What does the return of El Niño mean?

{"text":[[{"start":7.28,"text":"One of the most powerful naturally occurring climate patterns on Earth is under way, with multiple weather agencies around the world tracking its gathering strength as it warms the equatorial Pacific Ocean."}],[{"start":18.94,"text":"The cyclical shift in circulation in the Pacific Ocean to the warm phase, known as El Niño, is expected to peak in November or December and persist until at least February, the World Meteorological Organization said in early September."}],[{"start":33.32,"text":"The effect so far is the rise in central and eastern equatorial sea surface temperatures by more than 2C in August, which is defined as “very strong”."}],[{"start":43.16,"text":"The temperature rise in some parts was as much as an extraordinary 8C, the WMO officials said, with the levels of warmth diverging widely between the westernmost and easternmost regions."}],[{"start":54.04,"text":"Sea surface temperatures in the central and tropical Pacific first passed the 0.5C threshold that US scientists use to define the beginning of the cycle in June."}],[{"start":64.08,"text":"The sustained rise in equatorial Pacific temperatures beyond 2C would make this El Niño cycle among the most significant in the historical record going back to 1950."}],[{"start":74.88,"text":"The WMO said that present forecasts were that it could hit a high of 3.6C of warming — although the peak level and timing was less certain."}],[{"start":83.92,"text":"El Niño’s cyclical temperature swing in the Pacific Ocean matters because it typically elevates temperatures around the globe and exacerbates extreme weather events."}],[{"start":93.2,"text":"This year, it threatens to place stress on global health and agricultural systems at a time when economies are already under strain as a result of the Middle East war."}],[{"start":103.04,"text":"Celeste Saulo, the secretary-general of the WMO, said the warming of the Pacific Ocean could reach levels which were “off the charts” based on measurements for the past four decades, when modern monitoring began."}],[{"start":115.24,"text":"What is the effect of El Niño on global weather and trade?"}],[{"start":118.58,"text":"In general, El Niño events worsen both drought and heavy rainfall, while increasing the risk of heatwaves on land and at sea."}],[{"start":126.24,"text":"The name, meaning “little boy” in Spanish, was coined by South American fishermen who first noticed periods of unusually warm water in the Pacific Ocean in the 1600s. The reverse cooling effect is called La Niña, or “little girl”."}],[{"start":null,"text":""}],[{"start":139.4,"text":"El Niño is typically associated with higher rainfall in parts of southern South America, the southern United States, parts of the Horn of Africa and central Asia, the WMO says. Conversely, it is linked to drier conditions over Central America, northern South America, the Caribbean, Australia, Indonesia and parts of southern Asia."}],[{"start":160,"text":"During the northern hemisphere summer, El Niño can also fuel hurricanes in the central and eastern Pacific Ocean, while lessening hurricane formation in the Atlantic Ocean."}],[{"start":169.52,"text":"Trade and agricultural output can be disrupted, along with fisheries losses, damaged infrastructure, raised transport costs and commodity price volatility."}],[{"start":null,"text":""}],[{"start":178.88,"text":"But the effects are not universal. El Niño in 2015 and 2016 triggered the worst drought in southern Africa in 35 years, for example, and cut regional maize production by roughly a quarter. Food inflation levels in OECD countries were not affected, however."}],[{"start":194.62,"text":"The intensity, duration and time of year and other ongoing climate variables will affect how the El Niño ultimately manifests."}],[{"start":202.76,"text":"Richard Seager, a climate scientist at Columbia University, said that even in the case of a strong El Niño there is no guarantee these knock-on effects would happen. “The stronger the event, the more likely certain outcomes around the world are in terms of weather and climate, but still never getting up to an actual certainty.”"}],[{"start":220.76,"text":"What is a ‘Godzilla’ El Niño?"}],[{"start":222.52,"text":"Some observers have referred to the upcoming El Niño as “super” or “Godzilla”. James Hansen, an American climatologist, has even called this year’s phenomenon “super-duper”."