The growing risks associated with warming and its high vulnerability mean that the Mediterranean region is classified as especially sensitive to the climate crisis. Its temperatures are 1.5ºC higher than the pre-industrial level and since the 1980s they have exceeded the planetary average. And a 12% reduction in rainfall is expected if the warming reaches 3ºC.
Surface waters have warmed between 0.29ºC and 0.44ºC per decade in 40 years and their accelerated rise (as a result of thaws) has already reached 3.3 mm per year, so they can reach one meter at the end of century in the worst case scenario, and intensify coastal erosion.
The impacts of extreme weather in this region make up an extensive chapter in the sixth report on climate change by the UN expert group (IPCC, 2022).
Its marine ecosystems are already undergoing structural changes, including the expansion of tropical species from the Red Sea, and sea acidification (a reaction of the waters by absorbing CO2 from the atmosphere) threatens the meadows of underwater plants and calcareous organisms.
In the open sea, the abundance of some small and medium-sized fish will decline by up to a third by the end of the century, and high temperatures will continue to undermine the metabolism of some coral species, the report says.
And it is also considered probable that marine heat waves will continue, which will increase the episodes of mass mortality of species on the seabed, such as corals, sponges, bivalves and other immobile beings anchored on the sea floor. The fear is "an abrupt collapse of species typical of the Mediterranean."
The problem here is that the climate crisis interacts with other factors, such as plastic pollution and residual fertilizer discharges from the agricultural and livestock industries, which eutrophicate and suffocate aquatic life, as has been seen in the Mar Menor.
And all this within a framework that requires strategies for good water management, since the volumes of the rivers that flow in the basins are dwindling and the underground reserves are largely overexploited.
Therefore, the challenges of adaptation are going to be enormous. Suffice it to say that the fisheries, which reached a value of 3.4 billion dollars in 2017, or the fate of the tourism industry, vulnerable to climate change, are at stake.
But, at the same time, it will be necessary to face the defense of the coast and its low areas. An example: in the Nile delta between 1,500 and 2,600 km2 of land and 6.3 million people will be exposed to flooding by the end of the century, with a sea rise of 0.75 meters and additional subsidence of the delta. 0.25m.
The necessary answers are policies and agreements with criteria of rational prosperity to protect a sea that unites three continents and centuries of civilizations. Of 49 UNESCO World Heritage sites in low-lying coastal areas, 37 are at risk of 100-year flooding and 42 of them are currently suffering from coastal erosion. Saving the identity of its banks is also a moral imperative.
