Scientists studying the ancient history of the Antarctic ice sheet have found evidence of an “extreme” melting event that caused sea levels to rise sharply,media New Atlas reported. Scientists see the melting event, which took place more than 100,000 years ago, as a cautionary tale of climate change. The study was led by scientists at the University of New South Wales in Sydney, Australia, who set out to study the behavior of the West Antarctic ice sheet during the “last interglacle ice age” that occurred about 129,000 to 116,000 years ago.
During that period, the surface water of the ocean warmed by 2 degrees Celsius, an ideal time to study how global warming affects sea levels and melting ice in the region.
To do this, the team used the so-called “blue ice zone”, which is formed by strong winds that blow up layers of snow and erode exposed ice. When this happens, it provides scientists with a time capsule and a window into the history of the ice sheet.
Professor Chris Turney, who led the research team, said: “We don’t have to drill a few kilometres on the ice, we just have to cross a blue ice zone and then cross thousands of years ago. By collecting ice samples from the surface, we can reconstruct what happened in this precious environment in the past. “
The isotope measurements of the samples allowed the team to piece together the history of the ice sheet and, in doing so, noticed a recorded gap, which occurred just before the last interglacle ice age. This gap coincides with an extreme rise in sea level that occurs around the same time, suggesting that the ice has melted into the surrounding waters. This conclusion can be supported by examining the DNA of fine volcanic ash and trace gases in the sample, as well as bacteria trapped in ice.
Some scientists believe that at some point during the last interglacle ice age, the global average sea level is 6 to 9 meters (20 to 30 feet) higher than it is now, and some suspect they could be as high as 11 meters (36 feet). Many factors are thought to contribute to this phenomenon, including melting glaciers, thawing of Greenland’s ice sheet and the expansion of the oceans due to warming of the sea. The new study shows that West Antarctica plays an important role, unilaterally causing sea levels to rise by more than 3 meters (9.8 feet), the team said.
Professor Turney said: “We now have some key evidence that Antarctica is melting and contributing to a large part of sea level rise. “Scientists are concerned about the future that the Antarctic ice sheet seems more susceptible to warm waters. This is because it is located on the seabed, not on the ground, like the East Antarctic ice sheet, and the sea fills the cavity below it, melting the ice from below.
To explore how the Earth would develop if it continued to warm as expected, the team used the data they collected to model the simulations and study the effects of the ice shelf, which clings to the surface and slows the flow of ice from the continent. Their results suggest that sea levels will increase by 3.8 meters (12.5 feet) in the first 1,000 years before temperatures rise by 2 degrees Celsius, and that the ice shelf will completely collapse in the first 200 years. The team believes this could trigger a series of irreversible events, including the melting of the East Antarctic ice sheet, which raises sea levels.
Professor Christopher Fogwill, of Keele University in the UK and co-author of the study, said: “Our research suggests that the Antarctic ice sheet may be close to a tipping point, which, once passed, may lead us to commit to a rapid rise in sea levels over the next few thousand years. This highlights the urgent need to reduce and control greenhouse gas emissions that contribute to today’s warming. “
The researchers hope to start here, using their technique to create a larger network to see how other parts of the ice sheet are affected and how quickly they melt.
“We only tested one site, so we don’t know if this is the first area of Antarctica to melt or if it’s relatively late,” Turney said. As the planet warms, it remains a huge question of how these changes in Antarctica will affect the rest of the world in the future. Testing other locations will give us a better understanding of the areas we really need to monitor as the earth continues to warm. “
The study was published in the Proceedings of the National Academy of Sciences.