The cooling La Nina phenomenon in the equatorial Pacific Ocean may develop in the next three months but it is likely to be weak and short-lived, according to the latest update from the World Meteorological Organization (WMO) on December 11, 2024.
La Nina is a phase of the El Nino Southern Oscillation (ENSO) when cooler-than-normal temperatures prevail over the central and eastern equatorial Pacific Ocean and there is a temporary cooling effect on global average temperatures.
A weak and short-lived La Nina may mean the heightened trend of global average temperatures in 2023 and 2024 may not relent in 2025 as well. The year 2024 is already on its way to be hottest on record with a global average annual temperature anomaly crossing 1.5°C since the pre-industrial period for the first time.
There is a 55 per cent chance of the development of the La Nina between December and February, according to the WMO. Then there is a 55 per cent chance of return to ENSO neutral conditions when the equatorial Pacific Ocean has neither El Nino (warmer-than-normal phase) nor La Nina.
However, naturally occurring climate events such as La Nina and El Nino events are taking place in the broader context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather and climate, and impacting seasonal rainfall and temperature patterns, according to the WMO.
“The year 2024 started out with El Nino and is on track to be the hottest on record. Even if a La Nina event does emerge, its short-term cooling impact will be insufficient to counterbalance the warming effect of record heat-trapping greenhouse gases (GHG) in the atmosphere,” said Celeste Saulo, secretary general of the WMO.
“Even in the absence of El Nino or La Nina conditions since May, we have witnessed an extraordinary series of extreme weather events, including record-breaking rainfall and flooding which have unfortunately become the new norm in our changing climate,” said Saulo.
For instance, hurricanes in the North Atlantic Ocean and typhoons in the Northwest Pacific Ocean have seen record breaking trends in rapid intensification, amount of rainfall and wind speeds which have been tied to the excessive warming of the atmosphere and oceans by climate scientists.
In many places around the world, even autumn and wintertime temperatures have been much higher-than-normal in November and those trends have continued into December. Both maximum and minimum temperature records have broken in regions such as Southeast Asia, the Caribbean Islands, South and West Asia.
For instance, in Southeast Asia, Indonesia has been suffering from much higher-than-normal minimum or nighttime temperatures. Just on December 11, Belitung Island had its hottest night in history with a minimum temperature of 26.8°C.
The area crossed a minimum temperature of 26°C for the first time in recorded history, according to M Herrera, climatologist and weather historian on social media platform X.
In South Asia, many areas along the western Indian coast have also witnessed record breaking nighttime temperatures. The India Meteorological Department (IMD) has also predicted a warmer-than-normal winter season (December to February) for most of the country.
This trend of warm temperatures, even during winters, is disturbing and shows the impact of the background warming to emissions of GHGs from human emissions, especially from the burning of fossil fuels.
October 2024 was also the second-hottest October on record after October 2023, according to the National Oceanic and Atmospheric Administration (NOAA). November 2024 was the second-hottest on record after November 2023, according to the European Union’s Copernicus Climate Change Service (C3S).
Overall, 2024 may overtake the annual warming of 2023 and become the hottest year on record.