HR: 17:45h
AN: PP44A-07 INVITED    [Abstracts]
TI: Simulation of Arctic climate response to high- and low- latitude volcanic eruptions during the late 13th Century: Possible early onset of the Little Ice Age
AU: * Schneider, D P
EM: dschneid@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, United States
AU: Ammann, C M
EM: ammann@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, United States
AU: Otto-Bliesner, B M
EM: ottobli@ucar.edu
AF: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, United States
AB: In some parts of the Northern Hemisphere high latitudes, the transition from relatively warm climatic conditions during medieval time (sometimes termed "Medieval Warm Period" or "Medieval Climatic Anomaly") to the first episode of clearly cooler conditions associated with the "Little Ice Age" occurred in the second half of the 13th Century. As part of a synthesis project of the last 2000 years of Arctic climate variability derived from high- resolution lake records, we are evaluating the synchroneity of this important climatic transition across the northern American to northern European sector and studying potential mechanisms responsible for the change. One strong candidate is volcanic forcing. Several of the recent estimates of the temporal evolution of volcanic forcing suggest that the late 13th Century was among the most volcanically perturbed half-century of the last 2000 years. Here, we discuss simulations of such volcanic perturbations for the 13th Century performed with a moderate resolution version of the Community Climate System Model version 3 (a fully coupled atmosphere, ocean, land surface and sea-ice model). Because none of the 13th century eruptions have been clearly attributed to specific volcanoes, we performed two sets of ensemble simulations, one assuming a sequence of tropical eruptions as the source of the volcanic sulfate spikes in the polar ice records, and one assuming multiple high- latitude eruptions. We address the spatial-temporal patterns of Northern Hemisphere climate response, including the contribution of both the direct radiative perturbation and dynamical responses such as changes in the Northern Annular Mode and how they contrast between the experiments with different source of volcanic perturbations.
DE: 1620 Climate dynamics (0429, 3309)
DE: 1626 Global climate models (3337, 4928)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting