Relative sea level rise (RSLR) represents a major hazard for the Mediterranean coasts, which are already vulnerable to extreme events associated with storms surges and waves. Moreover, intense vertical land movements and complex marine circulation amplify the spatial variability of RSLR patterns in the area.

Assessing RSLR in the Mediterranean requires the collective effort of scientists from different fields, as well as a combination of appropriate modeling and monitoring tools. To this aim, more than 100 scientists from Italian universities and research centers met to consider the major challenges of RSLR research.

Topics of discussion covered five themes: (1) paleo–sea level, (2) the isostatic contribution to RSLR, (3) ocean circulation modeling, (4) geodynamical processes and RSLR, and (5) coastal area management.

The Mediterranean is an ideal location to study relative sea level rise because of its geological history and marine environment. Speakers presented various complementary approaches to the quantification and observation of the RSLR components. The meeting highlighted the fact that the Mediterranean is an ideal location to study RSLR because of the inherent diversity of its geological history and the complex features of its marine environment that make it a “miniature ocean.” It hosts sites of deep (western) and intermediate (eastern) water formation and internal, closed thermohaline cells. It is connected to the global ocean by the narrow and shallow Strait of Gibraltar, which determines the water mass exchange and the internal sea level through hydraulic controls.

During the meeting, attendees reviewed the role of the Strait of Gibraltar in regulating the hydraulic jump between the Mediterranean and the Atlantic Ocean and presented a new ocean model that explicitly resolves the hydraulic regime. The first results show that the hydraulic jump can strongly influence how sea level rise in the Atlantic is transmitted into the Mediterranean.

Participants proposed an ensemble-based approach to improve the accuracy of regional predictions of the glacial isostatic adjustment contribution to SLR. Moreover, they suggested that data from satellite-borne synthetic aperture radar systems should be used in conjunction with GPS data to narrow the range of ice mass loss estimates.

Data sharing is also crucial for the design of effective adaptation and/or impact mitigation measures. Workshop attendees underlined that public availability of the long-term tide gauge records, which have traditionally been carried out in the Mediterranean, would substantially improve satellite altimetry products in coastal areas and support the development of higher-resolution observational networks. Attendees agreed that an interdisciplinary database should be developed to improve scientific understanding of the phenomenon. Data sharing is also crucial for the design of effective adaptation and/or impact mitigation measures. We also identified key issues related to risk assessment methods, intervention design and implementation, and awareness raising. Details can be found on the workshop website, where a comprehensive synthesis of the meeting is provided. Ultimately, the workshop fostered a greater commitment from participants to collaborate on a challenge that requires a multidisciplinary approach.

We thank Paola Malanotte Rizzoli, Fabrizio Antonioli, Giorgio Spada, and Giovanna Pisacane for contributing to this report, as well as the Climate Modelling and Impacts Laboratory of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development for funding. The workshop was endorsed by the European Climate Research Alliance, the Climate Knowledge and Innovation Community, and the World Climate Research Programme.

—Gianmaria Sannino ([email protected]), Climate Modelling and Impacts Laboratory, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Rome, Italy