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GEOPHYSICAL RESEARCH LETTERS,
VOL. 32,
L23711,
doi:10.1029/2005GL024155,
2005
Are multiproxy climate reconstructions robust?
Gerd Bürger
Institut für Meteorologie, Freie Universität Berlin, Berlin, Germany
Ulrich Cubasch
Institut für Meteorologie, Freie Universität Berlin, Berlin, Germany
Abstract
64 climate reconstructions, based on regression of temperature fields on multi-proxies and mutually distinguished by at least
one of six standard criteria, cover an entire spread of millennial histories. No single criterion is accountable for the spread,
which appears to depend on a complicated interplay of the criteria. The uncertainty is traced back to the fact that regression
is applied here in an extrapolative manner, with millennial proxy variations exceeding the standard calibration scale by a
factor of 5 and more. Even if linearity still holds for that larger domain the model error propagates in a way that is proportional
to both the estimation error and the proxy variations, and is thus extrapolated accordingly. This is particularly critical
for the parameter-loaded multiproxy methods. Without a model error estimate and without techniques to keep it small, it is
not clear how these methods can be salvaged to become robust.
Received 30
July
2005;
accepted 1
November
2005;
published 14
December
2005.
Index Terms: 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3344 Atmospheric Processes: Paleoclimatology (0473, 4900).
Read Full Article (file size: 773524 bytes) Cited by
Citation: Bürger, G., and U. Cubasch
(2005),
Are multiproxy climate reconstructions robust?,
Geophys. Res. Lett.,
32,
L23711,
doi:10.1029/2005GL024155.
Copyright 2005 by the American Geophysical Union.
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