Climate network and complexity approach predict neutral ENSO event for 2025

TL;DR

This study applies climate network and complexity methods to forecast a neutral ENSO event in 2025, suggesting a likely decrease in global temperatures compared to 2024, with high forecast confidence.

Contribution

The paper introduces two novel approaches for early ENSO forecasting and combines them with statistical methods to predict the 2025 ENSO state.

Findings

Both methods forecast a neutral ENSO in 2025 with over 91% probability.

The combined forecast indicates a 69.6% chance of a neutral ENSO event in 2025/26.

There is a 21.8% probability of La Niña occurring in 2025.

Abstract

The El Ni\~no Southern Oscillation (ENSO) is the strongest driver of interannual global climate variability and can lead to extreme weather events like droughts and flooding. Additionally, ENSO influences the mean global temperature with strong El Ni\~no events often leading, in a warming climate, to new record highs. Recently, we have developed two approaches for the early forecasting of El Ni\~no. The climate network-based approach allows forecasting the onset of an El Ni\~no event about 1 year ahead. The complexity-based approach allows additionally to forecast the magnitude of an upcoming El Ni\~no event in the calendar year before. These methods successfully forecasted the onset of an Eastern Pacific El Ni\~no for 2023/24 and the subsequent record-breaking warming of 2024. Here, we apply these methods to forecast the ENSO state in 2025. Both methods forecast the absence of an El Ni\~no in 2025, with 91.2% and 91.7% probability, respectively. Combining these forecasts with a logistic regression based on the Oceanic Ni\~no Index (ONI) leads to a 69.6% probability that 2025/26 will be a neutral ENSO event. We estimate the probability of a La Ni\~na at 21.8%. This makes it likely that the mean global temperature in 2025 will decrease somewhat compared to the 2024 level.