
MBH99-type reconstruction without bristlecones.
20-year gaussian smooth.
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Up-to-date temperature data from Sierra
Nevadas shows no correlation of key MBH
PC indicator to temperature
Left - location of foxtail and bristlecone sites in the Sierra Nevada and
White Mountains, California. Sheep Mountain is denoted SHP. Right Black3 – annual mean of maximum and minimum temperatures (data,
Christy, pers. comm.); red – MBH98 NOAMER PC1.
MWP annual minimum temperature in the
California Sierra Nevadas estimated to be
+3.2 °C warmer than at present
Left: A dead trunk above current
treeline from a foxtail pine that lived
about 1000 years ago near Bighorn
Plateau in Sequoia National Park.
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PCs matter: a simple average of MBH
proxies does not yield a hockey stick
Top: average of MBH proxies. Bottom: result of MBH method.
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MBH Methods enhance weighting of
bristlecones – a proxy rejected by NAS
Top – Contribution (deg C) of 10 proxy groups (proxy type x continent e.g.
Asian tree rings; South American ice cores) to the MBH reconstruction,
with bristlecones/foxtails in red. The bristlecone contribution closely
matches the final MBH reconstruction.
Bottom6 – Same series in standard deviation units.
New research in late 2005 showed
that a bewildering variety of results
can be obtained from MBH proxies.
Source: Bürger and Cubasch SI Figure 1
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Moving On?: Precisely the same PC
series were used late last year in
Rutherford et al 2005
“Although 415 individual proxy series were
used, data reduction by using leading PCs of
tree-ring networks results in a smaller set of 112
indicators in the multiproxy–PC network
available back to 1820 (Fig. 1a), with a
decreasing number of indicators available
progressively further back in time. Twenty-two
of the indicators (representing 95 individual
proxy series) extend back to at least A.D.
1400.”
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MBH Results Failed Verification r2 Test
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Source: Wahl and Ammann 2006
Replication Problems Persist
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MBH source code provided to Committee does
not work with any data sets presently archived
and is inoperable.
code for some important steps, such as MBH99
confidence intervals or the application of
Preisendorfer’s Rule N, was not provided
Other authors are even worse: identity of sites
in Briffa et al 2001 (also used in Rutherford et al
2005) remain unreported and unavailable
You can make a difference …
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peer review at journals is very limited and is
insufficient due diligence for policy reliance;
IPCC does not carry out due diligence on articles;
to enable and facilitate independent testing,
paleoclimate research practices need to achieve
dramatically improved standards for archiving data
and code;
Because much of the work is funded by the U.S.
federal government, administrative changes at NSF
and DOE would have an immediate impact on
paleoclimate due diligence.
End of Presentation
Sir John Houghton at press conference releasing IPCC Third
Assessment Report.
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