The World Meteorological Organization (WMO) has indicated that 2024 is likely to become the hottest year on record, largely due to the waning cooling effects of the La Niña phenomenon, which is expected to contribute to an increase in global heat levels.
What’s La Niña?
La Niña is a climate event noted for significant cooling of sea surface temperatures in the central and eastern tropical Pacific Ocean, which leads to alterations in atmospheric conditions, including changes in wind patterns, pressure, and rainfall.
In a report issued recently in Geneva, the WMO suggested that La Niña conditions could emerge within the next three months. Long-term forecasts from the WMO’s global prediction centers estimate a 55 percent chance of transitioning from the current neutral conditions (neither El Niño nor La Niña) to La Niña conditions between December 2024 and February 2025.
The paper further anticipates a 55 percent likelihood of reverting to neutral conditions by February to April 2025.
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What is El Niño and how does it relate to La Niña?
El Niño, which serves as the counterpart to La Niña, represents a warming phase characterized by a reduction in cold water upwelling near South America, resulting in elevated sea surface temperatures throughout the Pacific and, subsequently, warmer atmospheric conditions.
Impacts of La Niña on climate
According to the WMO, La Niña generally leads to widespread cooling of sea surface temperatures in the central and eastern tropical Pacific, along with shifts in tropical atmospheric circulation. These alterations typically produce climate impacts that contrast with those associated with El Niño, especially in tropical regions.
Interplay of natural and human-induced climate change
However, the report emphasizes that natural climate phenomena like La Niña and El Niño exist within the larger framework of human-induced climate change. This overarching influence contributes to rising global temperatures, intensified extreme weather events, and modified precipitation patterns and seasonal temperatures.
Current climate conditions and predictions
The WMO pointed out that 2024 commenced under El Niño conditions and is poised to become the hottest year on record. WMO Secretary-General Celeste Saulo remarked that even with the possible emergence of La Niña, its temporary cooling effect will not counteract the warming caused by greenhouse gases that trap heat in the atmosphere.
Why are extreme weather events increasingly common?
Saulo also noted that since May, the world has witnessed an unprecedented series of extreme weather incidents, including record rainfall and flooding, which are becoming increasingly common in a changing climate, even in the absence of El Niño or La Niña conditions.
The WMO underscored the importance of seasonal forecasts for El Niño and La Niña, along with their associated global climate impacts, as vital tools for early warning and proactive response strategies.
Current data suggests that sea surface temperatures are projected to remain above average in most ocean basins, with the exception of the eastern equatorial Pacific, where weak La Niña conditions are expected. As a result, temperatures across nearly all land areas are anticipated to stay above average.
