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Something unusual is unfolding in the largest and deepest ocean on Earth this fall. Scientists at the National Aeronautics and Space Administration (NASA) are monitoring a possibly historic climate pattern known as El Niño that could be “rarer than a solar eclipse and more powerful than any single storm system.”
According to the National Oceanic and Atmospheric Administration (NOAA), El Niño is developing in the Pacific Ocean, with an 83% chance of becoming the strongest event of its kind since 1950. It could wreak havoc on normal weather patterns worldwide, triggering heavy rains, droughts, and storms.
El Niño and La Niña
When the Pacific Ocean is experiencing normal weather conditions, trade winds “blow west along the equator, taking warm water from South America towards Asia,” according to NOAA’s National Ocean Service. Sometimes, those normal conditions are broken up by opposing climate patterns known as El Niño and La Niña.
When El Niño strikes, trade winds weaken. Warm water is pushed toward the west coast of both North and South America. The name, which means “little boy” in Spanish, was first used among South American fishermen, who noticed “periods of unusually warm water” in the 17th century.
During La Niña, on the other hand, Pacific coast waters turn cold and the number of nutrients increases. The environment “supports more marine life and attracts more cold-water species, like squid and salmon, to places like the California coast.” La Niña, Spanish for “little girl,” gets its name from being the opposite of El Niño.
El Niño and La Niña episodes can last for years, but they usually run just nine to 12 months. The climate events typically make an appearance every two to seven years, with El Niño occurring more often than La Niña.
NASA Spots El Niño
The first sign of this year’s El Niño appeared in January in NASA satellite imagery showing a swell of warm water known as a Kelvin wave near the western Pacific region of Micronesia.
“Kelvin waves are slow-moving pulses of water thousands of miles long. Like underwater freeways, they transfer heat from west to east across the Pacific,” NASA explained. “The warm water heats the air directly above it, making it rise.”
The waves cause changes in air pressure that can weaken trade winds or change their direction, triggering sea level and water temperature fluctuations. “This chain reaction signifies the start of an El Niño,” the space administration added.
Why This Matters
The heavy rains, droughts, and storms brought on by El Niño can cause widespread damage to homes, businesses, farmland, and coastlines, resulting in billions of dollars in economic losses. “El Niño and La Niña can both have global impacts on weather, wildfires, ecosystems, and economies,” NOAA explained.
Understanding weather patterns helps officials anticipate potentially dangerous conditions and take steps to protect people around the world. “El Niño touches almost all of us in some way every time it occurs,” said Josh Willis, project scientist at NASA’s Southern California-based Jet Propulsion Laboratory. “While many have seen what it can do, we look to the ocean to understand why.”
4 Questions
The story, in brief
What is El Niño, and why is NASA tracking it now?
El Niño is a climate pattern in the Pacific Ocean that develops when trade winds weaken and warm water shifts toward the west coast of North and South America. NASA is tracking it because NOAA says there is an 83% chance it could become the strongest El Niño since 1950 and disrupt weather worldwide.
How did NASA detect the 2023 El Niño in the Pacific Ocean?
NASA first saw signs in January through satellite imagery that showed a swell of warm water called a Kelvin wave near the western Pacific region of Micronesia. These slow-moving pulses carry heat from west to east across the Pacific, heating the air above and helping trigger the chain reaction that marks the start of an El Niño.
How does El Niño differ from La Niña in the Pacific Ocean?
El Niño happens when trade winds weaken and warm water moves toward the Pacific coasts of North and South America. La Niña is the opposite pattern, with colder Pacific coast waters and more nutrients. Those conditions support more marine life and attract cold-water species such as squid and salmon to places like the California coast.
Why can a strong El Niño matter for people around the world?
El Niño can disrupt normal weather patterns and trigger heavy rains, droughts, and storms across the globe. Those effects can damage homes, businesses, farmland, and coastlines, leading to billions of dollars in economic losses. Officials study these patterns so they can anticipate dangerous conditions and better protect people.
