The powerful shifts in Pacific winds and water temperatures frequently push global temperatures to record-breaking levels. They can also transform global weather patterns, increasing the likelihood of severe droughts in places like Australia and Southeast Asia and heavy floods in parts of the US and East Africa. 

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By Martina Igini

El Niño has developed in the tropical Pacific and it is predicted to intensify to a “moderate or strong level” this fall, the National Oceanic and Atmospheric Administration (NOAA) said on Thursday.

The US agency declares an El Niño when temperatures in the equatorial Pacific are 0.5C above average for several consecutive months, according to its press release. If sea surface temperatures in the Nino-monitored region of the Pacific exceed 2C, then the event is considered “very strong.” Currently, NOAA predicts a 63% chance of that happening.

The global climatic phenomenon, which occurs every two to seven years on average, is associated with the warming of sea surface temperatures in the central and eastern tropical Pacific Ocean. When this happens, the east-to-west trade winds die, keeping warmer than the normal air in the eastern and central parts of the tropical Pacific, which temporarily raises global average temperatures. When combined with long-term human-caused climate change, these weather patterns frequently push global temperatures to record-breaking highs.

Prolonged and intensified heatwaves can heighten wildfire risk in some regions. They also increase demand for air conditioning, which can result in more burning of planet-warming fossil fuels to meet the rise in electricity demand. Extreme heat is also extremely dangerous to the human body and can be deadly if symptoms are not promptly treated. Outdoor workers, children and the elderly, pregnant women, those living in informal settlements and the unhoused are particularly at risk.

The past two such events – in 2014-16 and 2023-24 – brought record heat around the world that fueled further global temperature increase. 2024 went down as the hottest year on record due to a combination of long-term human-caused climate change and a strong El Niño weather pattern. Now, its return increases the chances of another record warm year – likely to be 2027.

The powerful shifts in Pacific winds and water temperatures typically also bring erratic weather patterns globally, such as increased likelihood of severe droughts in places like Australia, sub-Saharan Africa and Southeast Asia and heavy floods in parts of the southern US, South America, the Horn of Africa and central Asia.

Droughts have the potential to decimate crops, particularly maize, rice, and wheat, affecting global food supply chains that are already suffering from a fertilizer crisis caused by the closure of the strait of Hormuz. In the Americas, wet conditions are set to boost global soybean production.

El Niño also affects tropical cyclones. In the Atlantic basin, stronger upper-level winds typically suppress storm development, while weaker winds can enhance hurricane development in the eastern and central Pacific basin. In its Atlantic and eastern and central Pacific hurricane season outlooks released last month, NOAA predicted a 55% chance of below-average hurricane activity in the former and a 70% chance of above-average activity in the latter.

El Niño conditions also typically boost hurricane in the northwestern Pacific – known as typhoons in this part of the world. Typhoons take longer tracks over water during El Niño years, according to Yale Climate Connections. This is because warmer ocean waters are displaced toward the Central Pacific, causing tropical storms to form much farther to the east than usual. This elongated path provides more time for the storms to absorb heat and moisture, drastically increasing their odds of developing into major, catastrophic storms.

El Nino tends to be strongest during the winter months, with its global impacts typically most significant in the northern hemisphere winter, according to last week’s press release.

“Every El Nino is not the same; each one is unique with its own imprint on our weather,” said Ken Graham, Director of NOAA’s National Weather Service (NWS). “Advanced monitoring and an improved understanding of El Nino patterns allow the NWS to better predict and better prepare the public and our core partners for what is to come.”