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The Role of Forcing and Internal Dynamics in explaining the 'Medieval Climate Anomaly'Proxy reconstructions suggest that peak global temperature during the past warm interval known as the Medieval Climate Anomaly (MCA, roughly 950-1250 AD) has been exceeded only during the most recent decades. To better understand the origin of this warm period, we use model simulations constrained by data assimilation establishing the spatial pattern of temperature changes that is most consistent with forcing estimates, model physics and the empirical information contained in paleoclimate proxy records. These numerical experiments demonstrate that the reconstructed spatial temperature pattern of the MCA can be explained by a simple thermodynamical response of the climate system to relatively weak changes in radiative forcing combined with a modification of the atmospheric circulation, displaying some similarities with the positive phase of the so-called Arctic Oscillation, and with northward shifts in the position of the Gulf Stream and Kuroshio currents. The mechanisms underlying the MCA are thus quite different from anthropogenic mechanisms responsible for modern global warming.
Document ID
20140001050
Document Type
Reprint (Version printed in journal)
Authors
Goossee, Hugues (Universite Catholique de Louvain Belgium)
Crespin, Elisabeth (Universite Catholique de Louvain Belgium)
Dubinkina, Svetlana (Universite Catholique de Louvain Belgium)
Loutre, Marie-France (Universite Catholique de Louvain Belgium)
Mann, Michael E. (Pennsylvania State Univ. University Park, PA, United States)
Renssen, Hans (Vrije Univ. Amsterdam, Netherlands)
Shindell, Drew (NASA Goddard Inst. for Space Studies New York, NY, United States)
Date Acquired
March 6, 2014
Publication Date
December 1, 2012
Publication Information
Publication: Climate Dynamics
Volume: 39
Issue: 12
Subject Category
Meteorology and Climatology
Report/Patent Number
GSFC-E-DAA-TN8964
Funding Number(s)
CONTRACT_GRANT: NSF ATM-0902133
WBS: WBS 509496.02.08.04
Distribution Limits
Public
Copyright
Public Use Permitted.

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