The powerful El Niño weather phenomenon, which added some heat to already unprecedented global temperatures, has disappeared. Its reverse, La Niña, is expected to take hold just in time for peak Atlantic hurricane season, according to federal meteorologists.
The National Oceanic and Atmospheric Administration on Thursday declared the death of El Niño, which is warming parts of the central Pacific. Although it did not break all records for strength, the El Niño that formed a year ago was blamed, along with human-caused climate change and general ocean warming, for being the cause of twelve months of heat waves and extreme weather conditions.
The world today finds itself in a neutral situation regarding the significant natural El Niño Southern Oscillation (ENSO), which is distorting weather systems around the world. We speak of neutrality when weather conditions approach long-term averages or normal, which has not happened as often as before recently, said Michelle L’Heureux, a physical scientist at the NOAA and lead forecaster of the agency’s ENSO team. But that probably won’t last, she added.
She said there is a 65 percent chance that a La Niña, a cooling of the same parts of the Pacific that often has opposite effects, will form during the period of July, August and September. One of the main effects of La Niña is to make the Atlantic hurricane season, which peaks in August, more active.
“The likelihood of a La Niña, coupled with record sea surface temperatures, is why the National Hurricane Center is predicting an extraordinary hurricane season,” said Kathie Dello, Carolina state climatologist. North. States from Texas to Maine are gearing up for an active year. »
Both El Niño and La Niña create “potential hotspots” for extreme weather, but in different locations and of different types, L’Heureux said.
“La Niña tends to bring drier conditions in the southern United States in the winter, and when you add global warming to that, those drier conditions could turn into droughts,” she said. noted.
That’s because storm systems, mostly in winter, shift slightly northward due to a shift in the jet stream during La Niña years, which brings more rain and snow northward, Ms. The happy one.
Although La Niña years tend to be cooler, there will likely be a residual effect of the end of El Niño on global temperatures, L’Heureux added. Every month so far this year has broken world records.
A group of 57 scientists concluded earlier this month that no more than 8% of last year’s record heat could be attributed to El Niño and other factors of natural variability. The rest is due to human-caused climate change burning coal, oil and natural gas.
A 1999 economic study showed that La Niña drought cost U.S. agriculture between $2.2 billion and $6.5 billion, far more than the cost of El Niño ($1.5 billion). ). A neutral ENSO is the best solution for agriculture.
Since La Niña is linked to Atlantic hurricanes and drought in the United States, it makes sense that it is generally more costly, but every El Niño and La Niña is different, and citizens and governments must so prepare for it, underlined meteorologist and economist Michael Ferrari, scientific director of AlphaGeo, a company that works on financial investments and the climate.
The El Niño that just ended “didn’t break any records, but it probably ranked in the top five,” Ms. L’Heureux said. It raised the overall temperature and brought more humidity to the southern United States this year, as well as drier conditions in parts of South and Central America. The Horn of Africa was wetter.
Coral reef experts say the combination of record ocean temperatures and warming from El Niño has led to major bleaching globally, threatening and sometimes killing vulnerable corals.
Before this year’s El Niño, the world had experienced two consecutive La Niña periods, which is unusual, Ms. L’Heureux said. Some studies have shown that the planet should expect more El Niños and La Niñas ― and fewer neutral periods ― as the world warms, but the question is not yet clear-cut, he said. she adds.