The numbers are in, and scientists can now confirm which month after month of extreme heat worldwide began to signal a long time ago. Last year was the warmest on Earth by a century and a half.
Global temperatures began breaking records in the middle of the year and have not stopped. First, June was the planet’s hottest June on record. Back then, July was the hottest July. And so on, until December.
On average, global temperatures last year were 1.48 degrees Celsius, or 2.66 Fahrenheit, warmer than in the second half of the 19th century, the European Union’s Copernicus Climate Change Service said this week. This is warmer by quite a margin than 2016, the previous warmest year.
On Friday, NASA scientists found that the global average temperature in 2023 was about 1.37 degrees Celsius above pre-industrial levels, while last year it was 1.34 degrees Celsius above the pre-industrial average, according to the National Oceanic and Atmospheric Administration. term.
Each organization uses different methods to calculate their numbers. But everyone agrees that 2023 was the warmest year on record by a wide margin.
“This is a big jump,” Russell Vose, head of climate monitoring and assessment at NOAA’s National Centers for Environmental Information, said during an event announcing the agency’s results on Friday.
It is no surprise to climate scientists that unabated emissions of greenhouse gases have caused global warming to reach new highs. What researchers are still trying to figure out is whether 2023 heralds many more years in which heat records are not just broken, but broken. In other words, they ask whether the numbers are a sign that global warming is accelerating.
When scientists combine their satellite readings with geological evidence of the climate’s most distant past, 2023 also appears to be among the warmest years in at least 100,000, Carlo Buontempo, director of the European Union’s climate monitoring, said on Tuesday. “There were simply no cities, books, agriculture or domesticated animals on this planet the last time the temperature was this high,” he said.
Every 10 degrees of global warming represents additional thermodynamic fuel that intensifies heat waves and storms, adds to rising seas, and accelerates the melting of glaciers and ice sheets.
These results appeared last year. The hot weather baked Iran and China, Greece and Spain, Texas and the American South. Canada had by far the most destructive fire season on record, with more than 45 million acres burned. Less sea ice formed around the Antarctic coast, both in summer and winter, than had ever been measured.
“We need to be prepared for the effects of climate change happening here and now, such as extreme events becoming more frequent and more severe,” Sarah Kapnick, NOAA’s chief scientist, said at Friday’s event. Dr. Kapnick said she hopes communities, businesses and individuals will use the data released by her agency and others to prepare and build resilience for the future.
Under the 2015 Paris Agreement, nations agreed to limit long-term global warming to 2 degrees Celsius and, if possible, to 1.5 degrees. At current rates of greenhouse gas emissions, it will be only a few years before the 1.5 degree target is a lost cause, researchers say.
Carbon dioxide and other greenhouse gases are the main driver of global warming. But last year several other natural and man-made factors also helped increase temperatures.
The 2022 eruption of an undersea volcano off the Pacific island nation of Tonga spewed massive amounts of water vapor into the atmosphere, helping to trap more heat near the Earth’s surface. Recent limits on sulfur pollution from ships have reduced levels of aerosols, or tiny suspended particles that reflect solar radiation and help cool the planet.
Another factor was El Niño, the recurring change in weather patterns in the tropical Pacific that began last year and is often associated with record-setting heat worldwide. And that contains a warning of potentially worse to come this year.
The reason: In recent decades, very warm years have typically been the ones that started in an El Niño state. But last year, El Niño started before the middle of the year — suggesting that El Niño wasn’t the main driver of the abnormal heat at that point, said Emily J. Becker, a climatologist at the University of Miami.
It’s also a strong sign that this year may be hotter than last year. “It’s very, very likely to be the top three, if not the record,” Dr Becker said, referring to 2024.
Scientists warn that a single year, even one as extraordinary as 2023, can tell us so much about how long-term global warming might change. But other signs show the world is warming faster than before.
About 90 percent of the energy trapped by greenhouse gases accumulates in the oceans, and scientists have found that the uptake of heat by the oceans has accelerated significantly since the 1990s. “If you look at this curve, it’s clearly not linear,” said Sarah Perkey, an oceanographer at the Scripps Institution of Oceanography at the University of California, San Diego.
A group of researchers in France recently found that the Earth’s overall warming – in the oceans, land, air and ice – had accelerated for even more, since 1960. This broadly matches the increases in carbon emissions and decreases in aerosols in recent decades.
But scientists should continue to study the data to understand whether other factors might be at work, said one of the researchers, Karina von Schuckmann, an oceanographer at Mercator Ocean International in Toulouse, France. “Something unusual is happening that we don’t understand,” said Dr. von Schuckmann.
Delger Erdenesanaa contributed to the report.