Scientists report that the La Niña phenomenon is emerging, resulting in cooler ocean surface temperatures, with a 60% likelihood of occurrence between July and September.
The return of the cool La Niña weather phenomenon this year is expected to help reduce temperatures somewhat after several months of record global heat. This impact may be felt in the coming months as the warm El Niño weather pattern— which has driven global temperature increases and extreme weather worldwide since mid-2023—shows signs of ending, according to the World Meteorological Organization (WMO) of the United Nations (UN) on June 3.
La Niña can cause heavy rainfall in some areas and drought in others. (Photo: Somchai Poomlard)
While El Niño warms ocean surfaces, La Niña represents a cooling of ocean surface temperatures over vast areas of the tropical Pacific, accompanied by winds, rainfall, and changes in atmospheric pressure. In many regions, especially the tropics, La Niña brings climate impacts that are opposite to those of El Niño, resulting in drought in some areas and heavy rainfall in others.
The WMO indicated that there is a 60% chance of La Niña occurring from July to September, and a 70% chance from August to November. The likelihood of El Niño re-emerging is very low.
The majority of the excess heat on Earth due to climate change is stored in the oceans. In the United States, the National Oceanic and Atmospheric Administration (NOAA) has factored La Niña into its Atlantic hurricane season forecasts for this year. According to NOAA, 4 to 7 strong hurricanes are expected in the Atlantic from June to November.
“The upcoming Atlantic hurricane season is expected to be more active than normal due to a combination of factors, including ocean temperatures near record highs in the Atlantic, the development of La Niña in the Pacific, Atlantic trade winds, and diminished wind shear,” NOAA stated.
However, the WMO warns that global temperatures will continue to rise in the long term due to human-induced climate change. This will exacerbate extreme weather events and disrupt seasonal temperature and rainfall patterns.
Every month since June 2023, when El Niño was active, has set new high-temperature records. As of now, 2023 is also the warmest year ever recorded globally.
“The end of El Niño does not mean that long-term climate change will cease, as the planet will continue to warm due to greenhouse gases trapping heat. High sea surface temperatures will still play a significant role in the coming months,” emphasized Ko Barrett, Deputy Secretary-General at the WMO.
The past nine years have been the warmest on record, even during the cooling effects of the La Niña event that lasted from 2020 to early 2023, according to the WMO. The most recent El Niño peaked in December last year and is one of the five strongest on record.
