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.
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.
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.