From SCIENCE Magazine, published by the American Association for the Advancement of Science:
It’s a record foretold: 2024 was the hottest year in human history, even hotter than the record-breaking year before it. Global surface temperatures were somewhere between 1.45°C and 1.6°C higher than the average from 1850 to 1900, multiple climate monitoring groups reported today. “We are now living in a very different climate from that which our parents and our grandparents experienced,” said Samantha Burgess, deputy director of Europe’s Copernicus Climate Change Service (C3S).
Another 1.5°C of warming would take the world back to the climate of the Pliocene, a time 3 million years ago when sea levels were many meters higher, said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, in the agency’s announcement. “We are halfway to Pliocene-level warmth in just 150 years.”
What’s more, the spike over the past 2 years was the sharpest in modern history, Burgess said. It caught many climate scientists by surprise, surpassing what would be expected just from increasing greenhouse gases. A host of explanations has emerged, some familiar—an El Niño in the Pacific Ocean—and some worrying and enigmatic, including what appears to be a decadeslong decline in cloud cover. The fear is warming could be accelerating faster than expected, owing to a poorly understood feedback in the climate system.
Taking the temperature of the previous year has become an increasingly grim January tradition. In recent years, NASA and the National Oceanic and Atmospheric Administration in the United States and the United Kingdom’s Met Office have been joined by C3S, Berkeley Earth, and an international group of ocean scientists, with each group emphasizing different methods of stitching together the data from thousands of land-based thermometers, ocean buoys, and satellites. In the deep ocean, which is destined to absorb most of the energy from global warming, nearly every year is a new record. At the surface, not every year is—but each of the past 10 years has been among the hottest 10 years in history.
At first blush, the planet might seem to have passed the ambitious target of limiting warming to 1.5°C set by the Paris agreement in 2015. But because temperatures fluctuate naturally from year to year, climate scientists say, what counts is the long-term average, which currently sits between 1.2°C and 1.4°C. It may take 5 or 10 years for the Paris target to be clearly breached.
In some ways, 2024 was less exceptional than 2023, even if it was warmer, Schmidt said. In 2023, surface temperatures jumped by nearly 0.3°C in a year; this past year, they finished some 0.1°C higher than 2023. The 2023 jump coincided with a strong El Niño that set in during the second half of the year. With El Niño now having given way again to La Niña, its cooling counterpart, “the spike has ended,” says Shiv Priyam Raghuraman, a climate scientist at the University of Illinois Urbana-Champaign.
The pressing question for climate science is to understand what happened in 2023 and whether El Niño is the full explanation . Recent work by Raghuraman has shown that the arrival of El Niño after a prolonged La Niña from 2020 to 2022 could theoretically explain all of the temperature surge. But the surge began earlier than El Niño in 2023, especially in the North Atlantic Ocean, and lasted longer in 2024, which suggests other factors are at play. In fact, NASA estimated that El Niño only added 0.01°C of warming in 2023.
Early on, some researchers thought cleaner, clearer air due to falling pollution from China and a switch to cleaner ship fuels could explain a significant chunk of the rise. But 2023 might fit into a more alarming trend. For 2 decades, NASA instruments in space have tracked a growing imbalance in Earth’s solar energy budget, with more energy entering than leaving the planet. Although greenhouse gases explain most of the imbalance, the data have also shown the planet is growing less reflective, beyond even what is expected from a decrease in light-reflecting air pollution.
A recent study has suggested a decrease in reflective clouds played a role in the 2023 warming, though what drove those changes is unclear. But more concerning is work presented last month at the annual meeting of the American Geophysical Union and reported by Science, showing that reflective cloud cover has dropped for 2 decades. If this decline holds up, and is found to be caused by global warming—which it then amplifies—then the 2023 spike in temperature may not be an anomaly. It may be a harbinger.
ABOUT THE AUTHOR
1 comment:
You can thank conservative Republicans for that. These people really are a shit stain on humanity.
Post a Comment