2024 has been the warmest year on record

In 2024, the average temperature of the Earth’s surface was the warmest of any recorded since systematic measurements began.

This has been determined in an analysis led by NASA scientists.

“Once again, the temperature record has been broken: 2024 was the warmest year since records began to be kept in 1880,” says NASA Administrator Bill Nelson. Global warming is advancing at full speed.

Global temperatures in 2024 were 1.28 degrees Celsius above the average for the reference period used by NASA (1951 to 1980), surpassing the record set in 2023. The new all-time high comes after 15 consecutive months (since June 2023 to August 2024) of monthly temperature records, a streak of unprecedented extreme heat.

NASA scientists also estimate that in 2024 the Earth will be around 1.47 degrees Celsius warmer than the average for the mid-19th century (1850-1900). For more than half of 2024, average temperatures were 1.5 degrees Celsius above the reference level, and the annual average, with mathematical uncertainties, could have exceeded the level for the first time.

“The Paris Agreement on climate change sets out efforts to stay below the 1.5 degree level in the long term. To put that into perspective, temperatures during warm periods on Earth three million years ago (when sea level was tens of meters higher than today) were only about 3 degrees Celsius warmer than levels shortly before begin the Industrial Revolution,” explains Gavin Schmidt, director of NASA’s Goddard Institute for Space Research (GISS) in New York. “We are halfway to reaching Pliocene heat levels in just 150 years.”

Scientists have concluded that the warming trend of recent decades is being driven by carbon dioxide, methane and other heat-trapping greenhouse gases. According to a recent international analysis, in 2022 and 2023 the Earth saw a record increase in carbon dioxide emissions from fossil fuels. The concentration of carbon dioxide in the atmosphere has increased from pre-industrial levels in the 18th century, which were about 278 parts per million, to about 420 parts per million today.

NASA and other US federal agencies regularly collect data on greenhouse gas concentrations and emissions. These data are available from the US Greenhouse Gas Center, a multi-institution initiative that consolidates information from observations and models, to provide decision makers with a single point of access to data and analysis.

Temperatures each year can be influenced by natural climate fluctuations such as El Niño and La Niña, which alternately warm and cool the tropical Pacific Ocean. The strong El Niño event that began in the fall of 2023 contributed to global temperatures surpassing previous records.

The heat wave that began in 2023 continued to exceed expectations in 2024, according to Schmidt, even though the El Niño subsided. Researchers are working to identify factors contributing to this phenomenon, including possible climate effects from the January 2022 Tonga volcanic eruption and pollution reductions, which may change cloud cover and the way that solar energy is reflected back into space.

“Not every year is going to break records, but the long-term trend is clear,” Schmidt said. “We are already seeing the impact in extreme rainfall, heat waves and increased risk of flooding, which will continue to worsen as emissions continue.”

This map of Earth in 2024 shows global surface temperature anomalies, that is, how much hotter or colder each region of the planet was compared to the average from 1951 to 1980. Normal temperatures are shown in white, those above normal in red and orange, and those below normal in blue. (Image: NASA Scientific Visualization Studio)

NASA compiles its temperature record from surface air temperature data collected by tens of thousands of weather stations, as well as sea surface temperature data acquired by instruments on ships and buoys. To analyze these data, methods are used that take into account the varied spacing of temperature stations globally and the effects of urban warming that could bias the calculations.

Independent analyzes by NOAA, Berkeley Earth, the Hadley Center (part of the UK Met Office) and the Copernicus Climate Change Service in Europe have also concluded that global surface temperatures for 2024 were the highest since modern records began. These scientists use much of the same temperature data in their analyses, but employ different methodologies and models. They all show the same warming trend. (Source: NASA)