January 2025 has officially set a new record as the warmest January ever, with global temperatures soaring 1.75°C above pre-industrial levels. This unexpected anomaly comes despite the presence of La Niña, a climate phenomenon typically associated with cooler global temperatures.
According to data from the ERA5 dataset, analyzed by climate scientists, the past month witnessed unusually high temperatures across both hemispheres. Records were shattered in Jamaica and Madagascar on January 31, highlighting the global scale of the warming trend.
A Record-Breaking Start to 2025
The European Centre for Medium-Range Weather Forecasts (ECMWF), which oversees the Copernicus Climate Change Service (C3S), confirmed that January 2025 surpassed the previous records set in 2024, 2020, and 2016 all of which occurred during El Niño years.
El Niño, the warm phase of the El Niño-Southern Oscillation (ENSO), has historically driven record-high temperatures. However, this time, La Niña a cooling phase that started in December 2024 was expected to temper global temperatures. Instead, Earth’s warming trend has continued unabated.
“This is despite the presence of La Niña conditions in the tropical Pacific, with the El Niño event of 2023–2024 long faded,” noted Zeke Hausfather, a climate scientist at Berkeley Earth.
The 2023–2024 El Niño played a key role in making 2024 the hottest year ever recorded, with an annual temperature anomaly of 1.55°C above pre-industrial levels, surpassing the critical 1.5°C threshold set by the Paris Agreement. The La Niña phase was anticipated to bring a cooling effect in 2025, but the latest data challenges that expectation.
Climate Cycles No Longer in Control?
The National Oceanic and Atmospheric Administration (NOAA) expects this La Niña event to be short-lived, lasting only until April 2025 unlike the prolonged 2020–2023 La Niña, which still saw extreme heat waves despite its cooling influence.
The World Meteorological Organization (WMO) had already cautioned in December 2024 that rising greenhouse gas emissions might override La Niña’s expected cooling effect. Scientists now believe Earth’s natural climate cycles are being increasingly overshadowed and even altered by human-induced warming.
Hausfather, analyzing the broader climate picture”Both 2023 and 2024 were exceptionally warm years, with 2024 surpassing the 1.5°C threshold. While many expected 2025 to be cooler, the record-breaking January suggests otherwise.”
This is the first time that a January during La Niña has been warmer than the surrounding El Niño or ENSO-neutral years.
What Lies Ahead?
If this trend continues, 2025 could turn out warmer than previously anticipated, contradicting projections of a temporary cooling phase. Scientists are now working to understand the full set of factors driving this unexpected warmth.
With global temperatures already at historic highs, the start of 2025 signals that the fight against climate change is far from over.
