High regional climate sensitivity over continental China inferred from glacial--recent changes in temperature and the hydrologic cycle

Eagle, R. A., C. Risi, J. L. Mitchell, J. M. Eiler, U. Seibt, J. D. Neelin, G. Li, A. K. Tripati*, 2012:
Proc. Nat. Acd. Sci., 110 (22) 8813-8818, doi:10.1073/pnas.1213366110.
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Abstract. The East Asian monsoon is one of Earth's most significant climatic phenomena, and numerous paleoclimate archives have revealed that it exhibits variations on orbital and suborbital time scales. Quantitative constraints on the climate changes associated with these past variations are limited, yet are needed to constrain sensitivity of the region to changes in greenhouse gas levels. Here, we show central China is a region that experienced a much larger temperature change since the Last Glacial Maximum than typically simulated by climate models. We applied clumped isotope thermometry to carbonates from the central Chinese Loess Plateau to reconstruct temperature and water isotope shifts from the Last Glacial Maximum to present. We find a summertime temperature change of 6-7 °C that is reproduced by climate model simulations presented here. Proxy data reveal evidence for a shift to lighter isotopic composition of meteoric waters in glacial times, which is also captured by our model. Analysis of model outputs suggests that glacial cooling over continental China is significantly amplified by the influence of stationary waves, which, in turn, are enhanced by continental ice sheets. These results not only support high regional climate sensitivity in Central China but highlight the fundamental role of planetary-scale atmospheric dynamics in the sensitivity of regional climates to continental glaciation, changing greenhouse gas levels, and insolation.

Citation. Eagle, R. A., C. Risi, J. L. Mitchell, J. M. Eiler, U. Seibt, J. D. Neelin, G. Li, A. K. Tripati, 2012: High regional climate sensitivity over continental China inferred from glacial--recent changes in temperature and the hydrologic cycle. Proc. Nat. Acd. Sci., 110 (22) 8813-8818, doi:10.1073/pnas.1213366110.

Acknowledgments. We thank D. Battisti, M. Berkelhammer, J.-E. Lee, A. LeGrande, F. Pausata, and C. Yapp for valuable discussions during the formulation of this paper. We thank J. Canet, M. Enriquez, and J. Meyerson (University of California, Los Angeles) for the extraction of Climate Station and PMIP2 model data, and D. Pittman for supervising the data extraction. We acknowledge the international modeling groups participating in the PMIP2 for providing their results for analysis, and the Laboratoire des Sciences du Climat et l'Environnement (LSCE) for collecting and archiving the model results. We also thank N. Thiagarajan for provision of a compilation of speleothem isotope data. This work was funded by National Science Foundation (NSF) Grant EAR-0949191 (to A.K.T.) as well as by NSF Grants EAR-0909194 and EAR-1024929 (to J.M.E.). J.D.N. was supported by NSF Grant AGS-1102838. This work was also supported by National Aeronautics and Space Administration Grant 07-NEWS07-0020 (to D. Noone, which supported C.R.).