Photo Credit: Courtesy Bar Ilan University
Prof. Shlomo Havlin

The significant weather phenomenon El Niño (pronounced el-ninyo, Spanish for “the Godly Child”) could soon occur again in the Pacific region, according to researchers from Justus Liebig University Giessen, the Potsdam Institute for Climate Impact Research, and Bar-Ilan University. While commonly used models do not currently show any signs of an upcoming storm, the researchers predict El Niño by the end of 2020.

El Niño affects the global climate and disrupts normal weather patterns, which as a result can lead to intense storms in some places and droughts in others. When El Niño conditions last for many months, its economic effect on local fishing for an international market can be devastating. El Niño can affect commodity prices and the economies of many countries. It can constrain the supply of rain-driven agricultural commodities; reduce agricultural output, construction, and services activities; create inflation; and may trigger social unrest in commodity-dependent poor countries that primarily rely on imported food.

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El Niño, which occurs when changing ocean conditions disrupt weather patterns, is in the forecast for 2020, according to the German and Israeli researchers. The prediction method they developed is based on an algorithm that relies on a network analysis of air temperatures in the Pacific region. This algorithm correctly predicted the last two El Niño events, in 2014 and 2018, more than a year in advance. Now it is predicting one by the end of 2020.

PROBABILITY OF AROUND 80%

“This novel climate network approach is very promising for improving El Niño prediction,” said Prof. Shlomo Havlin, an Israel Prize-winning physicist from Bar-Ilan University who was involved in developing the algorithm.

“Conventional methods are unable to make a reliable El Niño forecast more than six months in advance. With our method, we have roughly doubled the previous warning time,” stressed JLU physicist Armin Bunde, who initiated the development of the algorithm together with his former PhD student Josef Ludescher.

Hans Joachim Schellnhuber, Director Emeritus of Climate Impact Research, explained: “This clever combination of measured data and mathematics gives us unique insights – and we make these available to the people affected.”

He pointed out that the prediction method does not offer one hundred percent certainty: “The probability of El Niño in 2020 is around 80%. But that’s pretty significant.”

Josef Ludescher emphasized: “We also predicted the absence of another El Niño in 2019 at the end of last year. Only since July have official forecasts agreed with ours.”

The team is currently expanding the algorithm in order to be able to forecast the strength and length of the weather phenomenon in the future.

For their investigations, the researchers used a network of atmospheric temperature data in the tropical Pacific consisting of 14 grid points in the equatorial El Niño core area, and 193 points in the Pacific outside this core area. The physicists had discovered that already in the year before the eruption of an El Niño, the teleconnection effect between the air temperatures inside and outside of the core area becomes considerably stronger. In particular, they used this effect to optimize their prediction algorithm.

The prediction method was first published in 2013 in an article in Proceedings of the National Academy of Sciences (Very early warning of next El Niño). Reliable data from the period between the beginning of 1950 and the end of 2011 were available to the researchers for the investigations. The period between 1950 and 1980 served as a learning phase for determining the alarm thresholds. With the help of this algorithm, the El Niño events could then be predicted and compared with actual events. In 80 percent of the cases, the alarm was correct and the El Niño event could be accurately predicted the year before.

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