Last year was among the three warmest ever recorded on the planet, the World Meteorological Organization (WMO) said, while European Union scientists confirmed that average temperatures have exceeded the 1,5 degrees Celsius threshold for global warming for the first time, and for the longest time since records began.
The WMO, which brings together eight climate data sets from around the world, said six of them - including the European Union's European Centre for Medium-Range Weather Forecasts and the UK's National Meteorological Service - ranked 2025 as the third warmest year, while two ranked it second in the 176-year record.
All eight datasets confirmed that the last three years were also the three warmest on record, the WMO said. The warmest year ever recorded was 2024, Reuters reports.
Minor differences in rankings between the datasets reflect different methodologies and types of measurements - including satellite data and readings from weather stations.
ECMWF said that 2025 also concluded the first three-year period in which the average global temperature was 1,5 degrees Celsius above pre-industrial levels - a threshold that scientists expect, when exceeded in the long term, global warming will trigger severe consequences, some of which will be irreversible.
"1,5 degrees is not the edge of a cliff. However, we know that every tenth of a degree matters, especially when it comes to worsening extreme weather events," said Samantha Burgess, strategic climate manager at ECMWF.
Burgess said she expects 2026 to be among the five warmest years ever recorded.
Choosing how to manage exceeding the temperature threshold
Governments committed to the 2015 Paris Agreement to try to avoid exceeding global warming of 1,5 degrees Celsius, measured as a multi-decade average of temperature compared to the pre-industrial period.
However, due to the failure to reduce greenhouse gas emissions, that target could now be breached before 2030 - even a decade earlier than estimated at the time the Paris Agreement was signed in 2015, the ECMWF said.
"We will definitely cross it," said Karlo Buontempo, director of the EU's Copernicus Climate Change Service.
"The choice we now have is how best to manage the inevitable overshoot and its consequences for societies and natural systems."
Currently, the long-term level of global warming is about 1,4 degrees Celsius above pre-industrial levels, ECMWF said. In the short term, average annual temperatures will exceed 1,5 degrees Celsius for the first time in 2024, Reuters reported.
Extreme weather conditions
Exceeding the long-term threshold of 1,5 degrees Celsius would lead to more frequent and widespread extreme events, including hotter and longer heat waves, as well as more intense storms and floods.
Already in 2025, forest fires in Europe produced the highest total emissions ever recorded, while scientific studies confirmed that certain weather events were further exacerbated by climate change – among them Hurricane Melissa in the Caribbean and monsoon rains in Pakistan, which claimed more than 1.000 lives in floods.
Despite these growing implications, climate science faces political resistance. US President Donald Trump, who has called climate change "the greatest hoax", last week withdrew the US from dozens of United Nations bodies, including the scientific Intergovernmental Panel on Climate Change.
The long-standing consensus among scientists around the world is that climate change is real, largely caused by human activity, and getting worse. Its main cause is greenhouse gas emissions from the burning of fossil fuels such as coal, oil, and gas, which trap heat in the atmosphere.
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