Climate change is driving widespread marine heat waves across the globe

Aug. 10, 2026

The Pacific is experiencing a historic marine heat wave — but it’s far from alone. Every major ocean basin across the globe is currently experiencing unusually warm sea surface temperatures driven by climate change.

Pacific Ocean

• The Pacific continues to host the world’s largest marine heat wave, now covering 63 million square kilometers — about 17% of Earth's oceans — an area larger than North and South America combined. A strengthening El Niño is contributing to some of this warming in the eastern Pacific.

• Climate change is driving the vast majority of this event: 86% of the marine heat wave area would not have occurred without human-caused warming.

• Since January, approximately 94% of the Pacific has experienced marine heat wave conditions, with the most persistent hotspots in the North Pacific remaining in marine heat wave conditions for more than 180 consecutive days.

Mediterranean

• The Mediterranean marine heat wave has intensified following repeated heat waves over Europe, with 82.9% of the basin now experiencing marine heat wave conditions. About 85% of the current marine heat wave area is due to human-caused warming.

• Sea surface temperatures have climbed into the mid-80s to low 90s °F (29-32°C), while large areas of the western Mediterranean are running 9-10°F (5-6°C) above normal. 

• One hundred percent of the basin has experienced at least one day this year under marine heatwave conditions.

Atlantic Ocean

• Marine heat waves are less widespread across the Atlantic than in the Pacific or Mediterranean, with 23.3% of the basin currently affected. However, tropical sea surface temperatures largely remain in the upper 70s to upper 80s°F (24-32°C). Broad areas of the Atlantic are 2-5°F (1-3°C ) above normal compared to the 1991-2020 climatology.

• Climate change is driving nearly all of the existing marine heat wave area: 81% would not have occurred without human-caused warming.

Gulf of Mexico

• Marine heat waves encompass the southern Gulf of Mexico and the northwestern region of the Caribbean, as in some of the other basins, with 39.7% of the region currently experiencing marine heat wave conditions. Of the area experiencing marine heat wave conditions, however, 98% is attributable to climate change. 

• Sea surface temperatures are broadly in the 80s°F (27°C), with the hottest waters approaching 90°F (32°C) around Florida.

Indian Ocean

• Marine heat wave areas are more scattered in the Indian Ocean, affecting 33% of the basin. The most intense marine heat waves are concentrated in the southern Indian Ocean, and 95% of the current marine heat wave area would not have occurred without human-caused climate change.

For more information on the Climate Shift Index: Ocean, refer to the FAQs.