by T Laepple and P Huybers, July 14, 2014 in PNAS

Determining magnitudes of sea surface temperature variability is important for attributing past and predicting future changes in climate, and generally requires the use of proxies to constrain multidecadal and longer timescales of variability. We report a multiproxy estimate of sea surface temperature variability that is consistent between proxy types and with instrumental estimates but strongly diverges from climate model simulations toward longer timescales. At millennial timescales, model−data discrepancies reach two orders of magnitude in the tropics, indicating substantial problems with models or proxies, or both, and highlighting a need to better determine the variability of sea surface temperatures.