The Mediterranean Sea is saltier than the Atlantic Ocean, with salinity levels ranging from 38 to 39 grams of salt per kilogram of water, compared to 35 g/kg in the Atlantic, according to a study published in the geoscience journal Geophysical Research Letters. The research, carried out by oceanographers Elena Terzić and Ivica Vilibić from the Ruđer Bošković Institute in Croatia, analyzed temperature and salinity data collected in the Mediterranean between 1950 and 2025. They found that the sea is not only warming and becoming saltier, but these changes are accelerating and spreading deeper into the water column. Between 2000 and 2025, surface waters warmed on average by about 0.5 °C per decade, compared to less than 0.1 °C per decade during the second half of the 20th century. According to the Copernicus Ocean State Report, satellite data show that the Mediterranean's surface is warming two to three times faster than the world's oceans since 1982. The rate of warming has accelerated over the past seven decades of measurements, with some regions experiencing a warming of about 0.3 °C higher than the previous decade. Salinization is also increasing in the upper layers, especially in the Adriatic Sea and the Ionian Sea, with an increase of 0.1 g/kg of water compared to the previous decade. The analysis, which covers 75 years of data, remains valid even if the study begins one or two decades later. The researchers state that these changes are a response to climate change and not a temporary fluctuation. The process involves heat causing water to evaporate, which concentrates salt in the remaining volume. The Mediterranean loses more water through evaporation than it receives from precipitation and rivers. Some Atlantic water enters through the Strait of Gibraltar, but the salt stays in place, making the Mediterranean saltier than the Atlantic. Due to its small size and semi-enclosed nature, the Mediterranean reacts quickly to environmental changes. However, these changes are not limited to the surface. Warming and increased salinity have been observed down to 3000 meters depth, even though the average depth of the Mediterranean is 1500 meters. The researchers note that these changes affect the density of seawater, with temperature reducing density and salinity increasing it. These effects largely counterbalance each other, so that the density of Mediterranean waters has changed little. However, when cold and dry winter winds cool the surface, as is common in the Adriatic Sea, the water becomes dense enough to sink to greater depths. The formation of dense water continues, but the water that sinks is now warmer and saltier than before, as seen in the Adriatic. These physical changes are profoundly disrupting the Mediterranean ecosystem. As shown by another study published in the journal Frontiers in Ecology and the Environment, the rise in temperatures and salinity promotes the arrival of exotic species, while making it harder for local wildlife to adapt to these changing conditions. In a semi-enclosed sea, species find it difficult to migrate to other latitudes or longitudes. The depths, also affected by these variations, may no longer offer them a durable refuge. According to the researchers, the Mediterranean could provide an early indication of how quickly the properties of ocean basins can change under the effect of continuous climate forcing.