Compiled 19 November, updated 20 November 2024
by Sara Gandolfi
Scientific report at the COP on the risks of the Mare Nostrum: it will rise up to a metre by the end of the century. Temperatures and floods on the rise
The Mediterranean Sea will erode up to 23 metres of coastline, putting beaches and cities at risk: the sea will rise by up to a metre by the end of the century
New SOS for the Mediterranean at the UN Climate Conference underway in Baku. On Monday, scientists from MedECC (Mediterranean Experts on Climate and environmental Change) published a new report on coastal risks in the Mare Nostrum. The outlook is nightmarish. In the region, the feared increase of 1.5°C compared to the pre-industrial era has already been reached in 2020 and by the end of the century it could even reach 2.9°C, in the worst case scenario. And the sea also has ‘the fever’: the increase in water temperature will range between 2.7 and 3.8°C by the end of the century.
What worries the experts most, however, is the speed at which the sea level is rising: about 2.8 mm per year, twice the 20th century average. The trend is expected to continue at a rate that will depend on future greenhouse gas emissions. By the end of the century, sea levels could rise by more than a metre, leading to increased coastal flooding. ‘Relative sea-level rise has already increased the frequency of flooding in the historic centre of Venice,’ the report confirms.
“Both beaches in the Northeast and small beaches in Southern Italy are at high risk of erosion and could disappear. The process is irreversible on a scale of centuries or millennia’. An ominous future, confirms Piero Lionello, professor of Oceanography and Atmospheric Sciences at the University of Salento and president of the MedCLIVAR network: ‘The sea level is a huge inertia. It cannot be stopped or countered quickly. Even if we were to reduce emissions quickly, it would continue to rise due to the thermal inertia of the oceans that continue to absorb heat, thus expanding,’ he explains. “There are scenarios, so-called ‘improbable but plausible’, that speak of a 15-metre rise by 2300”.
Equally alarming is the rate of coastal erosion, which will range between 17.5 and 23 metres by 2050 and even between 40 and 60 metres by the end of the century. The most dramatic consequences can be observed in river mouth areas, coastal stretches around ports and other coastal infrastructure. “In the absence of adequate adaptation and protection measures, beach erosion will increase in the coming decades, also increasing the risk of storm damage and reducing the extent of areas for tourism,” experts confirm.
Rainfall will decrease over most of the Mediterranean, but heavy rainfall will increase in some northern areas, thus also in Italy. The Mediterranean coast is among the regions of the world with the highest probability of flooding, and the frequency of extreme sea-level events, which occur once every 100 years, is likely to increase by at least 10 per cent by 2050 and 22 per cent by 2100.
A separate chapter concerns waste at sea. “The Mediterranean Sea is one of the most plastic-polluted areas in the world,” reads the report. “Floating plastic accumulates along its shores due to human activities and marine circulation. Plastic accounts for up to 82 per cent of observed litter, 95-100 per cent of total floating marine litter and over 50 per cent of seabed litter in the Mediterranean Sea.”
