Reconstructing past climate from noisy data.
Empirical reconstructions of the Northern Hemisphere (NH) temperature in the past millennium based on multiproxy records depict small-amplitude variations followed by a clear warming trend in the past two centuries. We use a coupled atmosphere-ocean model simulation of the past 1000 years as a surrogate climate to test the skill of these methods, particularly at multidecadal and centennial time scales. Idealized proxy records are represented by simulated grid-point temperature, degraded with statistical noise. The centennial variability of the NH temperature is underestimated by the regression-based methods applied here, suggesting that past variations may have been at least a factor of 2 larger than indicated by empirical reconstructions.
Institute for Coastal Research, GKSS Research Centre, Geesthacht 21502, Germany. storch@gkss.de
Hans
H
von Storch
Eduardo
E
Zorita
Julie M
JM
Jones
Yegor
Y
Dimitriev
Fidel
F
González-Rouco
Simon F B
SF
Tett