Extreme weather caused by El Niño can include major floodingAntonio Masiello/Getty Images
El Niño has officially begun, and it’s more likely than not that it will develop into a “super” El Niño. Either way, it will amplify temperatures and extreme weather around the world.
El Niño is a natural climate phase that occurs when east-to-west winds weaken in the tropical Pacific, allowing water concentrated in the “warm pool” on the western side of the Pacific to wash back towards the eastern side. This broad smear of warm water heats the atmosphere, raising the global temperature.
The US National Oceanic and Atmospheric Administration (NOAA) has now declared the onset of El Niño because sea surface temperatures in the central-eastern Pacific have been more than 0.5°C above normal for the past month, and climate models project they will remain there for at least the next six months. The Japan Meteorological Agency has also declared that El Niño has begun.
“We are seeing westerly wind anomalies from the dateline almost all the way to about 130° west, so basically the entire area south of Hawaii,” says Matthew Rosencrans at NOAA’s National Weather Service. “What that means is significantly reduced trade winds there, so it’s allowing the atmosphere and the ocean to slosh to the east and bring that warm water with it.”
