Increasing geological evidence suggests that the Arctic was once much warmer than it is today, which means big problems as we continue to pump greenhouse gases into the atmosphere with abandonment. The latest development is a study published Wednesday in Science Advances, which uses geological deposits of caves to deduce that the region was at least 6.3 degrees Fahrenheit (3.5 degrees Celsius) warmer than today, just over 500,000 years ago.
To try to understand what the Arctic past might have looked like, the researchers looked at a 4.73-inch (12-centimeter-thick) calcite mineral deposit they found in a cave in northeast Greenland. Even though Arctic things heat up quickly, it is still mostly cold and covered in ice. Calcite needs much warmer and wetter conditions to form than exists in the area today. The researchers dated the sample using uranium series dating and analyzed the oxygen composition of the formation, which was formed by the flow of water.
“We set out to produce a paleoclimatic record from a time when the Arctic was warmer and wetter than it is today, because such knowledge will hopefully allow us to improve our forecasts for the future,” said Gina Moseley. researcher at the University of Innsbruck in Austria and lead author of the paper, they told Earther in an email.
Although it is difficult to accurately date an old piece of stone, uranium dating has allowed researchers to identify the origin of the deposit in a period between 588,000 and 549,000 years ago. The carbon-13 isotope profile of the sample and the oxygen composition also showed signs of a warmer and wetter climate. This, Moseley said, marked the first time cave deposits were used to give us a paleoclimatic record for Greenland and reveals some important information about what the Arctic might have looked like then.
G / O Media may 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 wonderful information about what Greenland was like when the ice sheet formed, but it’s not very helpful to try to understand what came before. Scientists’ ice cores are limited to a warm interglacial period about 130,000 years ago. (Earlier this month, researchers said the sediments found in dear ice core had plant fossils suggesting that Greenland was once warm enough to be ice-free.)
“Recordings of the Greenland ice core are … biased in cold climates and the possibility of extending over time to warm periods is limited, as the ice sheet does not tend to survive warm periods,” Moseley explained. “The new cave record has allowed us to enter a warm period beyond the boundaries of Greenland’s ice cores.”
Bogdan Onac, a geologist at the University of South Florida who was not involved in the study, considers the findings “a great achievement” and “solid, carefully researched.” He warns that more research and samples must be taken to fully realize the climate profile started by this work.
“This research highlights the fact that you may have time over the history of the Earth, where temperatures have been higher than they are today, and this has been a natural trend,” he said. “Having those high temperatures means more melting is probably in the central part of Greenland, where you have the ice sheet. More melting means more water in the ocean. ”
Discovering the Arctic’s past as much as possible is of huge importance in predicting what its increasingly dangerous future might look like. Some estimates estimate that Greenland’s ice sheet could rise to sea level by 6.1 meters if completely melted, which, in addition to affecting coastal cities around the world, would wreak havoc on ocean currents injecting huge amounts of fresh water in the sea. Knowing that Greenland was once much warmer than it was naturally today, it is worrying given how we overcharge climate change today with carbon dioxide (the ice sheet is now melting six times faster than it was in the 1980s).
“We know what’s happening in Greenland now,” Onac said. “Imagine temperatures that were three or four degrees warmer than today, how much ice would melt. This study points out that [levels of] greenhouse gases at that time were very low. Today we have a greenhouse [gases] hit a lot. What will happen in a few centuries or millennia? ”