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Arctic sea-ice reduction and extreme climate events over the Mediterranean region

August 23, 2013

During the last decade, Arctic sea-ice cover has experienced an accelerated decline that has been suggested to drive the increased occurrence of extremely cold winter events over continental Europe. Observations and modeling studies seem to support the idea that Mediterranean climate is also changing. In this work we estimate potential effects on the Mediterranean basin, during the winter period, of Arctic sea-ice reduction. Two sets of simulations have been performed by prescribing different values of sea-ice concentrations (50% and 20%) on the Barents-Kara (BK) seas in the CAM3/NCAR atmospheric GCM, as representative of idealized sea-ice present and future conditions. Global model simulations have then been used to run RegCM4/ICTP regional model over central Europe and the Mediterranean domain. Simulations evidence a large scale atmospheric circulation response to sea ice reduction, resembling the negative phase of the Arctic Oscillation (AO) and characterized by a wave activity flux from the North Atlantic toward the Mediterranean basin, during winter months. We find an increase in the occurrence and intensity of extreme cold events, over continental Europe, and extreme precipitation events, over all the Mediterranean basin. In particular, simulations suggest an increased risk of winter flooding on southern Italy, Greece and Iberian peninsula.

 Grassi B, Redaelli G, Visconti G, in press. Arctic sea-ice reduction and extreme climate events over the Mediterranean region, Journal of Climate, 2013, doi: http://dx.doi.org/10.1175/JCLI-D-12-00697.1. Article (subscription required).

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