El Niño is a climate pattern centered along the equator in the Pacific Ocean that typically peaks around December. The phenomenon was named by Peruvian fishermen who noticed the disappearance of anchovies – their most important coastal fishery – around Christmastime in some years, and called those events the El Niño de Navidad (translates to Christ Child). We now understand that an El Niño can have serious consequences across the globe. Some places get dry and warm, while others get heavy rain and flooding. In the Pacific, El Niño conditions are typified by warmer than normal surface ocean waters, and a lowering of coastal ocean productivity (less phytoplankton and other base of the food chain organisms) with disastrous results to those at the top of the food chain, like seabirds, marine mammals, and humans.
NOAA (the National Oceanic and Atmospheric Administration) tracks a set of climate measures across the Pacific Ocean. Known as the Niño indices, these satellite-based measures register the difference between current sea surface temperatures and long-term (30-year) averages over several longitudinal slices (pole to pole) of the equatorial ocean. Typical of a brewing El Niño, this year is warmer than normal: about half a degree (Celsius) towards Indonesia (western Pacific) and a whopping 2.7o in the eastern Pacific (the slice bordering South America).
Along the continental border of the Americas, it’s been warmer than normal since January, with the departure from baseline growing monthly. The climate models that NOAA also tracks have “very high confidence” that we’ll have a full blown El Niño starting in the fall and moving through the winter into spring. What’s high confidence? NOAA reports that there is an “81% chance of a very strong El Niño” and a “97% chance it will last through early spring 2027.” More than that, this one is forecast to be a doozy, ranking amongst the largest El Niño events since 1950.
Here’s a colorized map of world sea surface temperature, centered on the Pacific Ocean. Dark red is 4-5oC above normal, dark blue is 2-3oC below normal. There’s a lot going on, but one of the most noticeable things is the tongue of warm water extending from Ecuador out across the Pacific along the equator, and smearing north and mostly south along the coastline. That’s the El Niño signal, and it’s forecast to do three things over the next 6+ months: become stronger (even darker red), extend to the Indo-west Pacific, and radiate north and south to cover the entire coastline of North and South America. In the COASST region, from northern California up into Alaska, there’s still some blue on the map as of August 2026; it’s not all yellow-orange-red. That cold water is created by spring-summer seasonal upwelling pulling deep, cold water to the surface as the wind and Earth’s rotation move surface waters offshore. But the normal fall shift to a more downwelling condition (surface waters move towards the shore) is about to break up that pattern. Soon, warmer water from offshore, and/or from the south, will flood into our coastal environment. Because a full-blown El Niño suppresses the strength of coastal upwelling, there’s a good chance that the following spring transition back to cold, nutrient-rich upwelled waters willnot fully materialize, leaving spring breeders at the top of the foodweb – like seabirds – with a food desert.
What should COASSTers expect as we head into the post-breeding “high season”? History suggests the news isn’t good. COASST and beached bird program partners BeachCOMBERS (Monterey Bay area) and Beach Watch (San Francisco North) collaborated on an analysis of 30 years of marine bird beaching rates along the Lower 48 coastline as a function of sea surface temperature in that region. What we found is that when the coastal sea surface temperature exceeds 1oC for 6 months or more, the chance of a mass mortality event is 100%, and is followed by a second event within the next year (the red humps in the figure below). Yikes! A 1-2 punch to coastal seabird populations.
In the 2015-2016 event (variously referred to as an El Niño, the North Pacific marine heatwave, and/or “The Blob”), Alaska Maritime National Wildlife Refuge researchers discovered that the ensuing common murre die-off topped 4 million adults (half of the Alaskan population!). Decimated colonies have yet to fully recover. A large, long-lived El Niño will certainly take a toll.
We’ve had reports for a few months of elevated beaching rates to the south of COASST’s range, in southern California. Reports from coastal Ecuador are also becoming alarming, with hundreds of carcasses washing in. And in the past weeks, reports from the Oregon coastline indicate that murres – both fledglings and adults – are washing in at higher than normal numbers. The signs of things to come have started.
Mass mortality events are not fun, COASSTers know this. In fact, they can be heart-breaking. Sure, death is part of the life of the ecosystem, but processing tens (or occasionally hundreds!) of carcasses is mind-numbing, soul-sucking, back-breaking work. As we head into fall, it pays to be prepared, especially if your beach is a “birdy” one:
- Read the wreck protocol in the COASST protocol (Pages 4BB 56 –59).
- Take extra supplies – tags and datasheets – (Email to let us know if you need more supplies mailed to you!)
- Plan ahead for more time on the beach
- Take extra team members – newbies can help search, hand out tags, and write information onto datasheets
- Remember to take time to celebrate and reaffirm the good work your and your team are doing.
Finally, center in the science – frontline work documenting the impacts of climate extremes like El Niño is making a difference. Coastal resource managers can’t move to protect species without knowledge of the size and scope of marine bird impacts. Science can’t tell the full story without COASST data and COASST data cannot exist without YOU!