Ellen Phiddian
Cosmos science journalist
International monitoring bodies have confirmed 2024 as the warmest year on record, beating 2023 as the previous record-holder.
The record was confirmed by 7 organisations: the World Meteorological Organization, the European Union’s Copernicus Climate Change Service, the European Centre for Medium-Range Weather Forecasts, the UK’s Met Office, the USA’s NASA and National Oceanic and Atmospheric Administration, and US-based independent organisation Berkeley Earth.
Each of these organisations runs separate analyses on global temperatures, using satellite data, temperature records, and other climate indicators.
It was also the first calendar year that global temperatures were 1.5°C above pre-industrial levels, according to most of the bodies.
This does not mean the Paris Agreement, which sets 1.5°C as a lower threshold for limiting global warming, has been breached – yet. The Agreement relies on decade-long averages, not individual years.
Most of the agencies also pointed out that each of the past 10 years, from 2015-2024, was one of the 10 warmest years on record.
Because of differing datasets and baselines, each organisation has different numbers for 2024’s temperatures. Copernicus, for instance, found that global average temperatures were 1.60°C above 1850-1900 levels, while NASA found levels were 1.47°C higher and the WMO found levels were 1.55°C higher.
“Climate history is playing out before our eyes,” says Celeste Saulo, Secretary-General of the WMO.
“We’ve had not just one or two record-breaking years, but a full 10-year series. This has been accompanied by devastating and extreme weather, rising sea levels and melting ice, all powered by record-breaking greenhouse gas levels due to human activities.”
“Between record breaking temperatures and wildfires currently threatening our centres and workforce in California, it has never been more important to understand our changing planet,” says NASA Administrator Bill Nelson.
While the past decade has had the 10 warmest years, both 2024 and 2023 have been significantly warmer than the previous 8.
Berkeley Earth states that this “warming spike” has been caused by multiple things, some of which are not yet fully explained. Anthropogenic climate change, and a warmer El Niño phase in the Pacific Ocean, have both played a role, and the organisation suggests that a reduction in aerosol pollution could also have had an influence.
“Superimposed on the long-term trend are small ups and downs that typically last a year or two and arise mostly from natural variability,” says Professor Tim Osborn, director of the climate research unit at the UK’s University of East Anglia, which works with the UK Met Office to provide their results.
“These small variations of 0.1-0.2°C can temporarily push the global temperature above or below its underlying warming trend and make an individual year such as 2024 exceed 1.5°C even though the underlying warming has not quite reached that level yet.”
While 2025 may not be the hottest year on record again, with El Niño Southern Oscillation patterns trending cooler, it will likely be close to the hottest, according to the UK’s Met Office.
“The world as a whole has not yet begun to reduce its use of fossil gas, oil and coal, so emissions of CO2 have not yet peaked and as a result the global temperature continues to rise as predicted by climate scientists,” says Osborn.
