THE world was warmed to yet another monthly record temperature in January, despite a cooling La Nina and predictions of a slightly less hot 2025, according to the European climate service Copernicus.

The surprising January heat record coincides with a new study by former top Nasa scientist James Hansen and others arguing that global warming is accelerating. It’s a claim that’s dividing the research community.

January 2025 globally was 0.09°C warmer than January 2024, the previous hottest January, and was 1.75°C warmer than it was before industrial times, Copernicus calculated. 

It was the 18th month of the last 19 that the world hit or passed the internationally agreed upon warming limit of 1.5°C above pre-industrial times. 

Scientists won’t regard the limit as breached unless and until global temperatures stay above it for 20 years. But many scientists say this era is the warmest in about 120,000 years or since the start of human civilisation.

By far the biggest driver of record heat is greenhouse gas build up from the burning of coal, oil and natural gas, but the natural contributions to temperature change have not been acting quite as expected, said Samantha Burgess, strategic lead for climate for the European weather agency.

The big natural factor in global temperatures is usually the natural cycle of changes in the equatorial Pacific Ocean waters. 

Last year was a substantial El Nino, though it ended last June and the year was even warmer than initially expected, the hottest on record.

El Nino’s cooler flip side, a La Nina, tends to dampen the effects of global warming, making record temperatures far less likely. 

A La Nina started in January after brewing for months. Just last month, climate scientists were predicting that 2025 wouldn’t be as hot as 2024 or 2023, with the La Nina being a major reason.

“Even though the equatorial Pacific isn’t creating conditions that are warming for our global climate, we’re still seeing record temperatures,” Ms Burgess said, saying much of that is because of record warmth in the rest of the world’s oceans.

Usually after an El Nino like last year, temperatures fall rapidly, but “we’ve not seen that,” Ms Burgess told reporters.

University of Michigan environment dean Jonathan Overpeck said: “There seems little doubt that global warming and the impacts of climate change are accelerating.”