El Niño, the natural climate pattern linked to warmer conditions in the tropical Pacific Ocean, has ended, the National Oceanic and Atmospheric Administration announced on Thursday. The counterpart pattern known as La Niña, defined by cooler equatorial sea surface temperatures, is expected to develop soon.
A strong El Niño has cycled through the atmosphere since last June, leading to a wetter than normal winter, especially in the Southeast and in California, where a mind-boggling 51 atmospheric rivers dumped rain and snow. Now, a brief period of neutrality is upon us, but climate scientists predict that La Niña could form as early as July, a likelihood that increases as the calendar flips closer to winter.
While climate change remains the biggest factor in extreme weather events, experts say La Niña could tip the scales toward an even more active hurricane season.
That’s because, while El Niño conditions can rip apart storms that develop in the Atlantic Basin, hurricanes and tropical cyclones are more likely to form under La Niña. Calm conditions produced by La Niña combined with warm ocean temperatures will intensify the activity likely to occur during hurricane season. Temperatures at the surface of the Atlantic Ocean have been increasing since 2016 and broke marine heat records last summer.
The NOAA Climate Prediction Center has forecast that up to 13 hurricanes could develop in the Atlantic Ocean this year, at least four of which could be major.
Matthew Rosencrans, NOAA’s lead meteorologist for the seasonal hurricane outlook, said the five years that most closely resembled this year’s forecast had all occurred in the last two decades. Years of particular note include 2005, when Hurricane Katrina devastated New Orleans; 2017, when hurricanes cost the United States more than $300 billion in damages; and 2020, which saw 11 out of 30 named storms pummel the coastline of the United States.
“People should be preparing as if a hurricane could impact them this year,” Mr. Rosencrans said. “I want people to stay safe. Preparing now reduces stress later, and if they’re more prepared, they could potentially save their own life.”
El Niño and La Niña are opposing climate patterns that shift where rainfall occurs in tropics, said Michelle L’Heureux, a climate scientist at the NOAA Climate Prediction Center. That shift leads to a ripple effect on the jet stream and atmospheric circulation over North America, which affects weather in far-flung areas of the world. La Niña, for example, tends to push the jet stream northward.
In the United States, that tends to mean the northern tier of states tends to have colder temperatures with more rain and snow throughout the winter months and early spring, while the southern half tends to be drier and warmer.
Historically, El Niño has also increased the global mean air temperature, while La Niña has decreased it, but the strong arm of climate change means global temperatures are constantly swinging upward.
“It’s not as big of a player as it used to be,” Ms. L’Heureux of said El Niño and La Niña, known collectively as ENSO, for the El Niño-Southern Oscillation. Three of the last five years were La Niña cycles, which tend to cool the climate, yet the world still saw the highest global temperatures on record.
Now, Ms. L’Heureux said, “El Niño and La Niña are just changing the details.”
Source link: https://www.nytimes.com/2024/06/14/climate/el-nino-la-nina.html