Kategorie: News
Octopuses Instead of Mackerel: Ecosystems in Flux
July 2026 didn’t just set heat records on land: The highest surface temperatures ever recorded were also measured in the oceans surrounding Europe. A new report by the research initiative World Weather Attribution (WWA) shows that this record-breaking heat can largely be attributed to climate change—with significant consequences for marine food chains and ecosystems.
Along nearly all European coasts, water temperatures in July were significantly above the long-term average for the years 1990 to 2020. The western Mediterranean was particularly affected, where, according to EU data, temperatures in June were up to six degrees above normal in some areas, as were the Bay of Biscay and the coastal waters of the Iberian Peninsula. The WWA team led by Claire Bergin compared the temperature trends with climate models and determined the contribution of climate change: approximately two degrees of additional warming in the Mediterranean, 1.4 degrees in the Bay of Biscay and on the Iberian Peninsula, and 1.3 degrees around Ireland and the west coast of the United Kingdom.
The proportion of affected coastal regions has thus risen dramatically: 90 percent of the coasts along the Bay of Biscay and the Iberian Peninsula experienced heatwaves this year—without human-induced global warming, this figure would have been only about 40 percent, according to WWA calculations. Current international data also confirms this trend: According to the Copernicus Climate Change Service, the global sea surface temperature (excluding polar regions) reached a new record high for the month of July 2026, averaging 20.96 degrees, partly driven by a developing El Niño event in the Pacific.
Octopuses Instead of Mackerel
This development has noticeable consequences for marine life. Since 2025, fishermen in southwest England have reported a significant increase in the common octopus, a species normally found in the warmer waters of North Africa. At the same time, jellyfish populations are spreading along many coastlines—a trend fueled by the expansion of oxygen-depleted zones, which jellyfish, unlike many fish species, can tolerate well. This has serious consequences for dolphins: As their primary food source, mackerel, becomes increasingly scarce, they are reportedly feeding on jellyfish more and more often.
High water temperatures also contribute to the formation of severe storms—the WWA team cites the devastating floods in the Valencia region in the fall of 2024 as an example.
No Way Out Through Adaptation
“You can’t wriggle your way out of the climate crisis through adaptation,” warns climate researcher Friederike Otto of Imperial College London. Ecosystems are not only valuable for their own sake—entire economic sectors and millions of people depend on the oceans not continuing to warm as rapidly as they are now.
Further information:
World Weather Attribution
Copernicus Climate Change Service
Climate Change reaches new heights