El Niño is a natural climate phenomenon that significantly influences global weather patterns. This cyclical event involves changes in ocean temperatures and atmospheric conditions across the Pacific Ocean, leading to widespread shifts in rainfall, temperatures, and extreme weather events. The emergence of El Niño in 2023 garnered attention due to its potential to reshape climatic conditions worldwide.
Understanding El Niño
El Niño is characterized by the warming of ocean surface temperatures in the central and eastern tropical Pacific Ocean. This warming occurs when the trade winds, which blow from east to west across the Pacific, weaken or even reverse course. As these winds diminish, the warm surface water, pushed towards the western Pacific, instead spreads eastward.
This shift in warm water distribution impacts atmospheric circulation. Warmer ocean temperatures in the central and eastern Pacific lead to increased rising air and storm activity in those regions, while reducing it over areas like Indonesia. This alters global atmospheric circulation, influencing weather patterns far beyond the Pacific basin.
The Emergence of El Niño in 2023
The 2023 El Niño event began to emerge in the boreal spring of 2023, following an extended period of La Niña conditions from 2020 to 2023. Scientists observed a gradual increase in sea surface temperatures in the Gulf of California from February to July 2023. This warming was accompanied by a decrease in chlorophyll-a levels, mirroring patterns seen during the 2015 extreme El Niño event.
El Niño conditions were officially declared in June 2023, as the atmospheric response to the warmer Pacific sea surface temperatures became apparent. By mid-October 2023, the event had plateaued at a moderate strength, with sea surface temperatures in the central-eastern equatorial Pacific about 1.5°C above average. Subsurface ocean temperatures in May 2023 were the fourth-warmest on record, suggesting continued El Niño development. The event reached its strongest point between November 2023 and January 2024, with a peak value around 2.0°C above the average sea surface temperature for the eastern and central tropical Pacific.
Worldwide Effects of El Niño 2023
The 2023 El Niño contributed to significant global and regional impacts, often interacting with existing climate change trends. The year 2023 was projected to be the hottest on record, with global average temperatures reaching record highs, including July 2023 being declared the hottest month in 120,000 years, influenced by both El Niño and broader climate change.
In terms of rainfall, El Niño 2023 altered patterns across various regions. Increased rainfall and coastal flooding were observed in Ecuador, northern Peru, small island developing states, southern South America, the southern United States, central Asia, and the Horn of Africa. Conversely, severe droughts were expected in Australia, Southern Africa, Indonesia, India, and parts of southern Asia, impacting crops and livelihoods.
El Niño also influenced extreme weather events. Heatwaves and wildfires became more frequent and severe in some areas, such as Australia. The phenomenon heightened the risk of outbreaks of diseases like cholera, dengue fever, and malaria in vulnerable regions. In northern Europe, El Niño winters tend to be drier and colder, while southern Europe experiences wetter conditions.
What Happens After El Niño
El Niño events typically last between nine to twelve months and eventually transition back to neutral conditions or sometimes into a La Niña phase. This transition often sees the warm water in the eastern Pacific cool or be driven away from the equator by returning trade winds. The 2023-24 El Niño, having peaked, is gradually weakening, with a roughly 80% chance of neutral conditions developing between April and June 2024.
While there is a chance of La Niña developing later in 2024, the exact odds remain uncertain. La Niña is the opposite phase, characterized by cooler-than-average sea surface temperatures in the tropical eastern Pacific, which in turn leads to different global weather patterns. The shift from El Niño to neutral or La Niña conditions will bring new sets of temperature and precipitation patterns worldwide as the natural climate cycle continues.