Extreme ocean warming events, known as marine heatwaves (MHWs), have been observed to perturb significantly marine ecosystems and fisheries around the world.

The main objective of this study was to investigate the future evolution (until 2100) of sea surface temperature (SST) and marine heatwaves in the Mediterranean Sea, using the best dedicated multi-model ensemble available.

The obtained results show how in response to increasing greenhouse gas forcing, the events become stronger and more intense under RCP4.5 and RCP8.5 than RCP2.6 scenarios*. By 2100 and under RCP8.5, simulations project at least one long-lasting MHW every year, up to three months longer, about 4 times more intense and 42 times more severe that present-day events.

The authors state that MHW are expected to occur from June-October and to affect at peak the entire Mediterranean basin. Their evolution is found to occur mainly due to an increase in the mean SST, but increased daily SST variability also plays a noticeable role.

It is highlighted that until the mid-21st century, MHW characteristics rise independently of the choice of the emission scenario, the influence of which becomes more evident by the end of the period.

*A Representative Concentration Pathway (RCP) is a greenhouse gas concentration trajectory adopted by the IPCC in 2014. Four pathways (RCP2.6, RCP4.5, RCP6, RCP8.5) have been selected for climate modelling and research, which describe different climate futures, all of which considered possible depending on how much greenhouse gases are emitted in the years to come.

https://link.springer.com/article/10.1007/s00382-019-04661-z

Darmaraki et al. (2019) Future evolution of marine heatwaves in the Mediterranean Sea. Climate Dynamics 53:1371-1392.