Geneva: The world edged closer to a dangerous climate threshold in 2025, with new data showing the planet experienced its third warmest year on record and, for the first time, a three-year period (2023-2025) of global temperatures rising above the critical 1.5°C warming limit.
The consolidated three-year average 2023-2025 temperature is 1.48 °C (with a margin of uncertainty of ± 0.13 °C) above the pre-industrial era. The past eleven years, 2015-2025, are the eleven warmest years.
The news data also showed that 2025 was the third warmest year on record only marginally (0.01°C) cooler than 2023, and 0.13°C cooler than 2024, the warmest year on record.
This marks the first time a three-year period has exceeded the 1.5°C limit. Air temperature over global land areas was second warmest, whilst the Antarctic saw its warmest annual temperature on record and the Arctic its 2nd warmest, showed the data.
The findings are released by the European Centre for Medium-Range Weather Forecasts (ECMWF), which operates the Copernicus Climate Change Service (C3S) and Copernicus Atmosphere Monitoring Service (CAMS) on behalf of the European Commission.
The following organisations involved in global climate monitoring, ECMWF, NASA, NOAA, the UK Met Office, Berkeley Earth, and the World Meteorological Organisation (WMO) – have coordinated the release of their data.
“The year 2025 started and ended with a cooling La Niña and yet it was still one of the warmest years on record globally because of the accumulation of heat-trapping greenhouse gases in our atmosphere. High land and ocean temperatures helped fuel extreme weather – heatwaves, heavy rainfall and intense tropical cyclones, underlining the vital need for early warning systems,” said WMO Secretary-General Celeste Saulo.
A separate study published in Advances in Atmospheric Sciences said that ocean temperatures were also among the highest on record in 2025, reflecting the long-term accumulation of heat within the climate system.
About 90% of excess heat from global warming is stored in the ocean, making ocean heat a critical indicator of climate change.
From 2024-2025, the global upper 2000 m ocean heat content (OHC) increased by ∼23 ± 8 Zettajoules relative to 2024, according to the study led by Lijing Cheng with the Institute of Atmospheric Physics at the Chinese Academy of Sciences.
Regionally, about 33% of the global ocean area ranked among its historical (1958–2025) top three warmest conditions, while about 57% fell within the top five, including the tropical and South Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and Southern Oceans, underscoring the broad ocean warming across basins.
The study found the global annual mean sea surface temperature (SST) in 2025 was 0.49 °C above the 1981–2010 baseline and 0.12 ± 0.03 °C lower than in 2024, consistent with the development of La Niña conditions, but still ranking.
Rising concentrations of greenhouse gases in the atmosphere, mainly a direct consequence of human activities – are the primary driver of the observed long-term increase in the global mean temperature
Laurence Rouil, Director of Copernicus Atmosphere Monitoring Service at ECMWF said, Atmospheric data from 2025 paints a clear picture: human activity remains the dominant driver of the exceptional temperatures we are observing.
“Atmospheric greenhouse gases have steadily increased over the last 10 years. We will continue to track greenhouse gases, aerosols, and other atmospheric indicators to help decision makers understand the risks of continuing emissions and respond effectively, reinforcing synergies between air quality and climate policies. The atmosphere is sending us a message, and we must listen” he said.
