The Mediterranean: Warmer, saltier, more acidic, and rising fast — report

Annual national monitoring report paints stark picture of sea under threat from climate change, with invasive species taking over and local ones disappearing

Driven by global climate change and human activity, the eastern Mediterranean Sea continues to warm, become saltier and more acidic, while rising faster than the global average, fundamentally altering the region’s ecology, according to the latest annual national monitoring report released on Wednesday.

The sea’s upper layer is warming by 0.05°C (0.09°F) annually, aligning with the UN’s Intergovernmental Panel on Climate Change’s projections.

From 1992 to 2024, the sea level rose by 15 centimeters (5.9 inches). At 4.7 millimeters (0.185 inches) per year, this is faster than the global average of 3.4 millimeters (0.134 inches) annually, heightening the risk of catastrophic coastal flooding during storms.

Seawater acidification is hindering species such as clams and corals from building their skeletons (which use calcium carbonate, an alkaline compound) and is turning the sea from a carbon store into a carbon source, further fueling the climate crisis and increasing the risks of extreme weather events.

Meanwhile, the Mediterranean’s native identity is being erased by a tropical influx. Alien species from the Red Sea now account for 68 percent of the fauna at 40-meter (131 feet) depths and 55% at 80 meters (262 feet) and above. Venomous lionfish and long-spined sea urchins (formerly exclusive to Eilat) are flourishing, while toxic algae create recurring nuisances on northern beaches.

For the second year running, local favorites such as red mullet and striped seabream have been notably absent from monitoring nets, likely unable to survive the warming waters.

Pollution casts a continuing shadow over Israel’s coast, the report found.

A staggering 75% of fish sampled in 2024 — the year covered by the report — exceeded the strict European mercury standard for consumption. These included white seabream and common soldierfish. While soil cleanup at the source, the former Electrochemical Industries site in Acre, is underway, groundwater restoration has yet to begin, meaning this contamination will likely persist for years.

Coastal streams still contain problematic concentrations of fertilizer and sewage, and some continue to suffer mass fish die-offs. This happens when fertilizer runoff triggers microscopic algae blooms that consume all available oxygen.

Meanwhile, arsenic levels have spiked at the Tel Aviv marina, HaYovel Port in southern Ashdod, and the Lachish Stream, which drains into the sea at Ashdod, for reasons the researchers cannot yet explain.

Simultaneously, silver pollution has been detected at Haifa’s port and the marinas in central Hadera and Herzliya.

Plastic remains the dominant pollutant on beaches. Nine out of the ten sea turtles examined had plastic in their systems, with over 100 individual items recovered from their digestive tracts.

Unlike the Mediterranean, where waste comprises up to 90% plastic bags and packaging, seabed waste in Eilat on the Red Sea in southern Israel consists primarily of boating and fishing gear, such as ropes, metal structures, and concrete sinkers.

Alon Zask, CEO of Israel Oceanographic and Limnological Research, which carried out the survey for the Energy and Environmental Protection ministries, said in a statement, “In an era of accelerated climate change and increasing human pressures, investment in continuous scientific monitoring is necessary for maintaining the resilience of the marine environment in Israel and the ability to deal with the challenges of the future.”