Scientists say that while La Nina conditions could lead to slightly cooler global temperatures in 2025, the planet is still warming at an alarmingly high rate.
Last year was the warmest on record, according to European scientists, and the first in which average global temperatures exceeded the Paris Agreement target of 1.5 degrees Celsius above pre-industrial times.
The high temperatures in 2024 were driven in part by climate conditions known as El Nino (Spanish for "the boy"), according to an analysis of data by the World Meteorological Organization.
In 2025, another phenomenon known as La Nina (Spanish for “little girl”) could result in slightly cooler global temperatures, meaning the 2024 temperature record is unlikely to be broken in the year we’ve just entered. But despite this, 2025 is still likely to be among the three warmest years on record, according to the UK’s weather and climate agency, the Met Office.
What are El Nino and La Nina?
El Nino and La Nina are two opposing climates in the Pacific Ocean that affect weather around the world.
The trade winds in the Pacific tend to blow from east to west, pushing warm surface waters toward the western Pacific. El Nino occurs when these winds weaken or reverse, making the waters in the eastern Pacific—off the coast of the Americas—warmer than normal.
During La Nina periods, east-to-west trade winds become stronger, pushing warm waters further west toward the coasts of Australia and Southeast Asia. This causes cold water to “lift” or rise from the ocean floor, making sea surface temperatures lower on average, especially in the Americas.
Both El Nino and La Nina can affect weather around the world. Although each episode is different, La Nina is associated with wetter-than-normal conditions in some parts of the world, such as northern Australia, southeast Africa, and northern Brazil. It can also increase the likelihood of flooding in some regions and cause a more intense hurricane season.
What do scientists predict for 2025?
The World Meteorological Organization (WMO) says La Nina conditions could occur between November 2024 and February 2025. But its cooling effect on global temperatures could be "weak and short-lived," the IMO said.
"Since June 2023, we have seen a prolonged series of exceptional global land and sea temperatures. Even if there is a short-term cooling in La Nina, this will not change the long-term trajectory of global temperature increases due to greenhouse gases that trap heat in the atmosphere," said WMO Secretary-General Celeste Saulo.
In fact, meteorologists say that temperature predictions for 2025 are unusually high given the possibility of La Nina conditions.
"Years like 2025 that are not dominated by the El Nino warming effect should be cooler. 2016 was an El Nino year and at that time it was the warmest year on record for global temperature. However, compared to our 2025 forecast, 2016 is definitely looking good now," said Professor Adam Scaife, who leads the UK Met Office's global forecast for 2025.
The Paris Agreement has not (yet) been violated
Temperatures in 2024 appear likely to exceed 1.5 degrees Celsius above pre-industrial times for the first time, a benchmark first set by the 2015 Paris climate agreement.
But exceeding this threshold for one year is not considered a breach of the Paris threshold. Scientists say this threshold must be exceeded persistently, over a period of 20-30 years.
Some scientists say the link between climate change and the La Nina and El Nino phenomena is not entirely clear.