Earth passed a critical climate change threshold in 2024, scientists announce
Last year was not only the hottest since record-keeping began in 1850 but was also the first to pass a threshold meant to limit the worst effects of climate change, the Copernicus Climate Change Service said Friday.
U.S. scientists also found that 2024 was the globe's hottest on record, and that the heat in the uppermost layer of the ocean was record high, scientists from the National Oceanic and Atmospheric Administration and the National Aeronautic and Space Administration said Friday.
"It's clear that each of the past four to five decades have been warmer than the decade that preceded it," said Russell Vose, chief of the monitoring and assessment branch for NOAA's National Centers for Environmental Information. "There's been a long-term increase since at least the 1960s."
The federal agencies also reported it the warmest year on record in the U.S.. The average annual temperature – 55.5 degrees – was 3.3 degrees above average.
The announcements by several major climate observation organizations, including Copernicus, NOAA, NASA and Berkeley Earth, were made on the same day by prior agreement.
Regardless of how the data is collected or compiled by the various tracking organizations, the trends they are mapping are the same, said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies.
"All of the internationally produced global temperature datasets show that 2024 was the hottest year since records began in 1850,” Copernicus director Carlo Buontempo said in a statement.
The setting of a new record warm temperature – for the second year in a row – has prompted further pleas from many organizations for more effective and expedient action to try to reign in the warming temperatures, the greenhouse gas emissions that exacerbate the warming and the impacts from more intense severe weather events.
That includes events like the drought in California that helped to fuel the firestorm in Los Angeles this week and the extreme rainfall that devastated Western North Carolina as Hurricane Helene and its remnants moved through.
"The future is in our hands - swift and decisive action can still alter the trajectory of our future climate,” Buontempo stated. “Humanity is in charge of its own destiny but how we respond to the climate challenge should be based on evidence.”
The milestones listed by Copernicus include:
◾ The global average was 1.3 degrees above the 1991-2020 global average and .21 degrees above 2023, the previous warmest year on record.
◾ The temperature was 2.9 degrees above the estimated temperature between 1850-1900, often referred to as the preindustrial era.
◾ Each of the past 10 years has been one of the warmest 10 on record.
◾ A new record-high daily global average temperature was reached on July 22, at 30.8 degrees.
◾ Every month since July 2023, except for July 2024, was above the 2.7 degrees Fahrenheit (1.5 C) threshold.
◾ The only continental regions that did not see their warmest year on record were Antarctica and Australasia.
Why 2.7 degrees is such a big deal
The record high for 2024 marks a threshold scientists had hoped for years to avoid.
In 2016, the United States and 195 other parties signed the Paris Agreement, a treaty aimed at keeping global warming at bay. They pledged to try as hard as possible to keep the global average temperature increase below 2.7 degrees.
It seems like a small number. But that 2.7 degrees can be the difference between a raging fever and a healthy toddler. Between a hockey rink and a swimming pool. Between food going bad or staying safe.
Now consider that Earth this year was 2.9 degrees hotter on average than it was in the late 1800s. It's little wonder that this has already led to measurable shifts in the climate.
The average of 2.9 degrees hotter may seem insignificant. After all, 65 degrees to 67.9 degrees isn't even worth grabbing a sweater, so why does it worry climate scientists?
Because they're thinking about global temperature averages, and when the global average goes up, the extremes go way up.
We’re already seeing it across America. Storms are more extreme, drenching areas with more water that's causing an increasing number of devastating flash floods. Droughts are more devastating, catastrophic wildfires more common and hurricanes wetter.
Graph shows annual temperature differences above the long-term average
2024 climate data from the US
NOAA also announced that last year was among the third wettest on record in the U.S., dating back to 1895.
The number of tornadoes was the second highest on record behind 2004.
Hurricane Helene’s extensive damage topped a list of 27 separate billion-dollar weather and climate disasters, the second-highest annual number on record.
Berkeley Earth
The record warmth surpassed the previous record set in 2023 by a clear margin, according to a report released Friday by Berkeley Earth, a California-based nonprofit research organization.
Berkeley Earth’s report estimates that 104 countries had their locally warmest year on record, including Brazil, Canada, China, Mexico, Singapore, and South Korea. It estimates about 40% of the Earth’s population – 3.3 billion – live in places that experienced their warmest-ever annual average temperatures.
"The abrupt new records set in 2023 and 2024 join other evidence that recent global warming appears to be moving faster than expected,” said Robert Rohde, Berkeley Earth’s lead scientist. It was the second year in a row to deviate significantly from the long-term warming trend seen over the past 50 years, but it remains uncertain whether the short-term acceleration will become a longer-term trend.
It’s likely the long-term average will pass the 2.7 degrees (1.5 C) milestone in the next five to 10 years, Rohde said. The Berkeley report added more aggressive efforts to reduce greenhouse gas emissions will be necessary to avoid even higher levels of warming and to mitigate more significant impacts from extreme weather events.
Looking ahead to 2025, Berkeley Earth estimates 2025 will likely be the third warmest year on record, due to an expected cooling pattern in the Equatorial Pacific.
Other scientists react
The reports renewed a chorus of concern among scientists, who expressed frustration at the news of another record-warm year.
"This is a scorching red flag that the climate crisis is no longer a distant threat," said Kathryn Matthews, chief scientist for Oceana, an ocean conservation organization. "It's here and it's impacting us all.
"The oceans, which absorb most of this heat, are bearing the brunt of this crisis, putting marine life and coastal economies at serious risk," she said.
Researchers are exhausted after sounding the alarm year after year, Astrid Caldas, a senior climate scientist at the Union of Concerned Scientists said in a statement. "I’m no longer just concerned about the climate crisis and its impacts on vulnerable communities but incensed at world leaders for their grossly inadequate climate action to date."
The last 11 years have been the 11 hottest on record, she added. "Will it take another 11 years for policymakers to heed the irrefutable science and address the devastation being experienced in the United States and around the world largely due to fossil-fuel-driven global warming?"
Sea ice
After reaching record-low values for the time of year in eight months of 2023, sea ice in Antarctica reached record or near-record low values again during much of 2024, ranking the second lowest on record behind 2023 from June to October and ranked lowest in November, Copernicus reported. The sea ice extent in February, when the ice reaches its annual minimum, was the third lowest in the satellite record.
In the Arctic, the sea ice extent was close to its 30-year average from 1991-2020 until July, when it began to fall below average. Its annual minimum low extent in September was the fifth lowest in the satellite record.
Emissions
Atmospheric concentrations of carbon dioxide and methane increased again, reaching record annual levels in 2024, at 422 parts per million, according to Copernicus. Carbon dioxide concentrations in Earth’s atmosphere were 2.9 parts per million higher than in 2023. While carbon dioxide is natural in the atmosphere, scientists say massive increases in emissions have been responsible for the long-term warming trend in temperatures.