The organization warns that 1.5ºC of global warming could be reached by the end of this decade.
2025 was the third warmest year on record, only slightly (0.01°C) cooler than 2023 and 0.13°C cooler than 2024, which remains the warmest year in the series. The average temperature in 2025 was 14.97°C, a total of 0.59°C above the 1991-2020 average and 0.13°C below 2024.
These are some of the conclusions of ‘Global Climate Highlights’, the report published this Wednesday by the European Centre for Medium-Range Weather Forecasts (ECMWF), which manages the Copernicus Climate Change Service (C3S) and the Copernicus Atmosphere Monitoring Service (CAMS) on behalf of the European Commission.
In the report, the organization details that January 2025 was the warmest January on record globally, and that March, April, and May were the second warmest for that time of year. In fact, all months of the year except February and December were warmer than the corresponding month of any year prior to 2023.
More generally, it notes that the average air temperature in 2025 was 1.47ºC higher than the pre-industrial level (i.e., that recorded between 1850 and 1900), making it the second warmest in the series. Based on various methods, the ECMWF indicates that the current level of long-term global warming is estimated at around 1.4ºC above the pre-industrial level. “According to the current rate of warming, the 1.5°C limit of the Paris Agreement for long-term global warming could be reached by the end of this decade, more than a decade earlier than anticipated,” it warned.
In total, the agency indicates that half of the world’s land surface experienced more days than usual with intense heat stress during 2025, defined as a perceived temperature of 32°C or higher. In areas with dry and often windy conditions, high temperatures also contributed to the spread and intensification of exceptional wildfires, which in turn produced carbon and toxic air pollutants.
The report indicates that this was the case in North America and parts of Europe (which, in fact, experienced their highest total annual emissions from wildfires). “These emissions significantly degraded air quality and had potentially harmful effects on human health, both locally and on a larger scale,” it emphasized.
ANTARCTICA RECORDED ITS WARMEST ANNUAL TEMPERATURE
Among other things, it also specifies that the extrapolated global sea surface temperature was 20.73°C, the third warmest after 2024 and 2023; and that Antarctica recorded its warmest annual temperature ever measured, while the Arctic recorded its second warmest.
It also specifies that in February 2025, the combined sea ice coverage of both poles fell to its lowest value since at least the beginning of satellite observations in the late 1970s.
In the Arctic, the monthly sea ice extent was the lowest on record for the time of year in January, February, March, and December, and the second lowest in June and October. In the Antarctic, the monthly extent reached its fourth lowest annual minimum in February and its third lowest annual maximum in September. THE FIRST THREE-YEAR PERIOD ABOVE 1.5ºC
The organization indicates that global temperatures over the past three years (2023-2025) averaged more than 1.5°C above pre-industrial levels, making this the first three-year period to exceed this limit. According to the ECMWF, this period—2023, 2024, and 2025—was exceptionally warm due to the accumulation of greenhouse gases (GHGs) in the atmosphere and the exceptionally high sea surface temperatures.
On the one hand, it clarifies that the accumulation of GHGs in the atmosphere was due to continued emissions and the reduced absorption of carbon dioxide (CO2) by natural sinks. On the other hand, it attributes the sea surface temperature to an El Niño event and other factors of oceanic variability, which it says were amplified by climate change.
“Other additional factors include changes in the amounts of aerosols and low clouds, and variations in atmospheric circulation,” it added.
According to Laurence Rouil, director of the Copernicus Atmosphere Monitoring Service at the ECMWF, the atmospheric data from 2025 present a “clear” picture, indicating that human activity remains the dominant factor behind the exceptional temperatures observed. She also emphasizes that atmospheric greenhouse gas concentrations have increased steadily over the past ten years.
“We will continue to monitor greenhouse gases, aerosols, and other atmospheric indicators to help decision-makers understand the risks of continued emissions and respond effectively, strengthening the synergies between air quality and climate policies. The atmosphere is sending us a message, and we must listen,” she stated.
