Headlines are suggesting an impending “Godzilla El Niño.” In reality, the likelihood of an El Niño developing by September stands at 80 percent. While most climate models predict a moderate event, some foresee the possibility of a very strong one, perhaps even a so-called super El Niño.
However, the overall outlook is far from optimistic. Regardless of the strength of this particular El Niño, it’s virtually certain that more destructive events will occur in the coming decades. Even if future events aren’t more severe, their impacts will be magnified by a warming climate.
“Even a standard El Niño event will cause more widespread regional and global impacts in the future,” states Axel Timmermann from Pusan National University in South Korea.
Even more concerning, research by Timmermann and others indicates that El Niño and La Niña events – collectively known as ENSO phenomena – will also intensify significantly, influencing weather in the Atlantic and amplifying their effects.
“Our latest computer models predict a shift towards more regular and much stronger extreme El Niño-La Niña events, as well as an amplified ENSO influence on distant regions, particularly Europe,” Timmermann adds.
The El Niño phenomenon is linked to ocean temperatures and winds in the Pacific. Under so-called neutral conditions, trade winds blow westward along the equator, pushing surface waters towards the west and accumulating warm water along the western Pacific. Cooler water wells up off the coast of South America, replacing the surface waters pushed west. Simultaneously, warm, moist air rises over the accumulated warm waters in the west, triggering heavy rainfall.
Occasionally, however, these trade winds weaken or even reverse, allowing some of that warm water to flow eastward. The area of rainfall also shifts eastward, potentially strengthening easterly winds – a positive feedback mechanism that drives El Niño development. This eastward shift also leads to droughts in places like Australia and Indonesia and floods in South America.
This is precisely why El Niño causes the planet’s surface temperature to rapidly warm. The increased expanse of warm water leads to enhanced evaporation, and the water’s energy is released as latent heat when clouds form, transferring vast amounts of heat from the Pacific Ocean into the atmosphere.
The strength of an El Niño is determined by how much and how far east the warm water moves towards South America. This is measured by how much warmer than average the central and eastern Pacific becomes. While definitions vary, El Niño is considered to occur when sea surface temperature anomalies exceed 0.5°C. “Super El Niño” is not a scientific term but could be used for events with temperatures above 2°C, and “Godzilla El Niño” for those exceeding 3°C, suggests Adam Scaife of the Met Office Hadley Centre in the UK.
As El Niño progresses, negative feedback loops are also triggered. Specifically, increased cloudiness over the central Pacific exerts a cooling influence, leading to a return to neutral conditions or a transition to La Niña, where the westerly trade winds strengthen and push the upwelling colder water further west than usual.
The three strongest El Niño events since record-keeping began occurred in 1982-83, 1997-98, and 2015-16. All three caused extensive damage to both human populations and wildlife, leading to mass coral bleaching and the death of other marine creatures.
Each of these super El Niños also resulted in trillions of dollars in economic damage, according to a 2023 study by Christopher Callahan of Indiana University. “Our findings suggest the scale of economic losses is directly tied to the Pacific Ocean temperatures,” Callahan states. “If we have a significant El Niño this year, we should expect trillions of dollars in economic losses, similar to previous events.” As global warming progresses, future El Niño – and super El Niño – events will inflict even greater damage. “The scientific evidence is crystal clear,” says Richard Allan from the University of Reading, UK.
ENSO-related floods will become more intense because there will be more moisture in the atmosphere, Allan explains, meaning more rainfall will occur. Droughts will also become more prolonged and severe as soil dries out faster in hotter conditions.
Some climate models also suggest that warming will amplify the feedback mechanisms that drive ENSO events. This could lead to stronger El Niños and La Niñas with more rapid transitions between them – a greater “climate whiplash” – making it even harder for society to adapt to a warming world.
“This will mean much larger swings between years with more-than-average rainfall and drought years in many regions of the world,” says Malte Stuecker of the University of Hawaii.
Worse still, the team’s research suggests these amplified swings will cause ENSO events to begin influencing and synchronizing with a climate pattern known as the North Atlantic Oscillation. This will also lead to sharp swings between floods and droughts in Europe.
“This would be a major regime shift for Europe, as under current climate conditions we don’t see a significant El Niño impact on European weather,” Stuecker notes.
While there is high confidence that an El Niño of the same strength will be more damaging, there is much less certainty that El Niños will become more intense. “There is quite a bit of disagreement about the future behavior of El Niño and La Niña,” Scaife remarks.
Not all climate models predict an intensification of El Niño, he says. But many still agree on a stronger linkage with regions like the Atlantic, meaning El Niño’s impacts outside the Pacific are likely to become even more pronounced in the future.
Even if ENSO events do become more intense, they will not continue to strengthen indefinitely, Timmermann explains. The intensification is partly driven by the rapid warming of the top 100 meters of ocean water across much of the Pacific. Once the deeper waters begin to warm, and the temperature difference lessens, ENSO events are likely to weaken, he suggests.
What’s the catch? This weakening may not begin until after 2150.
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