Growing geological evidence suggests that the Arctic was once a lot warmer than it is today, which is a major problem as we continue to relentlessly pump greenhouse gases into the atmosphere. The latest development is one study Published Wednesday in Science Advances, which uses geological deposits in caves to infer that the region was at least 6.3 degrees Fahrenheit (3.5 degrees Celsius) warmer than it is today, just over 500,000 years ago.
To try to get a sense of what the Arctic’s past looked like, researchers analyzed a 12 cm thick (12 cm thick) calcite mineral deposit they found in a cave in northeast Greenland. Although things are heating up quickly in the Arctic, it is still mostly cold and covered in ice. Calcite needs much warmer and wetter conditions to form than exist in the area today. Researchers dated the sample using dates from the uranium series and analyzed the oxygen composition of the formation, which was formed by flowing water.
“We wanted to produce a paleoclimate record from a period in the past when the Arctic was warmer and wetter than today, as such knowledge will hopefully allow us to improve predictions for the future,” said Gina Moseley, a researcher at the University of Innsbruck. in Austria and the paper’s lead author, Earther said in an email.
While it is difficult to exactly date an ancient piece of rock, the uranium dating allowed researchers to pinpoint the origin of the deposit between 588,000 and 549,000 years ago. The sample’s carbon-13 isotope profile and oxygen composition also indicated signs of a warmer, wetter climate. This, Moseley said, was the first time cave deposits have been used to give us a paleoclimate record for Greenland and reveals important information about what the North Pole looked like at the time.
G / O Media can receive a commission
Our previous knowledge of Greenland’s historical climate comes from samples taken from the ice sheet that covers the island. This gives us great information about what Greenland was like when that ice sheet formed, but it doesn’t help much to try and understand what came beforeThe ice cores that scientists have are limited to an interglacial warm period about 130,000 years ago. (Earlier this month, researchers said sediment in the dredging an ice core had plant fossils suggesting that Greenland was once warm enough to be ice-free.)
“Greenland’s ice core records are … focused on cold climates and the possibilities of going further back in time to warm periods are limited because the ice sheet does not tend to survive warm periods,” explained Moseley. “The new record from the caves has enabled us to tap into an earlier warm period beyond the limit of the Greenland ice cores.”
Bogdan Onac, a geologist at the University of South Florida who was not involved in the study, calls the findings “a great achievement” and “solid, carefully designed research.” He warns that more research and samples need to be taken to fully flesh out the climate profile that has begun this work.
“This research shows that you could have time across Earth’s history where temperatures were higher than present, and that was a natural trend,” he said. “Having those high temperatures means there’s probably more melting in the central part of Greenland, where you have the ice sheet. More melting means more water in the ocean. “
Learning as much as possible about the Arctic’s past is vital in predicting what its increasingly threatened future might look like. According to some estimates, the Greenland ice sheet could raise sea levels by 6.1 meters when it has completely melted, which, in addition to coastal cities worldwide, also wreak havoc on ocean currents from inject huge amounts of fresh water in the sea. Knowing that Greenland was once so much warmer than it is now is of course worrisome when you consider how we are driving climate change today with carbon dioxide (the ice sheet is now melts six times faster than in the 1980s).
“We know what’s going on in Greenland now,” said Onac. “Imagine if temperatures were three or four degrees warmer than today, how much more ice would melt. This study indicates that the [levels of] greenhouse gases were very low at the time. Today we have a greenhouse [gases] bumped into a lot. What will happen in a few centuries or millennia? ”