Scientists tracking a major marine heatwave off the U.S. West Coast are sounding the alarm as new data shows it could have disastrous impacts on local ecosystems. 

According to a report from the Guardian, the marine heatwave, which spans thousands of miles across the Pacific, is now expected to intensify, and it could collide with El Niño conditions to create a punishing summer on land and at sea.

New projections from the National Oceanic and Atmospheric Administration show that the massive marine heat wave off the coast of California is likely to intensify in the coming months after lingering in the region since reaching its largest extent in September 2025. The warm-water zone extends from waters near Hawaii up to British Columbia and down toward Mexico, disrupting an enormous swath of ocean habitat.

Scientists had hoped in early spring that the system might fade. Instead, recent ocean data has forced many researchers to rethink how quickly the atmosphere and ocean are responding in a warming world.

University of Arizona scientist Kim Wood summed up the mood online in a post on BlueSky: "I'm out of superlatives."

Experts say the warm Pacific has already helped fuel extreme temperatures across the U.S., including a startling March heat wave that pushed some places more than 30 degrees Fahrenheit above normal.

Berkeley Earth's Robert Rohde said on social media that the event "would have been impossible without a boost from climate change."

The heatwave could have sweeping effects on daily life in the West. Warmer ocean water can feed hotter air, worsen drought, reduce mountain snowpack, and raise the risk of dry thunderstorms that ignite wildfires instead of delivering meaningful rain.

Water managers are already dealing with alarmingly low snow levels in parts of California, Oregon, Colorado, Utah, Wyoming, and New Mexico.

Marine ecosystems are also flashing warning signs. Researchers are watching for shifts in salmon, krill, seabirds, seals, and whales, with echoes of the 2014-2016 "Blob" heatwave that devastated food webs.

Scientists have already noted unusual behavior, including pelicans leaving nesting grounds early and subtropical species moving farther north.

NOAA scientists are ramping up ecosystem monitoring this summer, including offshore surveys using advanced sonar to measure krill, plankton, and other building blocks of the Pacific food chain.

Researchers say those observations will be crucial for understanding whether this year's event will mirror the ecological damage seen a decade ago.

Experts are preparing for the possibility that El Niño strengthens later this year. Forecasters say the odds of a strong or extreme event are now better than two in three, the Guardian noted, which could further reshape weather patterns across the Pacific and beyond.

"This is going to be a big hit on our fisheries for a couple of years," Larry O'Neill, an Oregon State University climatologist, told the outlet.

Elizabeth Phillips, a research scientist with NOAA Fisheries, added, "The last six months have been really concerning. As a scientist, I'm really curious to know what the ecosystem impacts are going to be."

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