NOAA Warns Pacific Marine Heatwave Will Expand

A marine heatwave is a prolonged period of unusually warm ocean water, and the current Pacific event is exceptional both in scale and persistence. Scientists trace its ecological damage to weakened upwelling, which normally draws cold, nutrient-rich water toward the surface; when that pump falters, small fish and krill descend to deeper, cooler layers, forcing seabirds and other predators to work harder for food. Researchers compare today's conditions to "the Blob" of 2014–2018, which killed an estimated million seabirds and devastated salmon runs along the Pacific coast. Compounding the concern, the 2025–2026 heatwave overlaps with the formation of El Niño, the warm phase of a Pacific climate cycle that shifts weather patterns for half the planet. Forecasters now place the odds of a "strong" or "extreme" El Niño later this year at greater than two in three.

Ecological signals are already mounting. Marine ornithologists walking California beaches have catalogued dozens of dead seabirds in short stretches, while brown pelicans abandoned nests in Mexico and migrated north weeks early, apparently chasing prey. Subtropical species, including the first great white shark ever recorded in British Columbia waters, are shifting northward in search of food and cooler temperatures. On land, the linked atmospheric pattern has produced the warmest winter on record across the western United States and a March temperature spike of more than 30°F above normal in states such as Minnesota and Colorado. With record-low snowpack, intensifying drought, and El Niño looming, scientists warn the region is heading into a severe wildfire season and probable further losses for Pacific fisheries.