by The rate of global warming was at a record high in 2023 with 92% of last year’s surprising heat being man-made, top scientists calculate.
The group of 57 scientists from around the world used methods approved by the United Nations to examine what is behind last year’s deadly burst of heat. Even with a faster rate of warming, they said they see no evidence of a significant acceleration of human-caused climate change beyond increased fossil fuel burning.
Last year’s record high temperatures were so unusual that scientists are debating what is behind the big jump and whether climate change is accelerating or other factors are at play.
“If you look at the world accelerating or going through a major tipping point, study author Piers Forster, a climate scientist from the University of Leeds, is not doing that just as we predicted.”
It’s largely explained by the increase in carbon dioxide from rising fossil fuel use, he and a co-author said.
Last year the rate of warming hit 0.26 degrees Celsius (0.47 degrees Fahrenheit) per decade – up from 0.25 degrees Celsius (0.45 degrees Fahrenheit) the year before. That’s not a significant difference, although it makes this year’s rate the highest ever, Forster said.
Still, outside scientists said this report shows a more alarming situation.
“Choosing to act on climate is now a political talking point but this report should remind people that saving a human life is a fundamental choice,” said University of Wisconsin climate scientist Andrea Dutton. which was not part of it. the international studies team. “To me, that’s worth fighting for.”
The team of authors – set up to provide annual scientific updates between the UN’s major scientific assessments every seven to eight years – found that last year it was 1.43 degrees Celsius warmer than average between 1850 and 1900 with 1.31 degrees of that coming from human activity. The other 8% of warming is mostly due to El Nino, the natural and temporary warming of the central Pacific that changes weather around the world and also freak warming along the Atlantic and just other weather randomness.
On a larger 10-year time frame, which scientists prefer to individual years, the world has warmed by about 1.19 degrees Celsius (2.14 degrees Fahrenheit) since pre-industrial times, the report in the journal Earth System Science Data found.
The report added that as the world continues to use coal, oil and natural gas, the Earth is likely to reach the point in 4.5 years where it can no longer avoid the internationally accepted warming threshold: 1.5 degrees Celsius (2.7 degrees Fahrenheit).
That fits with earlier studies that projected the Earth to be committed or stuck to at least 1.5 degrees by early 2029 if emissions trajectories don’t change. The actual 1.5 degree hit could be years later, but it would be inevitable if all that carbon is used up, Forster said.
It won’t be the end of the world or humanity if the temperature blows over the 1.5 limit, but it will be pretty bad, the scientists said. Past United Nations studies have shown that between 1.5 and 2 degrees Celsius of warming is likely to see massive changes to Earth’s ecosystems, including the planet’s coral reefs, Arctic sea ice, plant and animal species – such as together with worse extreme weather events. kill people.
Last year’s temperature rise was more than a small jump. It was particularly unusual in September, said study co-author Sonia Seneviratne, head of terrestrial climate dynamics at ETH Zurich, a Swiss university.
The year was within the range of what was predicted, although it was at the upper end of the range, Seneviratne said.
“It would be an acceleration if it happened even worse, like hitting a global tipping point, probably the worst case scenario,” Seneviratne said. “But what’s happening is already very bad and it’s already having big 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 were part of the study, said they still see an acceleration. Hausfather pointed out that the rate of warming is much higher than the 0.18 degrees Celsius (0.32 degrees Fahrenheit) per decade of warming it was between 1970 and 2010.
Scientists have theorized a few explanations for the huge jump in September, which Hausfather called “gobsmacking”. Wednesday’s report found insufficient heating from other possible causes. The report said a reduction in sulfur pollution from shipping – which was providing some cooling to the atmosphere – was overwhelmed last year by carbon particles sent into the air by Canadian wildfires.
The report also said that an undersea volcano injecting massive amounts of heat-trapped water vapor into the atmosphere was also spewing cooling particles and the two forces pretty much canceled each other out.
Texas Tech climate scientist and chief scientist at The Nature Conservancy Katharine Hayhoe said that “the future is in our hands. It’s up to us — not physics, but people — to decide how fast the world goes and how much.”
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