Abstract
Marine heat waves (MHWs) occur when exceptionally warm ocean temperatures persist for several days or more. They cause mass-mortality events of wild and farmed marine species, severely affecting marine conservation efforts and aquatic food sector activities. In many parts of the global ocean, they are becoming more frequent, longer-lasting and more intense. In response, the CMCC has been applying its range of ocean models and forecasts to the tasks of understanding, tracking and predicting MHWs. This webinar will cover these activities and their potential benefits to society.

The webinar will begin with a focus on the recent summer MHW in the Mediterranean Sea, discussing our efforts to track its evolution and compare it to previous devastating MHWs (e.g., the summer of 2003). This will be followed by a description of the MHW characteristics and trends over the previous decades in the Mediterranean Sea, determined with 3D ocean reconstructions (reanalyses) and satellite data. Lastly, the capability of seasonal forecasts to predict MHWs several months in advance will be presented. Progress in monitoring subsurface MHWs and the role of climate change in MHW activity is also covered. Finally, the webinar will discuss the requirements of designing truly user-relevant monitoring and seasonal forecasting services.