July 24, 2025 — Between 2014 and 2016, something very unsettling happened off the west coast of North America. For over two years, ocean waters from California to Alaska were unusually warm – 3.6°F to 10.8°F hotter than normal.
This wasn’t a one-off fluke or a seasonal shift. It was the longest and most intense marine heatwave ever recorded in the region.
The heat lingered, spreading across thousands of miles of ocean. This event reshaped life in the water in devastating ways.
Kelp forests collapsed and entire food chains were thrown off balance. Animals appeared in places they had never been spotted before, and many of them died.
An ongoing coastal crisis
The warm water pushed marine life out of their comfort zones – literally. According to newly published research, 240 species were found far beyond their usual ranges during the heatwave, many of them showing up more than 600 miles farther north than normal.
Northern right whale dolphins and small sea slugs like Placida cremoniana were spotted well outside their typical territory. For some species, the shift was temporary. For others, it hinted at a more permanent change.
As ocean waters heat up, many organisms are following the temperature they’re adapted to – heading toward cooler, northern waters in a bid to survive. But during the historic heatwave in the Pacific, some animals could not move fast enough.