Climate change

The effects of ocean warming on marine biodiversity conservation is a main concern in many coastal areas. There is still considerable uncertainty about the magnitude of the actual warming, particularly in coastal waters. However, in the Mediterranean region, all the models have shown higher than average warming. They have indicated an increase in mean temperature and in climate variability, including current and future extreme events such as heat waves. The analysis of the longest temperature series available for the NW Mediterranean showed a significant regional warming trend over the last 30-years of about +1°C, which was linked to an increase in the number of warm anomalies.

In the NW Mediterranean, changes in species distribution and mass mortality events in recent decades have been related to the warming trend observed in this area. In particular, two recent large scale (>1000 km of coastline) mass mortality events (MME) were observed during the summers of 1999 and 2003, in association with two positive thermal anomalies. These large scale events affected over 30 species of benthic invertebrates, particularly gorgonians and sponges. As a result of climate change, the coastal ecosystems could suffer serious changes in their structure and dynamics.