In 2025, weather conditions set a record somewhere every day. These were often relatively harmless outliers. For example, a mild autumn in De Bilt, the Netherlands, resulted in the warmest November 5 ever recorded: a pleasant 18.0 degrees Celsius. Sometimes the consequences were downright devastating, such as in the Thai city of Hat Yai, where 335 millimeters of rainfall fell in one day that same month, resulting in dozens of deaths.
These types of weather extremes are the result of climate change, but are not the best evidence for this. Scientists prefer to look at the averages, which they calculate and publish every year in January. The same goes for it annual review published on Wednesday from Copernicus, the European Union’s climate agency.
It shows that 2025 will be the third warmest year on record, with a global average of 14.97 degrees. That is 1.47 degrees higher than before the industrial revolution, when humans started the greenhouse effect by burning fossil fuels.
Only 2024 and 2023 were even warmer, with 1.48 and 1.60 degrees of warming respectively. As a result, the three-year average is higher than one and a half degrees for the first time and the ambitious goal of the Paris Agreement, to keep the long-term average below that, will probably be accomplished this decade. When the agreement was concluded in 2016, it was expected that this would only happen ten years later.
Polar regions are warming faster
The high average temperature of the past year is largely due to the rapid warming of the polar regions. Previous research already showed that the Arctic almost four times is warming faster than the rest of the Earth. This is at least partly due to a self-reinforcing effect: the white ice melts and can therefore reflect less sunlight, causing the dark seawater to absorb heat and further increase warming.
Antarctica was warmer than ever last year, with the Arctic achieving the second highest annual average, according to Copernicus figures. This causes the ice to melt faster than ever before. The combined ice area of both poles reached the lowest level since satellite recording began in the 1970s.
The extreme heat of the past three years was not only the result of greenhouse gases in the atmosphere, Copernicus writes in the accompanying press release. It also had to do with “exceptionally high” sea surface temperatures, which were related to “an El Niño phenomenon and other factors affecting the ocean.” These types of periodic changes in the sea current are not the result of climate change, the report emphasizes, but they are amplified by it.
Oceans absorb heat
The oceans absorbed more solar energy than ever last year, according to a study in the scientific journal on Friday Advances in Atmospheric Sciences. That is the ninth annual record in a row. was 23 zettajoules, about the same as two hundred times global electricity use in 2023. This will cause water to warm, ice caps to melt and sea levels to continue to rise.
Last year also “entered the top 10 warmest years for the Netherlands,” it wrote Royal Netherlands Meteorological Institute (KNMI) on its website just before New Year’s Eve. The KNMI immediately added a dark red line to the graph with the ‘climate barcode’ that shows the warming of the Netherlands since 1901. Apart from 2022, last year was also the sunniest year ever in the Netherlands.
Whether the number of hours of sunshine will continue to increase worldwide due to climate change is not yet a foregone conclusion for science. The future cloud cover is therefore one of the most important uncertainties in models that try to predict global warming.
At 138 watts per square meter, the solar energy that reached the Netherlands was in any case higher than since measurements began in the 1960s. That is good news for the owners of solar panels that generate record amounts of energy, even if it is not enough to reverse climate change for the time being.
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