Effects of Marine Heatwaves (MHW) and Cold Spells (MCS) on the surface warming of the Mediterranean Sea from 1989 to 2018

Marine Heatwaves (MHW) and Cold Spells (MCS) in the Mediterranean Sea have been extracted from an SST dataset from which the annual warming trend had been removed. The number of events per year (max 6) and their intensity resulted stable, indicating that the increasing occurrence of actual MHW in the last decades is mainly due to the warming rate. The extent (daily mean around 10% of the basin surface) and duration of events (around 36 days per year) decreased at a rate of -15% and -13% per decade, respectively. The decrease, concentrated in summer for MCS and in winter for MHW, explains the difference between the summer and winter warming rates of the basin. The decrease of summer MCS and winter MHW is probably caused by the shorter duration of extreme atmospheric events.