The Earth’s warming rate will reach an all-time high in 2023, with 92% of last year’s astonishing record-breaking heat caused by humans, top scientists have calculated.
The group of 57 scientists from around the world used United Nations-approved methods to examine what was behind last year’s deadly heat explosion. They said that despite a higher rate of warming, they saw no evidence of a significant acceleration in human-caused climate change beyond increased fossil fuel consumption.
Last year’s record temperatures were so unusual that scientists are debating what’s behind the big jump, whether climate change is accelerating or whether other factors are at play.
“If you see the world accelerating or going through a major inflection point, you’ll see that nothing is happening that way,” said Piers Forster, lead author of the study and a climate scientist at the University of Leeds. “Temperatures are rising and kind of getting worse, which is exactly what we predicted.”
He and a co-author said this is largely explained by the buildup of carbon dioxide from increased fossil fuel use.
Last year the warming rate reached 0.26 degrees Celsius (0.47 degrees Fahrenheit) per decade; the previous year it was 0.25 degrees Celsius (0.45 Fahrenheit). Forster said although this year’s rate was the highest ever, it wasn’t a significant difference.
Still, outside scientists said the report highlights a situation that is more worrying than ever.
“Choosing to act on climate has become a political debate, but this report should remind people that this is fundamentally a choice to save human lives,” said Andrea Dutton, a climate scientist at the University of Wisconsin. international working team. “To me, that’s something worth fighting for.”
The team of writers, formed to provide annual scientific updates between major UN scientific assessments every seven to eight years, determined that last year was 1.43 degrees Celsius warmer than the 1850 to 1900 average, with 1.31 degrees Celsius caused by human activities. The other 8% of warming is mostly due to El Niño, a natural and temporary warming of the central Pacific that changes weather around the world, as well as anomalous warming across the Atlantic and other weather randomness.
The report in the journal Earth System Science Data found that the world has warmed by about 1.19 degrees Celsius (2.14 degrees Fahrenheit) since pre-industrial times, over a broader 10-year period that scientists prefer instead of a single year.
The report also stated that as the world continues to use coal, oil and natural gas, the Earth will reach a point within 4.5 years where it can no longer avoid the internationally agreed warming threshold of 1.5 degrees Celsius (2.7 Fahrenheit).
This dovetails with earlier studies that predicted Earth would stabilize, or be stuck, at at least 1.5 degrees by early 2029 if emission trajectories do not change. Forster said it may take years to reach 1.5 degrees, but it will be inevitable if all carbon is used.
Scientists said that it is not the end of the world or humanity if temperatures exceed the 1.5 limit, but the situation will be quite bad. Past UN studies have shown that major changes to Earth’s ecosystem are more likely to lead to a warming of 1.5 to 2 degrees Celsius, including the eventual loss of the planet’s coral reefs, Arctic sea ice, and plant and animal species, as well as worse extreme weather events. shows that it is. kill people.
Last year’s temperature increase was more than just a small jump. September was particularly unusual, said study co-author Sonia Seneviratne, chair of land-climate dynamics at ETH Zurich, a Swiss university.
Seneviratne said the year was within the predicted range, although it was at the upper end of the range.
“If that were to happen, the acceleration would be even worse, probably the worst-case scenario, like reaching a global tipping point,” Seneviratne said. “But what is happening is already extremely bad and already having major impacts. “We are in the middle of a crisis.”
University of Michigan environment dean Jonathan Overpeck and Berkeley Earth climate scientist Zeke Hausfather (neither of whom was part of the study) said they still see acceleration. Hausfather noted that the rate of warming is considerably higher than the 0.18 degrees Celsius (0.32 Fahrenheit) per decade of warming between 1970 and 2010.
Scientists had theorized several explanations for the big jump in September, which Hausfather called “nonsense.” Wednesday’s report did not find enough warming from other potential causes. The report said that reducing sulfur pollution from shipping, which provides some cooling to the atmosphere, has been insufficient due to carbon particles released into the air from wildfires in Canada last year.
The report also noted that an undersea volcano that injects large amounts of heat-trapping water vapor into the atmosphere also spews out cooling particles where both forces largely cancel each other out.
“The future is in our hands,” said Katharine Hayhoe, Texas Tech climate scientist and the Nature Conservancy’s chief scientist. “It is we — humans, not physics — who will determine how fast and how much the Earth will warm.”
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