Introduction

Abstract

Even if they cannot readily recall its exact definition or its particular historical impacts, governments, media outlets, communities, and weather-sensitive economic sectors are for the most part aware of El Niño as a potential threat to society. The quasi-periodic oceanic extreme is no longer the unexplained phenomenon that it was as recently as the late 1960s, when it was first determined to be a tropical Pacific Ocean basin-wide event (Bjerknes 1969).

Since that time, El Niño has come to be commonly viewed as another expression of climate variability on a sub-decadal scale, much as is the flow of the seasons at the annual scale. As with seasonal flows, El Niño, though more irregular in its timing, provides close observers who have been forewarned about its aperiodic onset and likely impacts with a degree of forecast reliability. To be sure, El Niño today almost invariably appears in media headlines as a red flag in countries at risk of the hydrometeorological hazards each event is known to produce. At this point, social media is also abuzz with concern when an El Niño forms, especially with regard to its impacts.

El Niños always yield new social and physical scientific research findings that provide insights for policymakers. They also tend to expose societal strengths and weaknesses and afford lessons for decision makers on how better to prepare for and respond to future event forecasts, impacts, and recovery efforts. Additionally, being adequately prepared for the extremes of the El Niño Southern Oscillation (ENSO), which are marked by anomalously warm or cold sea surface temperatures (SSTs) in the tropical Pacific, will benefit societal coping capabilities within a warming global climate, especially in terms of the variability and extremes that are predicted to accompany an altered climate regime.