Comment on "Reconstructing Past Climate from Noisy Data"
Eugene R. Wahl1*,
David M. Ritson2 and
Caspar M. Ammann3
1 Environmental Studies and Geology Division, Science Center, Alfred University, Alfred, NY 14802, USA.
2 Physics Department, Stanford University, Stanford, CA 94305, USA.
3 Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO 80307, USA.
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Fig. 1. MBH and VSO4 climate reconstructions. (A) Original MBH (2) Northern Hemisphere surface temperature instrumental data and reconstruction over calibration (1902 to 1980) and verification (1854 to 1901, shaded) periods. Curves show moving averages, smoothed with a 21-year Gaussian filter (without end extrapolations). No offset exists between the instrumental and reconstructed series during the calibration period, and the reconstructed mean in the verification period (using the spatially more restricted verification grid) misses the instrumental target by only 0.037° (annual, unsmoothed data) (10). (B) Like (A), but for von Storch et al. (1) simulated MBH-style reconstructions (using pseudoproxies from ECHO-G model output with no noise—i.e., perfect—and 75% white noise added) compared with actual ECHO-G Northern Hemisphere surface temperatures over 1854 to 1980. The large offsets in the calibration and verification (shaded) periods are highlighted by arrows.
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