December 18th, 2024
The World Meteorological Organization (WMO) reported earlier this month that the 2023-24 El Niño event, one of the five strongest on record, is gradually weakening. Despite this, its impact on global climate, compounded by the heat trapped by greenhouse gases from human activities, is expected to continue in the coming months, with above-normal temperatures predicted over almost all land areas between March and May.
The big picture: El Niño, a naturally occurring climate pattern characterised by the warming of ocean surface waters in the central and eastern tropical Pacific Ocean, has a significant influence on weather and storm patterns around the globe. Occurring on average every two to seven years, El Niño events typically last nine to 12 months but occur against the backdrop of a climate that is being altered by human activities.
2023: A record year for heat: "Every month since June 2023 has set a new monthly temperature record – and 2023 was by far the warmest year on record," stated WMO Secretary-General Celeste Saulo. She attributed these record temperatures to both El Niño and the unequivocal effect of heat-trapping greenhouse gases.
Ocean temperatures: The equatorial Pacific's surface temperatures clearly indicate El Niño's presence. However, sea surface temperatures in other global parts have also been unusually high for the past 10 months. January 2024 saw the highest sea-surface temperature on record for January, a phenomenon that cannot be explained by El Niño alone.
Looking ahead: While El Niño is expected to weaken, with a 60% chance of persisting during March-May and an 80% chance of transitioning to neutral conditions (neither El Niño nor La Niña) from April to June, it may still significantly influence global climate patterns. There's a possibility of La Niña developing later in the year, though the odds remain uncertain.
Impact on global climate: Despite the weakening El Niño, above-normal sea-surface temperatures across much of the global oceans are anticipated to lead to above-normal land temperatures over the next three months. This will influence regional rainfall patterns, according to the Global Seasonal Climate Update issued by WMO.
Early warnings save lives: The current El Niño event, which developed in June 2023 and peaked between November and January, underscores the importance of accurate seasonal forecasts and early warnings in saving lives and protecting livelihoods. The WMO's updates play a crucial role in enabling governments, humanitarian agencies, and decision-makers to prepare and respond effectively to climate-related challenges.
Global Seasonal Climate Update: Alongside the ENSO Update, WMO now issues regular Global Seasonal Climate Updates, incorporating the influences of other climate phenomena such as the North Atlantic Oscillation and the Indian Ocean Dipole. These updates predict temperature anomalies and rainfall patterns, offering vital information for preparation and response efforts worldwide.
National monitoring: National Meteorological and Hydrological Services (NMHSs) will continue to monitor the situation closely, providing updated outlooks on El Niño's dissipation and the potential development of La Niña. Given the typical uncertainty in long-lead forecasts during the boreal spring and early summer, these updates are essential for accurate and timely climate predictions.