2024 was the hottest year on record, NASA and NOAA confirm

Amid a week of horrifying wildfires in Los Angeles, government agencies in the U.S. and around the world confirmed Friday that 2024 was the planet’s hottest year since recordkeeping began in 1880.

It’s the 11th consecutive year in which a new heat record has been set, NASA Administrator Bill Nelson said.

“Between record-breaking temperatures and wildfires currently threatening our centers and workforce in California, it has never been more important to understand our changing planet,” Nelson said.

Firefighters on Friday were battling to protect NASA’s Jet Propulsion Laboratory in La Cañada Flintridge from the Eaton fire, which has burned 13,690 acres and roughly 5,000 buildings thus far.

Research has shown that global warming is contributing significantly to larger and more intense wildfires in the western U.S. in recent years, and to longer fire seasons.

The devastating fires in Southern California erupted after an abrupt shift from wet weather to extremely dry weather, a bout of climate “whiplash” that scientists say increased wildfire risks. Research has shown that these rapid wet-to-dry and dry-to-wet swings, which can worsen wildfires, flooding and other hazards, are growing more frequent and intense because of rising global temperatures.

Extreme weather events in 2024 included Hurricane Helene in the southeastern U.S., devastating floods in Valencia, Spain, and a deadly heat wave in Mexico so intense that monkeys dropped dead from the trees, noted Russell Vose, chief of the monitoring and assessment branch of NOAA’s National Centers for Environmental Information.

“We aren’t saying any of these things were caused by changes in Earth’s climate,” Vose said. But since warmer air holds more moisture, the higher temperatures “could have exacerbated some events this year.”

Last year’s data also notes a step toward a major climate threshold. Keeping the average global surface temperature from rising 1.5 degrees Celsius above pre-industrial levels has long been seen as necessary to avoid many of the most harrowing climate impacts.

NOAA pegged 2024’s global average surface temperature at 1.46 degrees C above its preindustrial baseline, and NASA’s measurements put the increase at 1.47 degrees C. In 2023, NASA said the temperature was 1.36 degrees C higher than the baseline.

Considering the margin of error in their measurements, “that puts the NOAA and NASA models comfortably within the possibility that the real number is 1.5 degrees,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.

Calculations from other organizations passed the 1.5-degree mark more clearly.

Berkeley Earth and the European Union’s Copernicus Climate Change Service both said the planet warmed to slightly more than 1.6 degrees C above pre-industrial times in 2024. The United Nations’ World Meteorological Organization said the increase was 1.55 degrees C and the U.K. Met Office, the country’s weather service, measured an increase of 1.53 degrees C.

Although 2024 probably marks the first calendar year in which the average temperature exceeded the 1.5-degree threshold, it doesn’t mean Earth has passed the crucial target set in the Paris Agreement, Vose said.

That describes “a sustained, multi-decade increase of 1.5 degrees,” something that’s not expected to occur until the 2030s or 2040s, the scientists noted.

“For a long time, the global mean temperature changes were a bit of an esoteric thing — nobody lives in the global mean,” Schmidt said. “But the signal is now so large that you’re not only seeing it at the global scale … you’re seeing it at the local level.”

“This is now quite personal,” he said.

The oceans, which store 90% of the planet’s excess heat, also recorded their highest average temperature since records began in 1955.

The Arctic has seen the most warming, which is concerning because the region is home to vast quantities of ice that stands to melt and raise sea levels, Schmidt said.

Temperatures there are rising 3 to 3.5 times faster than the overall global average, he added.

The only place where average surface temperatures have cooled is the area immediately around Antarctica, and that’s probably due to meltwater from shrinking ice sheets, Schmidt said.

A year ago, NOAA predicted there was only a 1 in 3 chance that 2024 would break the record set in 2023, Vose said. Then every month from January to July set a new high, and August was a tie. As a result, Friday’s declaration came as little surprise.

The longer-term trends are no better.

“We anticipate future global warming as long as we are emitting greenhouse gases,” Schmidt said. “That’s something that brings us no joy to tell people, but unfortunately that’s the case.”

Times staff writer Ian James contributed to this report.