Recently, you may have heard about something called “El Niño.” But what exactly is El Niño and its sibling “La Niña”? Why do these terms seem to emerge from the depths of the scientific community and drop into popular vocabulary every few years? And how are they connected to extreme weather and our ocean?
What Are El Niño and La Niña?
El Niño and La Niña are part of a natural climate pattern in the tropical Pacific called the El Niño-Southern Oscillation, or ENSO. These two phases are different sides of the same coin, creating equally extreme shifts in temperature and air pressure.
El Niño occurs when surface water in the equatorial Pacific becomes warmer than average and easterly winds weaken. La Niña is the opposite: cooler-than-normal sea surface temperatures and stronger easterly winds. ENSO cycles can last up to seven years. El Niño and La Niña significantly impact weather patterns in all corners of the globe, often leading to more extreme weather, storm frequency and intensity.
A strong El Niño can cause flooding in some regions and drought, heat waves and wildfires in others. It often causes crop losses, coral bleaching and marine die-offs due to unusually warm ocean temperatures. El Niño tends to suppress Atlantic hurricane activity, though it increases the risk of heavy precipitation and harm to fisheries elsewhere. In the Northern Hemisphere, El Niño typically builds between March and June, peaks in December, and weakens by February.
La Niña, by contrast, often fuels an active Atlantic hurricane season and increases tornado frequency across the southern United States. Like El Niño, it builds in spring and peaks around December.
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Predicting ENSO
In 1923, the physicist Sir Gilbert Walker discovered the “Southern Oscillation,” or large-scale changes in sea level pressure across the tropical Pacific. However, it wasn’t until the late 1960s that the metorologist Jacob Bjerknes found that the changes in the ocean and the atmosphere were connected, and the hybrid term “ENSO” was born. In 1974, researchers at Oregon State University attempted to predict ENSO for the first time.
Modeling has greatly advanced since the early days. Today, scientists at the National Oceanic and Atmospheric Administration (NOAA) issue regular predictions about ENSO, which are now more accurate than ever.
NOAA gives a one-in-four chance that an El Niño could reach “very strong” intensity later in 2026, qualifying it as a “super El Niño.” This threshold has been crossed only a handful of times in recorded history, each triggering droughts, floods and record temperatures across multiple continents. NOAA’s data and models deliver life-saving early warning forecasts, like that of the predicted super El Niño, which allow communities to better prepare for and respond to extreme weather events.
Take Action
Every American, regardless of where they live, depends on NOAA’s scientists and professionals, whose work spans from the ocean floor to the far reaches of space. Unfortunately, NOAA is under threat. The Trump administration has proposed billions of dollars in cuts to the agency, which could weaken weather forecasting, disrupt fisheries management and stall critical ocean research, putting American lives and global scientific leadership at risk.
Ocean Conservancy is committed to working with NOAA to keep the public informed on climate and ocean science. We all benefit from a healthier ocean, and investing in research is the most effective way to restore ocean health and reduce the impact of severe weather events caused by El Niño and La Niña. Our ocean is not partisan, and protecting it requires all hands on deck and all sides of the aisle. Now, it’s more important than ever to demand that members of Congress prioritize our ocean. Add your name now.
The post Do You Know the Difference Between El Niño and La Niña? appeared first on Ocean Conservancy.
Ocean Acidification
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026. Click here for the full story.
Dr Heidarzadeh’s TV interview with SkyNews on the massive M7.7 Panama earthquake on 9 October 2026
Our ocean is an incredibly vast and mysterious place. And there is no place where that is more evident than the deepest ocean area in the world: the legendary Mariana Trench. Located east of the Philippines, the Mariana Trench lies in the Mariana Archipelago in the western portion of the North Pacific. The greater area of the Mariana Trench Marine National Monument is made up of more than 95,000 square miles of ocean. Beneath these waters lie incredibly complex aggregations of submerged islands and volcanoes … and of course, an astoundingly massive trench.
Dive in with us to have your biggest questions answered about the famed Mariana Trench.
How deep is the Mariana Trench?
The deepest part of the Mariana Trench, known as Challenger Deep, is almost 36,000 feet below the ocean’s surface. For context, Mount Everest is about 29,000 feet above sea level, so the Mariana Trench is about 7,000 feet deeper than Mount Everest is tall. For one more comparison, the RMS Titanic lies at a depth of about 12,500 feet below sea level. The Challenger Deep is in waters nearly three times deeper than this ship’s final resting place.
Due to its enormous size, the Mariana Trench has at times been affectionately nicknamed the Grand Canyon of the ocean. This is certainly a picturesque image, but don’t let the mammoth size of this U.S. national terrestrial park fool you into thinking the Mariana Trench matches its size. The trench’s footprint is estimated to be 120 times larger than the Grand Canyon’s, and to reach the bottom of Challenger Deep, you’d need to descend through almost six Grand Canyons stacked on top of each other before you’d reach the seafloor.
Oh … and did we mention it’s five times wider than it is deep? It’s about 43 miles wide!
What is Challenger Deep, and how long would it take to reach it?
Challenger Deep is the deepest point of the Mariana Trench. Fewer than 30 people have ever journeyed to this area. The trek below the surface is long, dark and time-consuming, and it’s not an expedition considered lightly by scientists and explorers.
The first people to descend into the depths of this area in 1960 were oceanographers Jacques Piccard and Don Walsh, and it took them close to five hours to reach Challenger Deep. Since then, more advanced submersibles have been created, but it still takes two to four hours for modern vessels to reach such depths. For example, explorer and filmmaker James Cameron reached the seafloor in a little more than 2.5 hours in the first documented solo submarine dive to the area, and it took oceanographer Dr. Dawn Wright about four hours in 2022. It is crucial that these submersibles descend slowly and steadily beneath the surface, as the immense water pressure compounds with every mile a submersible descends. Speaking of pressure …
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