Islamabad/Geneva: Even a cooling La Niña at the start and end of the year could not slow the planet’s heating, with the World Meteorological Organization confirming that 2025 ranked among the three warmest years ever recorded, extending an unprecedented run in which the past 11 years have all been the warmest on record.
In its consolidated global assessment, the WMO said the average surface temperature in 2025 was about 1.44 degrees Celsius above the 1850 to 1900 pre industrial average, a level that underscores how deeply heat trapping greenhouse gases have altered the climate system. Across eight leading international datasets, two ranked 2025 as the second warmest year in a 176 year record, while six placed it third.
The organisation noted that the three year period from 2023 to 2025 now stands as the warmest three year stretch ever observed, with an average warming of 1.48 degrees Celsius above pre industrial levels. The 11 year period from 2015 to 2025 has also emerged as the hottest on record across all datasets, highlighting the persistence of the warming trend despite natural climate variability.
“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,” said WMO Secretary General Celeste Saulo.
She said high land and ocean temperatures helped fuel extreme weather, including heatwaves, heavy rainfall and intense tropical cyclones, reinforcing the need for strong early warning systems.
The WMO’s analysis brings together data from major global climate centres, including NASA, NOAA, the UK Met Office, the European Copernicus Climate Change Service, Japan’s meteorological agency and Berkeley Earth, alongside two additional datasets incorporated for the first time from China and a UK US collaboration. By consolidating these sources, the WMO aims to provide a single authoritative temperature assessment to guide governments and decision makers.
Scientists say the signal from the oceans is particularly alarming. A separate peer reviewed study cited by the WMO found that ocean heat content in 2025 was among the highest ever recorded, reflecting the long term build up of excess heat in the climate system. About 90 percent of the additional heat from global warming is absorbed by the oceans, making ocean warming a critical indicator of climate change.
According to the study, the upper 2000 metres of the global ocean gained an estimated 23 zettajoules of heat between 2024 and 2025, roughly equivalent to 200 times the world’s total electricity generation in 2024. Large areas of the global ocean, including the Indian Ocean basin, Mediterranean and Southern Ocean, ranked among their warmest conditions on record.
For countries like Pakistan, which already face rising temperatures, erratic monsoons, floods and heatwaves, the findings carry serious implications even if they were not the focus of the WMO assessment. Climate experts warn that continued global warming increases the likelihood of extreme heat events, glacial melt in the north and more intense rainfall episodes, all of which have direct consequences for water security, agriculture and public health.
The WMO said it will release a more detailed State of the Global Climate 2025 report in March, covering greenhouse gas levels, sea level rise, glacier retreat and high impact weather events. With global temperatures continuing to push into record territory, the organisation stressed that robust data sharing and climate monitoring are now more critical than ever to help countries prepare for what lies ahead.