Scientists confirm 2024 as warmest year on record

The World Meteorological Organization (WMO) has confirmed that 2024 is the warmest year on record, based on six international datasets. The past ten years have all been in the Top Ten, in an extraordinary streak of record-breaking temperatures.

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 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.

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

“Individual years pushing past the 1.5-degree limit does 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 data sources to support international climate monitoring and to provide authoritative information for the UN Climate Change negotiating process. The datasets are from the European Centre 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 Climate Research Unit at the University of East Anglia (HadCRUST), 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 emphasise that a year of more than 1.5°C for a year does not mean that we have failed to meet the Paris Agreement long-term temperature goals, which are measured over decades rather than an individual year. However, it is essential to recognise 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. However, not all show a 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 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 at 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 per cent 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 Insitute of Atmospheric Physics dataset.

Guterres called on governments to deliver new national climate action plans this year to limit long-term global temperature rise to 1.5°C, and support the most vulnerable deal with devastating climate impacts.