ANALYSIS: A strong El Nino may be imminent. Climate change will make its effects worse

BRUSSELS — The El Niño weather pattern is forming and is expected to cause extreme weather around the world this year, the World Meteorological Organization (WMO) said on Tuesday. Scientists warn that climate change will make its impact especially severe.

The WMO stated there is an 80% chance that an El Niño event will develop between June and August, and a 90% chance it will last until at least November. This statement is the clearest signal yet of the likelihood of the event.

The El Niño phenomenon naturally occurs every two to seven years when weakening trade winds result in warmer waters in the eastern Pacific Ocean. The result tends to be higher global temperatures and disrupted rainfall — meaning severe drought in some regions and heavy rains in others. It also directly affects hurricane formation.

Two distinct factors make this year's forecast particularly worrying.

1. A Higher Intensity Threat

The first concern is the chance that this year's El Niño — and its subsequent impact — will be stronger than typical historical averages.

While the WMO noted there is still uncertainty, and some models predict a "strong" El Niño while others do not, current forecasts suggest a strong event is highly possible. A strong El Niño is defined by sea surface temperatures in the eastern Pacific rising at least 1.5 degrees Celsius (2.7 degrees Fahrenheit) above average.

2. The Climate Change Multiplier

The second major cause for concern is ongoing climate change. Greenhouse gas emissions have already increased the planet's average temperature by around 1.3°C since pre-industrial times.

That higher baseline supercharges the natural effects of El Niño — enabling higher temperature spikes, more intense droughts, heatwaves, extreme rains, and resulting disasters, including bushfires, floods, and crop failures.

"When we get an El Niño, because of the underlying climate change... these things become more intensified and they're more impactful," said Piers Forster, Professor of Physical Climate Change at the University of Leeds.

The combination of climate change and El Niño has led the WMO to warn that 2027 could be the hottest year since records began. The last El Niño year, 2024, currently holds the record and was regarded by the WMO as exceptionally strong.

'The Risks Are Enormous'

Each El Niño is unique, and its effects vary across the globe, making it difficult to predict exactly how this upcoming cycle will behave.

Typically, regions including southern South America and parts of Central Asia receive more rain during an El Niño, while Central America and Australia dry out. The phenomenon also intensifies heatwaves, even in regions far from the Pacific, such as Europe. These shifts can have disastrous consequences for global food production, local industries, and human life.

South America: In April and May of 2024, floods in Rio Grande do Sul, Brazil, killed more than 180 people and displaced 600,000. Scientists confirmed that both climate change and El Niño strengthened the rains that triggered the disaster. Francisco Aquino, head of the University of Rio Grande do Sul's climate center, said a strong El Niño this year risks causing a similar disaster.

"When you have an El Niño over what climate change already brought, the risks are enormous," Aquino told Reuters. "A strong El Niño can lead to the exact same scenario we saw then, because the world keeps getting warmer, and the temperature in the ocean keeps rising."

Southern Africa: Climate change is compounding the impact of El Niño here as well. In this region, the weather pattern drastically reduces rainfall during the main rainy season, limiting hydropower generation and cutting crop yields.

"Climate change will make that below-normal rainfall more intense, so it will last longer or have less rainfall... and that, of course, will affect agriculture, especially the rain-fed farmers in the region," said Izidine Pinto, a Senior Climate Researcher at the Netherlands Meteorological Institute.

Pacific Cyclones: Antonio Navarra, head of Italy's Euro-Mediterranean Center on Climate Change, noted that stronger Pacific cyclones are another threat governments must prepare for. "Because the water in the Pacific will be much warmer, there will be a much more favorable environment for the formation of tropical cyclones... El Niño will input an enormous amount of energy into the system, so everything will be more intense," he said. -Reporting by Kate Abnett, additional reporting by Lisandra Paraguassu; editing by Barbara Lewis/Reuters