The Mediterranean is a small sea. It covers less than one percent of the world's ocean surface. And yet, around its 46,000 kilometers of coastline, twenty-one countries and roughly 500 million people have, for at least 5,000 years, shared olive oil, vines, alphabets, gods, plagues, and grievances.
The geology is the start of the story. The Mediterranean is what is left of the ancient Tethys Ocean, mostly closed off by the collision of Africa and Eurasia. About six million years ago, in the Messinian Salinity Crisis, the whole basin dried up almost completely — a dry, salty, half-buried thing five kilometers below the surrounding land. Then the Atlantic broke through at Gibraltar in what may have been the largest flood in earth's history, refilling the basin in perhaps two years.
The sea that emerged is still unusual. It is warmer and saltier than the oceans that feed it. The eastern basin loses more water to evaporation than it gains from rivers, which means surface water flows in from the Atlantic and dense salty water flows out below. This circulation makes the Mediterranean a closed, slow system — beautiful, fragile, easy to break.
The Mediterranean is a sea you can change.
The marine biodiversity is extraordinary. About 17,000 species live here, almost a third of them endemic — found nowhere else. The fan mussel, the monk seal, the loggerhead turtle, the Posidonia seagrass, the red coral of the deep reefs. Some of these have already collapsed; some are clinging on. The Mediterranean monk seal is down to fewer than 700 individuals.
The threats are well-documented and accelerating. The Mediterranean is warming twenty percent faster than the global ocean average. Overfishing has emptied the basin of large predators. Tourism — the very thing that draws so much of the world to these coasts — produces enormous waste, often dumped directly into the sea. And the plastic: by some estimates, the Mediterranean now holds the highest concentration of microplastics of any sea on earth.
None of this is news, exactly. But the people of the basin, who have for so long taken the sea for granted as a fact of life, are beginning — slowly, region by region — to organize around it. Marine protected areas now cover about eight percent of the Mediterranean. Posidonia meadows are being mapped and protected. Fishing quotas are tightening. It is not enough. But it is something. The sea, after all, made us. It is past time we returned the favor.
