WMO confirms 2024 as warmest year on record

The global average surface temperature was 1.55 °C (with a margin of uncertainty of ± 0.13 °C) above the 1850-1900 average, according to WMO’s consolidated analysis of the six datasets. This means that we have likely just experienced the first calendar year with a global mean temperature of more than 1.5°C above the 1850-1900 average.

“Today’s assessment from the World Meteorological Organization (WMO) proves yet again – global heating is a cold, hard fact,” said UN Secretary-General Antóno Guterres.

“Individual years pushing past the 1.5 degree limit do not mean the long-term goal is shot. It means we need to fight even harder to get on track. Blazing temperatures in 2024 require trail-blazing climate action in 2025,” he said. “There's still time to avoid the worst of climate catastrophe. But leaders must act – now,” he said.

The WMO provides a temperature assessment based on multiple sources of data to support international climate monitoring and to provide authoritative information for the UN Climate Change negotiating process. The datasets are from the European Center for Medium Range Weather Forecasts (ECMWF), Japan Meteorological Agency, NASA, the US National Oceanic and Atmospheric Administration (NOAA), the UK’s Met Office in collaboration with the Climatic Research Unit at the University of East Anglia (HadCRUT), and Berkeley Earth.

“Climate history is playing out before our eyes. We’ve had not just one or two record-breaking years, but a full ten-year series. This has been accompanied by devastating and extreme weather, rising sea levels and melting ice, all powered by record-breaking greenhouse gas levels due to human activities,” said WMO Secretary-General Celeste Saulo.  

“It is important to emphasize that a single year of more than 1.5°C for a year does NOT mean that we have failed to meet Paris Agreement long-term temperature goals, which are measured over decades rather than an individual year. However, it is essential to recognize that every fraction of a degree of warming matters. Whether it is at a level below or above 1.5°C of warming, every additional increment of global warming increases the impacts on our lives, economies and our planet,” said Celeste Saulo.

There is a margin of uncertainty in all temperature assessments. All six datasets place 2024 as the warmest year on record and all highlight the recent rate of warming. But not all show the temperature anomaly above 1.5 °C due to differing methodologies.

The timing of the release of the six temperature datasets was coordinated across the institutions in order to underline the exceptional conditions experienced during 2024.  

A separate study published in Advances in Atmospheric Sciences found that ocean warming in 2024 played a key role in the record high temperatures. The ocean is the warmest it has ever been as recorded by humans, not only at the surface but also for the upper 2000 meters, according to the study led by Prof. Lijing Cheng with the Institute of Atmospheric Physics at the Chinese Academy of Sciences. It involved a team of 54 scientists from seven countries and 31 institutes.  

About 90% of the excess heat from global warming is stored in the ocean, making ocean heat content a critical indicator of climate change. From 2023 to 2024, the global upper 2000 m ocean heat content increase is 16 zettajoules (1021 Joules), about 140 times the world’s total electricity generation in 2023, according to the study, which is based on the Institute of Atmospheric Physics dataset.

WMO will provide full details of key climate change indicators, including greenhouse gases, surface temperatures, ocean heat, sea level rise, glacier retreat and sea ice extent, in its State of the Global Climate 2024 report to be issued in March 2025. This will also give details of high-impact events.