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. © 2012 Springer-Verlag.
Duke Scholars
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- Meteorology & Atmospheric Sciences
- 3708 Oceanography
- 3702 Climate change science
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- 0406 Physical Geography and Environmental Geoscience
- 0405 Oceanography
- 0401 Atmospheric Sciences
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Meteorology & Atmospheric Sciences
- 3708 Oceanography
- 3702 Climate change science
- 3701 Atmospheric sciences
- 0406 Physical Geography and Environmental Geoscience
- 0405 Oceanography
- 0401 Atmospheric Sciences