Major climate change indicators broke records in 2024
DOI: 10.1063/pt.bucm.weyg
Dark storm clouds gather over South Africa, which is among the regions where a new satellite monitoring program began tracking lightning in 2024. The most recent State of the Climate report, published in August, highlights last year’s climate trends and scientific advancements in Earth monitoring. (Image by Ndumiso Mvelase/Pexels.)
Last year saw the highest air and ocean temperatures on record globally, according to a peer-reviewed report published in August in the Bulletin of the American Meteorological Society. The annual State of the Climate report , now in its 35th year, pulls data from instruments and monitoring stations around the world on land, water, and ice and from space.
The report is an authoritative reference for scientists to follow the trajectory of the climate system on an annual basis, says former American Meteorological Society president Anjuli Bamzai. (The American Meteorological Society is a member society of the American Institute of Physics, the publisher of Physics Today.) The report does not include analyses of model simulations or address climate impacts or mitigation.
Annual surface air temperatures over the land and ocean in 2024 were 0.63–0.72 °C above the 1991–2020 average, according to the report, the highest since recordkeeping began in the mid 1800s. Although a strong El Niño at the beginning of 2024 helped enhance warming, the last 10 years have been the warmest 10 years on record. Sea surface temperatures were nearly half a degree Celsius higher in 2024 than the 1991–2020 average. The ocean has absorbed approximately 90% of Earth’s excess heat from 1971 to 2020.
Last year featured record-breaking humidity as well. On average, a given location experienced about 36 more extremely humid days (days with wet-bulb temperatures 90% above the local normal) than it did annually from 1991–2020. The previous high was 26 days above average in 2023. The higher the wet-bulb temperature, the harder it is for sweat to cool the human body, which can lead to potentially life-threatening conditions.
Glaciers lost more mass than any year since recordkeeping began in 1970, the report says. It was the 37th consecutive year that global glaciers lost more mass than they gained. Venezuela registered the loss of all its glaciers, making it the first country in the Andes to do so.
Global averages for sea level height, annual maximum daily rainfall over land, and concentrations of atmospheric carbon dioxide, methane, and nitrous oxide also reached the highest levels ever recorded.
Other documented measures fell short of records in 2024. For example, the mass loss of the Greenland ice sheet was lower than the 2002–23 annual average. The report says that the region was influenced by the Arctic oscillation index’s positive phase, which locks colder air over the Arctic and blocks warmer air coming from the south. The number of named global tropical cyclones last year, 82, was below the 1991–2020 annual average of 87.
The report also spotlights scientific advancements. The lightning imaging data from Europe’s first Meteosat Third Generation imaging satellite over Europe, Africa, and South America went live last year; lightning strikes can serve as a proxy for tracking extreme weather. And the use of land surface measurements from Europe’s Sentinel satellites shows promise for documenting temperature hot spots in areas with few weather stations.
Nearly 600 scientists from universities, forecast centers, and government labs across 58 countries contributed to the report. Several authors and editors who had participated in the report for decades had “retired prematurely and unexpectedly this year,” according to the report’s acknowledgments. Widespread layoffs have hit US science agencies throughout 2025.
This article was originally published online on 11 September 2025.
