Improved El Niño forecasting by cooperativity detection

TLDR

El Niño, a warming of the eastern equatorial Pacific that can cause global damage, is currently forecastable only about six months ahead, but evidence shows a large‑scale cooperative mode linking the basin to the rest of the ocean develops a year before the event. The study aims to extend El Niño prewarning to 12 months, doubling the early‑warning period to mitigate severe impacts such as crop failures in developing nations. Using network analysis of teleconnections in high‑quality observations since 1950, the authors construct a 12‑month forecasting scheme that achieves hit rates above 0.5 and false‑alarm rates below 0.1. The approach achieves hit rates exceeding 0.5 with false‑alarm rates below 0.1.

Abstract

Although anomalous episodic warming of the eastern equatorial Pacific, dubbed El Niño by Peruvian fishermen, has major (and occasionally devastating) impacts around the globe, robust forecasting is still limited to about 6 mo ahead. A significant extension of the prewarning time would be instrumental for avoiding some of the worst damages such as harvest failures in developing countries. Here we introduce a unique avenue toward El Niño prediction based on network methods, inspecting emerging teleconnections. Our approach starts from the evidence that a large-scale cooperative mode—linking the El Niño basin (equatorial Pacific corridor) and the rest of the ocean—builds up in the calendar year before the warming event. On this basis, we can develop an efficient 12-mo forecasting scheme, i.e., achieve some doubling of the early-warning period. Our method is based on high-quality observational data available since 1950 and yields hit rates above 0.5, whereas false-alarm rates are below 0.1.