How Climate Change is Endangering the Mediterranean Sea: What You Need to Know

A recent study by the GEOMAR Helmholtz Centre for Ocean Research Kiel dives into how climate change impacts marine and coastal ecosystems in the Mediterranean Sea. This region is warming faster than many parts of the world, with temperatures currently reaching 28°C. July 2025 marked the warmest month on record there, averaging 26.9°C, according to the Copernicus Earth Observation Service.

Dr. Abed El Rahman Hassoun, a biogeochemical oceanographer, points out that the rising temperatures pose serious risks. “These aren’t just future problems; we see real damages happening now,” he explains. Climate change, alongside issues like overfishing and pollution, threatens the entire ecosystem.

Working with Professor Meryem Mojtahid from the University of Angers, Hassoun analyzed 131 studies on the Mediterranean. Their findings led to a “burning ember” diagram—a risk assessment tool from the IPCC—to illustrate these threats. The Mediterranean, unlike the open ocean, is particularly vulnerable due to its enclosed nature, making it a “hotspot of climate change.”

From 1982 to 2019, surface temperatures rose by 1.3°C in the Mediterranean, compared to a global average of just 0.6°C. This rapid change makes the region an early warning system for climate impacts. What happens here often foreshadows broader changes in the world’s oceans.

The study suggested two different scenarios for future warming. In a medium emissions scenario (RCP 4.5), we could see an increase of 0.6 to 1.3°C by 2050. In a high emissions scenario (RCP 8.5), warming could reach as much as 3.8°C. Such drastic changes would likely lead to significant disruptions, including loss of vital ecosystems like seagrass meadows and coral reefs.

Hassoun emphasizes that political decisions today matter. “Every tenth of a degree counts,” he stresses. Even with moderate climate action, some consequences are inevitable. The goal must be to limit the impacts as much as possible.

The researchers explored various marine ecosystems, including fish populations and macroalgae. Increases in temperature and acidity are altering these communities. For instance, seagrass like Posidonia oceanica could vanish by 2100. Fish stocks may decline by up to 40%, shifting north and making room for invasive species like the lionfish.

Coral reefs, while generally more resilient, still face risks if temperatures rise by 3.1°C. Marine mammals and sea turtles might experience shifts in feeding and migration patterns. Rising sea levels threaten nesting sites for sea turtles, with over 60% potentially lost.

Despite the urgency, research gaps remain. Many studies on deep-sea habitats and other ecosystems are limited, especially in the southern and eastern Mediterranean. As scientists lack comprehensive data on multiple stressors like pollution and invasive species, more interdisciplinary research and monitoring are necessary.

The Mediterranean serves as a crucial reminder of how interconnected our ecosystems are and the pressing need for action. The choices made today will shape the future of not just this region, but the world’s oceans.

For further insights, you can explore the IPCC’s latest climate reports which detail various climate scenarios and their potential impacts on ecosystems worldwide.

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