Despite a cold winter in the U.S. and the arrival of La Niña, January 2025 became the hottest January ever, according to Copernicus, the European climate service. Scientists had expected temperatures to drop slightly this year, but the data tells a different story.
January 2025 Was Hotter Than Ever
Copernicus reported that January 2025 was 0.09°C warmer than January 2024, the previous record-holder. It was also 1.75°C hotter than pre-industrial levels.
For 18 out of the last 19 months, global temperatures have touched or exceeded the 1.5°C warming limit set by international agreements. However, scientists will only consider this limit officially breached if global temperatures remain above it for 20 consecutive years.
Earth Is Experiencing Unprecedented Heat
Copernicus began keeping records in 1940, while U.S. and British records date back to 1850. But scientists studying tree rings and other natural indicators say the planet has not been this warm in 120,000 years—spanning the entire history of human civilization.
Greenhouse Gases Are Driving Extreme Heat
The biggest factor behind this record-breaking heat is greenhouse gas emissions from burning coal, oil, and gas, said Samantha Burgess, a climate expert at the European weather agency.
Natural climate cycles also influence global temperatures. Last year’s El Niño—a warming event in the Pacific Ocean—pushed temperatures to record highs. Normally, its cooler counterpart, La Niña, helps lower global temperatures. However, despite La Niña starting in January 2025, temperatures remain high.
Burgess explained, “Even though the equatorial Pacific isn’t creating conditions that are warming for our global climate, we’re still seeing record temperatures.” She pointed to unusually warm oceans worldwide as a major reason.
U.S. Cold Snap vs. Global Heat
Many Americans might find it hard to believe that January was the hottest ever, given the freezing temperatures in the U.S.. However, Burgess clarified that the U.S. is only a small part of the world, while other regions experienced extreme heat.
For example, the Canadian Arctic saw temperatures 30°C above normal, causing unexpected sea ice melting. Copernicus reported that Arctic sea ice reached record-low levels, tying with previous lows. Meanwhile, the U.S. National Snow and Ice Data Center ranked it as the second-lowest January on record, behind 2018.
Could 2025 Break More Records?
February 2025 started slightly cooler than last year, but experts warn that this year could still challenge 2024 as the hottest ever.
James Hansen, a former NASA scientist known as the “godfather of climate science,” co-authored a study in the journal Environment: Science and Policy for Sustainable Development. He and his team found that global temperatures over the past 15 years have risen twice as fast as in the previous 40 years.
Hansen told The Associated Press, “I’m confident that this higher rate will continue for at least several years. Over the full year, it’s going to be nip-and-tuck between 2024 and 2025.”
He also pointed to new shipping regulations that have reduced sulfur pollution, which previously helped reflect sunlight away from Earth. With less pollution blocking sunlight, he expects warming to continue.
Scientists Disagree on Climate Acceleration
Not all experts agree that global warming is speeding up.
Jonathan Overpeck, an environmental scientist at the University of Michigan, said the situation is alarming: “The persistence of record warmth through 2023, 2024, and now into the first month of 2025 is jarring to say the least. There seems little doubt that global warming and the impacts of climate change are accelerating.”
However, Gabe Vecchi of Princeton University and Michael Mann from the University of Pennsylvania disagree.
Vecchi argued that recent temperature spikes could be random. Mann added that warming remains within the predictions of climate models, meaning it might not indicate sudden acceleration.
What’s Next?
With record-high ocean temperatures, continued greenhouse gas emissions, and an uncertain climate pattern, experts remain divided. However, one thing is clear—global temperatures have reached unprecedented levels, and 2025 could be another landmark year for climate records.