The UN's weather agency, the World Meteorological Organization (WMO), warned on Wednesday that the return of the El Nino climate pattern later this year is highly likely.
The naturally occurring phenomenon is associated with increased temperatures that could drive up the extreme heat records seen in recent years.
The WMO put the probability of El Nino occurring by the end of July at 60% and by the end of September at 80%.
"This will change the weather and climate patterns worldwide," WMO official Wilfran Moufouma Okia told reporters in Geneva.
End of La Nina cooling period
The warming effects of El Nino last occurred from 2018 to 2019, but there has been a long cooling period, known as La Nina, since 2020.
Despite this cooling period, the last eight years have been the warmest on record thanks to manmade climate change. The WMO has now warned the world to prepare for even warmer temperatures as El Nino begins to kick in.
La Nina "acted as a temporary brake on global temperature increase," WMO chief Petteri Taalas said in a statement.
Now "the world should prepare for the development of El Nino." The expected arrival of the climate pattern "will most likely lead to a new spike in global heating and increase the chance of breaking temperature records."
What will be the impact of El Nino?
Experts were not yet able to predict how long or how strong El Nino will be this time around.
The previous occurrence was considered relatively weak, but the one before that, from 2014 to 2016, was one of the strongest on record.
2016 was "the warmest year on record because of the 'double whammy' of a very powerful El Nino event and human-induced warming from greenhouse gases," the WMO said.
El Nino can also come on slowly, and the effect on global temperatures tends to be most obvious a year after it emerges, so the worst impacts may be seen first in 2024.
The climate pattern often brings increased rainfall to certain areas such as southern South America, central Asia and the Horn of Africa — leading to hopes it may bring an end to an ongoing drought there.
But it is also associated with an increased risk of droughts in other areas such as Australia, Indonesia and parts of southern Asia.
Taalas called for early warning systems amid fears El Nino could "also trigger more extreme weather and climate events."
