An integrated forecasting system allows for real-time El Niño-Southern Oscillation predictions more than a year in advance

The El Niño-Southern Oscillation (ENSO) is one of the phenomena with the greatest capacity to alter the Earth's climatic conditions. The official forecasting system currently used to issue warnings related to this phenomenon is limited, as it only anticipates ENSO by 6 to 8 months. Now, a study led by climate researchers from the Barcelona Institute for Global Health (ISGlobal), a centre supported by the ”la Caixa” Foundation, has unveiled a methodology that makes it possible to predict El Niño in real time up to 19 months in advance.

ENSO typically produces changes in global circulation patterns often linked to extreme weather events. Although it is popularly known as El Niño, this name refers only to its oceanic component, while the nomenclature Southern Oscillation refers to the associated atmospheric disruptions. “Given the large impact this phenomenon has on much of the planet, early anticipation through operational long-lead forecasts could have huge economic, societal and health benefits”, says Desislava Petrova, ISGlobal researcher and first author of the study showing the effectiveness of the new methodology in the Bulletin of the American Meteorological Society.

Over more than seven years of work, the team led by Petrova has developed, tested and improved an El Niño-Southern Oscillation statistical prediction model that incorporates carefully selected predictor variables such as subsurface and surface ocean temperature and zonal wind stress, along with additional dynamic components that account for the quasi-cyclical ENSO physics. 

Using historical data sets provided by the equatorial ocean observing system, the team tested the model to prove that it was indeed able to predict major El Niño events since the 1970s, sometimes even more than two years in advance. Then they went on to forecast in real time the development of El Niño in the equatorial areas of the Pacific in the winter of 2023/2024. The forecasting system was able to predict this moderate-to-strong warm event up to 14 months in advance, while a borderline El Niño was foreseen 19 months in advance.

Having demonstrated the operational forecasting potential of their model, and considering results from other recent ENSO prediction studies, the scientific team calls on the authorities to incorporate these early forecasting systems and increase the official lead time of operational ENSO forecasting. “It is vital to take advantage of the tremendous potential that this model has in fields as diverse as health impact studies, the epidemiology of vector-borne diseases such as dengue or malaria, or energy production systems”, says Ivana Cvijanovic, researcher at ISGlobal and the French National Research Institute for Sustainable Development (IRD) and last author of the study. 

Reference

Petrova, D., X. Rodó, S. J. Koopman, V. Tzanov, and I. Cvijanovic, 2024: The 2023/24 El Niño and the Feasibility of Long-Lead ENSO Forecasting. Bull. Amer. Meteor. Soc., 105, E1915–E1928, https://doi.org/10.1175/BAMS-D-23-0158.1.