The world’s oceans are breaking heat records, and in some spots, temperatures have soared to unprecedented highs. Mercator Ocean’s latest report flags seven massive marine heatwaves currently raging across the globe.
Just off France, the Mediterranean is experiencing one of the most concerning events: water temperatures above 27 °C are rated “severe” (3 out of 4). While coastal French waters have cooled slightly, the eastern basin—toward Italy and Greece—grows hotter by the day.
In the Atlantic, a heatwave stretches from French and Spanish shores eastward. It’s easing now but still intense. Meanwhile, the U.S. East Coast—from Canada down to Florida—is sweltering, though signs of relief are emerging.
Up north, the Norwegian Sea is in the grips of a new heatwave, with surface temperatures hitting 20–23 °C. This zone now ranks “strong,” teetering on “severe.”
Areas currently affected by marine heatwaves. @ Mercator Ocean
Overheated Waters That Supercharge Hurricanes
Down in the Gulf—between southern Cuba and the Gulf of Mexico—sea surface temperatures exceed 30 °C, classified “severe.” As hurricane season kicks off, these scorching waters are prime fuel for storms. Any tropical system passing here faces a much higher chance of ballooning into a powerful hurricane.
Across Asia, two more heatwaves are in focus. One in the North Pacific—between the Sea of Japan and the Sea of Okhotsk—is intensifying and may soon hit “extreme” status above 30 °C. The other, in the Bay of Bengal, remains troubling but shows signs of easing.
In orange, areas of persistent heatwaves, in red areas of worsening heatwaves, and in blue areas of weakening heatwaves. @ Mercator Ocean
A New Normal for Marine Heatwaves
Year after year, these extreme water temperatures are becoming standard. The toll on marine life—already dire in the Mediterranean, Florida, and the North Atlantic—grows as ecosystems lack time to adapt.
Karine Durand
Specialist for extreme weather and environment
A specialist in extreme weather phenomena and environmental issues, this journalist and TV host has been explaining climate topics since 2009. With over 15 years of experience in both French and American media, she is also an international speaker.
Trained in communication and environmental sciences, primarily in the United States, she shares her passion for vast natural landscapes and the impacts of climate change through her work on biodiversity and land management.
