Earth’s oceans absorbed 23 ZETTAJOULES of heat in 2025,
Scientists have revealed the incredible amount of heat Earth’s oceans absorbed in 2025.
According to experts from the Chinese Academy of Sciences, a whopping 23 zettajoules of heat were gained last year.
That’s 23,000,000,000,000,000,000,000 Joules of energy – around about enough to boil 69 quadrillion kettles.
Unsurprisingly, this is the highest level ever observed.
‘The year 2025 started and ended with a cooling La Niña,’ said Celeste Saulo, Secretary–General of the World Health Organisation.
‘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.’
The news comes shortly after it was confirmed that 2025 was the third hottest year on record, following 2023 and 2024.
From floods to droughts, many of the consequences of climate change happen on land.
However, the ocean actually absorbs more than 90 per cent of excess heat trapped by greenhouse gases – making it the main heat resevoir of the climate system.
‘Because ocean heat content (OHC) reflects the accumulation of heat stored in the ocean, it provides one of the best indicators of long–term climate change,’ the team explained.
As part of their assessment, the researchers combined data from three continents – Asia, Europe, and America.
While 23 zettajoules were absorbed overwall, the ocean warming was not uniform, with some areas warming faster than others.
In 2025, the warmest areas included the tropical and South Atlantic and North Pacific Oceans, as well as the Southern Ocean.
‘Ocean heat content reached a record high in 2025 as it has in each of the past nine years,’ the researchers added.
The additional heat is not only devastating marine life – but is also causing sea levels to rise, according to the experts.
‘Rising ocean heat drives global sea–level rise via thermal expansion, strengthens and prolongs heatwaves, and intensifies extreme weather by increasing heat and moisture in the atmosphere,’ they explained.
‘As long as the Earth’s heat continues to increase, ocean heat content will continue to rise and records will continue to fall.’
Based on the findings, the team are calling for urgent action to curb global emissions.
‘The biggest climate uncertainty is what humans decide to do,’ they concluded.
‘Together, we can reduce emissions, better prepare for upcoming changes, and help safeguard a future climate where humans can thrive.’
