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Six Spongy Sea Creatures Suggest Warming Might Be Worse Than Thought

全球变暖
气候变化
海绵研究
Since the dawn of the ‎ age, our ‎ has warmed the planet by considerably more than today’s most widely ‎ estimates imply, according to a team of scientists who have ‎ ‎ new information about Earth’s past ‎ from an unusual ‎: ‎-old sponges living in the Caribbean Sea.
Networks of satellites and sensors have ‎ the ‎ temperatures of ‎ decades with great precision. But to assess the ‎ arc of global warming, scientists typically ‎ this data with 19th-‎ thermometer readings that were often ‎ and ‎.
This is where the sponges come in. By ‎ the chemical ‎ of their skeletons, which the ‎ built up steadily over ‎, the ‎ have ‎ a new history of those earliest decades of warming. And it points to a ‎ ‎: Humans have raised global temperatures by a ‎ of about 1.7 ‎ Celsius, or 3.1 Fahrenheit, not 1.2 ‎ Celsius, the most ‎ ‎ ‎.
“It’s a bit of a wake-up call,” said Malcolm T. McCulloch, a geochemist at the University of Western Australia and one of the scientists who ‎ on the new ‎.
Climate ‎ ‎ at the ‎ amount by which ‎ has warmed the planet to ‎ when we might ‎ the ‎ of a hotter Earth — deadlier ‎ ‎, stronger storms, more destructive wildfires — to reach ‎ ‎. If our ‎ ‎ the ‎ more than previously believed, then the clock on ‎ ‎ change might effectively have started earlier than we think.
With the new findings, “we may have brought things ‎ by about a decade,” Dr. McCulloch said. He and his colleagues’ ‎, published Monday in the ‎ Nature Climate Change, ‎ to other ‎ ‎ that ‎ started warming the planet earlier than 19th-‎ temperature ‎ ‎.
Scientists and governments still ‎ those older ‎ as the ‎ for ‎ ‎ warming, largely for ‎ reasons: They aren’t ‎, but they’re a ‎ that everyone can more or less agree on.
That’s why ‎ ‎ who weren’t ‎ in the new study ‎ ‎ about ‎ the Caribbean sponge data to conclude that prevailing estimates of the planet’s warming should be tossed out.
Measurements from any ‎ location can only tell you so much about the ‎ ‎, said Hali Kilbourne, a geological ‎ at the University of Maryland Center for Environmental Science. “I would want to ‎ more ‎ before ‎ a global temperature ‎,” Dr. Kilbourne said.
The heroes of the new study are a ‎-lived type of sponge called ‎. They are small and round, about the size of a grapefruit. They dwell in deep, dimly ‎ undersea ‎ and ‎. And they grow ‎ ‎ in a ‎ that ‎ chemical ‎ of the temperature of the waters that wash ‎ them ‎ the ‎.
The ‎ ‎ samples from six live sclerosponges that a ‎ team from the University of Puerto Rico at Mayagüez collected off the ‎ of Puerto Rico and St. Croix, in the U.S. Virgin Islands, from depths of up to 300 feet.
Six is not a large number of ‎. But these sponges ‎ so far ‎ that scientists need submersibles or ‎ ‎ ‎ to find them. Neither option is cheap.
“They’re just very hard to get to,” Brad E. Rosenheim, a geological ‎ at the University of South ‎, said of sclerosponges. All in all, scientists ‎ have ‎ only ‎ collected something on the ‎ of 50 members of this ‎, said Dr. Rosenheim, who didn’t ‎ on the new study.
The study’s ‎ first compared the most ‎ chemical changes ‎ in the sponges’ skeletons ‎ measurements of global sea-‎ temperatures from the past six decades. The numbers lined up nicely. The ‎ then ‎ ‎ the rest of the sponge data to ‎ a ‎ history of ‎ warming going back to 1700.
Their history ‎ that ‎ temperatures stayed mostly ‎ ‎ 1790. The seas then cooled somewhat because of ‎ volcanic ‎. And then, in the mid-1860s, they began to warm. By the middle of the 20th ‎, the amount of warming that had taken ‎ across both sea and land, when ‎ ‎ the sponge ‎, was about ‎ a ‎ Celsius greater than scientists currently estimate. That gap has persisted to this day, the ‎’ data shows.
The ‎ these ‎ specimens called home is uniquely situated to tell us about ‎ temperatures globally, said Amos Winter, a professor of earth and environmental systems at Indiana State University who ‎ on the study.
Past ‎ has shown that the temperature of the Caribbean’s waters closely ‎ the ‎ ‎ of the ‎ ‎. And, because ‎ live so deep ‎ the ‎, the waters ‎ them don’t ‎ in temperature as much as those at the ‎.
“It’s ‎ one of the best ‎” to study larger ‎ trends, Dr. Winter said. “The changes in Puerto Rico mimic the changes in the ‎.” The new findings raise ‎ ‎ about whether governments will be able to ‎ global warming to 2 ‎ Celsius and, if possible, 1.5 Celsius, as ‎ under the 2015 ‎ Agreement.
But the study’s ‎ for the ‎ ‎ aren’t straightforward, said Joeri Rogelj, a ‎ scientist at Imperial College London who wasn’t ‎ in the ‎.
The targets ‎ ‎ based on scientists’ predictions about how much worse the ‎ of global warming will get compared with ‎ between 1986 and 2005, not ‎ during ‎ times, Dr. Rogelj said. Revised temperature estimates for the 19th ‎ ‎ wouldn’t ‎ change our ‎ of whether these guardrails have been ‎, he said.
There is still ‎ reason to be ‎ about how quickly we are now ‎ the harmful ‎ of warming, said Gabi Hegerl, a ‎ scientist at the University of ‎ who also wasn’t ‎ in the study. “Some of the ‎ of ‎ change that we’re seeing today are quite ‎,” Dr. Hegerl said.
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Six Spongy Sea Creatures Suggest Warming Might Be Worse Than Thought | Leximory