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Climate of the Past An interactive open-access journal of the European Geosciences Union

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Clim. Past, 7, 603-633, 2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research Article
16 Jun 2011
The early Eocene equable climate problem revisited
M. Huber1 and R. Caballero2
1Earth and Atmospheric Sciences Department, Purdue University, West Lafayette, Indiana, USA
2Department of Meteorology and Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden

Abstract. The early Eocene "equable climate problem", i.e. warm extratropical annual mean and above-freezing winter temperatures evidenced by proxy records, has remained as one of the great unsolved problems in paleoclimate. Recent progress in modeling and in paleoclimate proxy development provides an opportunity to revisit this problem to ascertain if the current generation of models can reproduce the past climate features without extensive modification. Here we have compiled early Eocene terrestrial temperature data and compared with climate model results using a consistent and rigorous methodology. We test the hypothesis that equable climates can be explained simply as a response to increased greenhouse gas forcing within the framework of the atmospheric component of the Community Climate System Model (version 3), a climate model in common use for predicting future climate change. We find that, with suitably large radiative forcing, the model and data are in general agreement for annual mean and cold month mean temperatures, and that the pattern of high latitude amplification recorded by proxies can be largely, but not perfectly, reproduced.

Citation: Huber, M. and Caballero, R.: The early Eocene equable climate problem revisited, Clim. Past, 7, 603-633, doi:10.5194/cp-7-603-2011, 2011.
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