Despite the tropical Pacific cooling due to a La Niña weather pattern, a trend of record-breaking global temperatures has persisted.

According to the Copernicus Climate Change Service, last month’s air and surface temperatures were 1.75 degrees Celsius warmer than preindustrial levels, making it the warmest January on record.

Australia’s eastern region experienced wetter-than-normal conditions, while other regions experienced drier-than-normal conditions, according to the EU-funded Earth observation program.

“January 2025 is another surprising month, continuing the record temperatures observed throughout the last two years, despite the development of La Niña conditions in the tropical Pacific and their temporary cooling effect on global temperatures. Copernicus will continue to closely monitor ocean temperatures and their influence on our evolving climate throughout 2025.” – Samantha Burgess, Strategic Lead for Climate at ECMWF

Global-average surface air temperature anomalies relative to the 1850–1900 pre-industrial reference period for each January, all months, and running 12-month averages from 1979 to 2024. Data source: ERA5. Credit: C3S/ECMWF.

For the 19th consecutive month, January saw global-average surface temperatures surpass the 1.5C preindustrial threshold for the 18th time. World leaders pledged to try to keep global temperatures from rising by more than 1.5C under the Paris Climate Agreement, but the cutoff was based on long-term multidecadal warming rather than monthly temperatures.

After a warming El Niño event peaked in January 2024 and conditions changed to an opposing, cooling La Niña phase, climate scientists had anticipated that this exceptional spell would end.

However, the heat has persisted at record or nearly record levels, raising questions about what additional factors might be pushing it above expectations.

“This is what makes it a bit of a surprise: you’re not seeing this cooling effect, or temporary brake at least, on the global temperature that we were expecting to see,” Copernicus climate scientist Julien Nicolas told Agence France-Presse.

European-mean surface air temperature anomalies relative to 1991-2020 averaged over European land for each January, all months, and running 12-month averages from 1979 to 2025. Data source: ERA5. Credit: C3S/ECMWF.

Copernicus stated that current temperatures in areas of the equatorial Pacific Ocean indicated a slowing or stalling of the move towards the cooling phenomenon, and that La Niña is predicted to be weak. According to Nicolas, it might vanish by March.

Copernicus announced last month that the average global temperature for 2023 and 2024 had risen above 1.5C for the first time. Although this did not constitute a permanent violation of the Paris Climate Accord’s long-term 1.5C target, it was an obvious indication that the limit was being pushed.

Extreme weather events like heatwaves, droughts, and heavy rainfall become more frequent and intense with each degree of warming above 1.5C.

According to Copernicus, Arctic sea ice reached a monthly record low in January. It was the second-lowest in that dataset, according to analysis released this week from the US. Overall, scientists predict that 2025 will be the third-hottest year on record, meaning it won’t be remembered as the next 2023 or 2024.

Surface air temperature anomaly for January 2025 relative to the January average for the period 1991-2020. Data source: ERA5. Credit: C3S/ECMWF.  ​​​​

Copernicus, plans to keep a careful eye on ocean temperatures to look for clues about potential climate behavior. Cooler waters can absorb more heat from the atmosphere, lowering air temperatures. Oceans are a key carbon sink and climate regulator. Additionally, 90% of the excess heat trapped by greenhouse gas emissions from human activity is stored there.

Nicolas said: “This heat is bound to resurface periodically. I think that’s also one of the questions: is this what has been happening over the past couple of years?”

Sea-surface temperatures were exceptionally warm in 2023 and 2024, and Copernicus said readings in January were the second highest on record. “That is the thing that is a little puzzling – why they remain so warm,” Nicolas said.

All scientists agree that long-term global warming has been caused by the burning of fossil fuels, and that annual temperature variations can also be caused by natural climate variability.

However, El Niño and other natural warming cycles were insufficient to account for the changes in the atmosphere and seas, and other sources of information were being looked for.

According to one theory, the global switch to cleaner shipping fuels in 2020 sped up global warming by lowering sulfur emissions, which cause clouds to reflect sunlight more reflectedly and resemble mirrors.

Another peer-reviewed study examined whether the Earth’s surface had been able to absorb more heat due to a decrease in low-lying clouds in December. “It’s still up for debate,” Nicolas stated.

To help with its calculations, the EU monitor uses billions of measurements from weather stations, ships, airplanes, and satellites. Although its records date back to 1940, scientists can use evidence from much earlier periods to support their conclusions thanks to other sources of climate data, including ice cores, tree rings, and coral skeletons.

According to scientists, the current epoch is probably the warmest the planet has experienced in 125,000 years.

Related Unexpectedly, January 2025 was Earth’s hottest January on record – January had not been expected to set a new record because of cool waters in the Eastern Pacific from a weak La Niña event.