Why this El Niño is already record-strong: two clear causes

The useful part

This will no doubt be the subject of many studies to come, but the broad picture is clear. Two main factors have driven the formation of this record-smashing El Niño, the first of which was set in motion long before it began. To understand this El Niño, we have to understand La Niñas, the opposite phase of the climate pattern.

How it works

• Advertisement Read more 5 graphs that show how the record-breaking El Niño will affect the world The bigger the warm pool gets, the more unstable it becomes.
• So the extent to which an El Niño raises global temperatures and causes extreme weather depends on how big and hot the warm pool gets, and on how much of it moves east across the Pacific.
• Each wind burst creates a downward bulge in the layer of warm water, known as a Kelvin wave, which travels across the Pacific over the following six to eight weeks.
• Spectacular feathered dinosaur fossil shows bird-like adaptations The best new science-fiction books of October 2026 Our food system is vulnerable to El Niño, warns UK climate minister Explainer:
• From back pain to cancer, how the interstitium could transform medicine Can you hack your brain to be ultra-productive?

What to take from it

During La Niñas, trade winds blow west across the equatorial Pacific, pushing surface waters warmed by the sun towards Australia and Indonesia. It really does pile up: sea level in the western Pacific rises as much as 20 centimetres. If the trade winds holding it in place weaken or reverse direction, the warm water spills back across the Pacific, making surface waters along the equator abnormally warm – an El Niño event.

Example or evidence

• "Based on that alone, one might not have expected this event to become as strong as it has," says McPhaden.
• The second key factor was a series of strong bursts of wind blowing east, pushing the extra-hot warm pool towards South America.
• Put another way, the bottom of the warm layer, or thermocline, becomes deeper.

Details worth keeping

So, what has made this such an exceptional event? This piles up a layer of water known as the "warm pool". The warm pool gets hotter during La Niñas and colder during El Niños, but temperatures have been increasing over the past decades due to global warming, says Michael McPhaden at the US National Oceanic and Atmospheric Administration.

Related coverage

• Cbsnews: While El Niño is a natural shift in the climate system, scientists say the weather pattern developing in the Pacific Ocean could be one of the strongest on record.
• Rappler: 'El Niño is being supersized before our eyes. The science leaves no room for doubt: The planet is in uncharted waters, and those waters are heating up,' says United Nations chief Antonio Guterres
• Insurancejournal: The powerful El Niño that's already disrupting global weather patterns has a 75% chance of becoming "a historic event," surpassing all records dating back to 1950, the US Climate Prediction Center said.
• Huffingtonpost: A 'Godzilla' El Niño is brewing – and scientists are concerned about how the weather phenomenon is set to impact the UK and wider world.