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La Nina is over, National Weather Service declares - The Washington Post

La Nina is over, National Weather Service declares – The Washington Post

An extended episode of the global climate pattern known as La Niña is over, and scientists suspect a “rapid evolution” to El Niño — known for accelerating planetary warming and inducing extreme weather — could occur this summer.

That is according to the latest analysis from the National Weather Service Climate Prediction Center, which said Thursday that the markers of La Niña all but disappeared in February. La Niña is associated with cooler-than-normal waters in the tropical Pacific Ocean and can promote more intense Atlantic hurricanes.

Instead, surface temperatures across most of the equatorial Pacific have surged in recent weeks, a potential sign of El Niño. For now, scientists say Earth’s climate is in neutral — with neither La Niña or El Niño influencing global weather patterns.

The probable return of El Niño raises concerns about how it could accelerate global warming and crises of climate change. The last major El Niño episode in 2016 sent average global temperatures to record highs and contributed to devastating rainforest loss, coral bleaching, polar ice melt and wildfires.

Disturbed polar vortex bringing delayed dose of winter to eastern U.S.

El Niño events that intense typically occur about once every 15 years on average, so it remains to be seen — if another episode begins this year — whether it could pack such a punch, said Michael McPhaden, a senior scientist at the Pacific Marine Environmental Laboratory in Seattle.

“It may not be one of these blockbusters; it may be garden variety,” said McPhaden, who works for the National Oceanic and Atmospheric Administration but is not involved in its El Niño forecasting. “It could have some significant impacts around the world.”

La Niña had been in place since 2020, but for a brief interlude of neutral conditions in 2021.

In the United States, it is known for driving colder and wetter conditions across the northern contiguous states and mild and dry weather in the southern tier. And it has a temporary cooling influence around much of the world, including in Alaska and southern Africa and Asia.

La Niña can also encourage tropical cyclone formation and intensification in the Atlantic basin because it is associated with reduced wind shear — variation in wind speeds and direction at different altitudes — there.

El Niño, on the other hand, can trigger droughts in northern Australia, Indonesia and southern Africa and above-average precipitation across the southern United States, including in Southern California. Atlantic hurricane activity is typically somewhat reduced.

But its larger impact is perhaps its larger warming influence.

Warmer-than-normal surface waters along the equatorial Pacific — the main measure used to gauge El Niño intensity — mean more evaporation along that vast stretch of ocean. That leads to increased water vapor in the air and the formation of clouds, which block the sun’s heat from reaching the ocean and encourage more of that warmth to be trapped in the atmosphere.

Still, El Niño’s arrival remains uncertain, the climate forecasters stressed.

They predict just greater than 50-50 odds of El Niño in late summer, approaching a two-in-three chance by fall. And they note that any predictions made during the spring regarding El Niño or La Niña “are less accurate” because the climate is typically in transition at this time of year.


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