This particular La Niña was unusual and one of the longest on record.
washington • After three grim years, the La Niña weather phenomenon that is increasing Atlantic hurricane activity and exacerbating western drought is gone, the National Oceanic and Atmospheric Administration said Thursday.
That’s usually good news for the United States and other parts of the world, including drought-stricken Northeast Africa, scientists said.
The globe is now in a so-called “neutral” state and is likely trending toward a late summer or fall El Niño, said climate scientist Michelle L’Heureux, director of NOAA’s El Niño/La Niña forecasting office.
“It’s over,” said research scientist Azhar Ehsan, who leads Columbia University’s El Niño/La Niña forecast. “Mother Nature thought of getting rid of this one because it’s enough.”
La Niña is a natural and temporary cooling of parts of the Pacific Ocean that is changing weather around the world. Because La Niñas are associated with more Atlantic storms in the United States and deeper droughts and wildfires in the West, La Niñas are often more damaging and costly than their more famous downside, El Niño, experts said and studies show.
In general, La Niña damages American agriculture more than El Niño. If the globe bounces in El Niño, it means more rain for the corn belt and Midwest crops in general, and could be beneficial, said Michael Ferrari, chief scientific officer of Climate Alpha, a company that advises investors on financial decisions Basis of climate advises.
When there is a La Niña, there are more Atlantic storms during hurricane season because it eliminates conditions that suppress storm formation. Neutral or El Niño conditions make it harder for storms to get going, but aren’t impossible, scientists said.
In the past three years, the United States has been hit by 14 hurricanes and tropical storms that caused $1 billion or more in damage, totaling $252 billion, according to NOAA economist and meteorologist Adam Smith. La Niña and people building in dangerous ways were factors, he said.
Climate change is a major contributor to worsening extreme weather conditions alongside La Niña, scientists said and numerous studies and reports show. Human-caused warming is like an upward escalator: It causes temperatures to rise and extremes to worsen, while La Niña and El Niño are like hopping up and down the escalator, according to Victor Gensini, a professor of atmospheric sciences at Northern Illinois University .
La Niña has also moderately dampened average global temperatures, preventing warming from breaking annual temperature records, while El Niño boosts those temperatures slightly and often sets records, scientists said.
La Niña tends to wet West Africa but dry East Africa, around Somalia. The opposite is happening in El Niño, where drought-stricken Somalia is likely to get steady “short rains,” Ehsan said. La Niña has wetter conditions for Indonesia, parts of Australia, and the Amazon, according to NOAA, but those areas are drier in El Niño.
El Niño means more heat waves for India and Pakistan and other parts of South Asia and weaker monsoons there, Ehsan said.
This particular La Niña, which began in September 2020 but is believed to be three years old because it spanned three different winters, was unusual and one of the longest on record. It took a brief hiatus in 2021 but came back with record intensity.
“I’m sick of this La Niña,” Ehsan said. L’Heureux agreed and said she was willing to talk about something else.
The few other instances of triple collapses in La Niña have come after strong El Niños, and there are clear physical reasons why this is happening. But that didn’t happen with this La Niña, said L’Heureux. This one did not have a strong El Niño before.
Although this La Niña has puzzled scientists in the past, they say the signs are clear: the waters in the central part of the central Pacific warmed to just above the threshold for a La Niña in February, the atmosphere showed some changes and along the eastern Pacific near Peru there is already El Niño-like coastal warming, L’Heureux said.
Think of La Niña, or El Niño, as something shifting the weather system out of the Pacific with ripple effects around the world, L’Heureux said. In neutral conditions like this there is less thrust from the Pacific. That means other climatic factors, including the long-term warming trend, have a greater impact on daily weather, she said.
Without an El Niño or La Niña, meteorologists have a harder time predicting summer or fall seasonal weather trends because the Pacific Ocean has such a large footprint in week-long forecasts.
El Niño forecasts made in the spring are generally less reliable than those made at other times of the year, leaving scientists less certain about what will happen next, L’Heureux said. But NOAA’s forecast says there’s a 60 percent chance El Niño will prevail in the fall.
There is also a 5% chance that La Niña will return for an unprecedented fourth slump. L’Heureux said she really doesn’t want that, but the scientist in her would find it interesting.
https://www.sltrib.com/news/nation-world/2023/03/09/la-nia-which-worsens-hurricanes/ La Niña, which exacerbates hurricanes and droughts, is gone