The looming El Niño could be bad – but much worse is to come

Newspaper headlines have been buzzing about an impending “Godzilla El Niño.” In reality, there is an 80 percent likelihood that an El Niño will develop by September. Most forecasts predict a moderate event, although some indicate it could be exceptionally strong, possibly reaching the level of a super El Niño.

The broader outlook remains troubling. Regardless of the intensity of this El Niño, more severe occurrences are expected in the future. Even if future El Niños are not stronger, their impacts will be exacerbated by a warming climate.

“Even a standard El Niño event in the future will lead to greater regional and global effects,” states Axel Timmermann from Pusan National University in South Korea.

Alarmingly, research by Timmermann and others indicates that El Niños and La Niñas, collectively known as ENSO events, will intensify and begin influencing Atlantic weather patterns, magnifying their effects.

“Our recent computer model simulations forecast a trend toward more frequent and intense El Niño-La Niña extremes, along with heightened ENSO impacts on distant regions, particularly Europe,” Timmermann explains.

The El Niño phenomenon revolves around the interplay of water and winds in the Pacific. Under neutral conditions, trade winds push warm surface water westward along the equator, accumulating it in the western Pacific. This displacement causes cold water to rise near South America, replacing the moved surface water, while warm air rises above the heated western waters, resulting in heavy rainfall.

Occasionally, these trade winds weaken or reverse, allowing the warm water to spread eastward. This shift in rainfall can further invigorate easterly winds, creating a feedback loop that fosters El Niño development. This movement causes droughts in regions like Australia and Indonesia, while South America experiences flooding.

El Niños also lead to rapid planetary warming. The expansion of warm water increases evaporation, and the energy from this evaporated water is released as latent heat during cloud formation, transferring significant heat from the Pacific to the atmosphere.

The strength of El Niños is assessed by the extent to which warm water travels east towards South America, measured by the rise in central and eastern Pacific temperatures. While definitions vary, an El Niño occurs when sea-surface temperature anomalies exceed 0.5°C. According to Adam Scaife at the Met Office Hadley Centre in the UK, a super El Niño might be classified for anomalies above 2°C, and a Godzilla El Niño for those surpassing 3°C.

As El Niños evolve, negative feedback loops also emerge. Increased cloud cover over the central Pacific has a cooling effect, leading to a return to neutral conditions or a shift to La Niña, where strengthened westerly trade winds push cooler upwelling water further west.

The three most intense El Niños on record occurred in 1982-83, 1997-98, and 2015-16, each causing substantial harm to people and ecosystems, including massive coral die-offs and other marine life losses.

Each of these super El Niños also resulted in trillions in damages, as highlighted by a 2023 study from Christopher Callahan at Indiana University. “Our findings indicate that the economic damage correlates directly with the ocean temperature strength in the Pacific,” Callahan notes. “A significant El Niño this year could entail similar economic losses.”

As global temperatures rise, upcoming El Niños and super El Niños are expected to inflict even more damage. “The science is very clear,” affirms Richard Allan from the University of Reading, UK.

ENSO-related floods are projected to intensify due to increased atmospheric moisture, resulting in heavier rainfall, says Allan. Additionally, droughts will likely be more prolonged and severe, as higher temperatures accelerate soil drying.

Some climate models suggest that warming may intensify the feedback loops driving ENSO events. This could result in stronger El Niños and La Niñas, with quicker transitions between them, a phenomenon dubbed “climate whiplash,” further challenging societal adaptation to a warming world.

“This would mean much larger swings between years with above-average rainfall and years with drought in many global regions,” comments Malte Stuecker from the University of Hawaiʻi, who is part of Timmermann’s team.

Even more concerning, the study suggests these pronounced fluctuations could lead ENSO events to influence and synchronize with the North Atlantic oscillation, resulting in significant shifts between floods and droughts in Europe.

“This would represent a major regime shift for Europe, as currently, El Niño does not heavily influence European weather patterns,” Stuecker notes.

While there is strong confidence that El Niños of similar intensity will become more destructive, there is less certainty about whether El Niño itself will grow more intense. “There is considerable debate about the future behavior of El Niño and La Niña,” states Scaife.

Not all climate models predict a strengthening of El Niños, he says. However, many agree that the connections with areas like the Atlantic will strengthen, indicating that El Niño’s effects beyond the Pacific will likely increase.

Even if ENSO events do grow stronger, they are unlikely to intensify indefinitely, according to Timmermann. The intensification is partly driven by the rapid warming of the top 100 meters of the Pacific. Once the deeper waters warm and the temperature difference decreases, ENSO events are expected to weaken.

The caveat? This reduction might not occur until after 2150. Prepare for a bumpy ride.