}],[{"start":234.04,"text":"Scientists typically do not classify the event in such terms. The WMO’s preferred framework goes from “weak” and “moderate” through to “strong” or “very strong”. Its estimates are based on consensus models of its own research and climate prediction centres around the world."}],[{"start":248.64,"text":"The US’s National Oceanic and Atmospheric Administration uses a defined threshold. What it classes as a weak event involves 0.5C warming in the central and eastern Equatorial Pacific, based on a rolling three-month average temperature anomaly. Australia’s Bureau of Meteorology, watching for the effects on one of the world’s worst affected countries, puts that bar at 0.8C."}],[{"start":271.6,"text":"Warming of at least 1C is classed as moderate, 1.5C as strong, and 2C of warming of the ocean reaches the level of “very strong”, based on the Noaa ranking system."}],[{"start":null,"text":""}],[{"start":282.1,"text":"How long will El Niño last?"}],[{"start":283.84,"text":"The cycles of El Niño and its opposite cooling La Niña phenomenon usually take place every two to seven years, but do not have a regular schedule."}],[{"start":291.88,"text":"Generally, El Niño occurs more frequently than La Niña, but the patterns can become locked, as occurred from 2020–2023 when an unusual “triple dip” in the cooling cycle took place."}],[{"start":304.04,"text":"The intensity and global weather effects of an El Niño event usually peak during the northern hemisphere winter, between November and February."}],[{"start":312.24,"text":"The consequences for global temperatures are often most pronounced in the second year after it develops. The most recent El Niño event in 2023 and 2024 was one of the strongest on record, and in turn helped make 2024 the hottest year on record."}],[{"start":328.72,"text":"The present El Niño conditions are expected to strengthen into the northern hemisphere winter of 2026-27."}],[{"start":336.52,"text":"Forecasters watch for shifts in the cycle up to six months in advance. The warmer-than-usual ocean temperatures linked to El Niño occur when easterly trade winds weaken or reverse direction."}],[{"start":347.46,"text":"How does climate change interact with El Niño and La Niña?"}],[{"start":351.48,"text":"Human-caused greenhouse gas emissions, mainly from the burning of fossil fuels for energy and transport, have been the main driver of climate change."}],[{"start":359.2,"text":"But the pendulum swings from El Niño to La Niña can map on to levels of global warming, providing a short-term acceleration or deceleration in the long-term temperature trend."}],[{"start":369.36,"text":"The relationship also works in reverse. While climate change does not directly cause El Niño it can “amplify” its effects, the WMO explains."}],[{"start":378.4,"text":"This is because warmer oceans and air increase the availability of energy and moisture for extreme weather events such as heatwaves or heavy rain."}],[{"start":null,"text":""}],[{"start":387.38,"text":"As global warming has turbocharged ocean temperatures, it has also made it more difficult for scientists to keep using short-term localised temperature fluctuations as a measure of El Niño."}],[{"start":398.36,"text":"Some scientists now favour a “relative” measure that accounts for underlying tropical ocean heating."}],[{"start":403.86,"text":"A recent Science journal study submitted for peer review has sought to draw a link with global warming, based on monitoring of coral in the Galápagos Islands. But the journal has also reported that historical records are too short to reveal a clear trend."}],[{"start":418.36,"text":"But WMO’s Saulo this month noted that El Niño was not caused by climate change and was a result of natural climate variability. There was no established link between climate change and El Niño frequency or strength, she said."}],[{"start":432.2,"text":"“Of course, if we expect warmer [ocean] temperatures on top of a warming world, certainly the amount of heat into the system will be larger,” Saulo said."}],[{"start":440.92,"text":"*The graphic on El Niño’s effect on weather and crops has been amended and updated since original publication"}],[{"start":441.42,"text":"Additional reporting by Emiliya Mychasuk"}],[{"start":null,"text":""}],[{"start":null,"text":""}],[{"start":441.92,"text":"Letter in response:"}],[{"start":451.8,"text":"Assessing impact of El Niño requires a forward-looking model / From Isaam Hanif, Head of Science and Research at SLR Bristol, UK"}],[{"start":458.56,"text":""}]],"url":"https://audio.ftcn.net.cn/album/a_1789008095_5387.mp3"}