A new study says in the past 30 years, two major glaciers in Antarctica have been losing ice at their fastest rates over the last 5,500 years and can contribute as much as 3.4 metres of global sea level rise.
The study, published June 9 in the journal Nature Geoscience and led by researchers from the University of Maine and the British Antarctic Survey, looked at the rate of sea level change near the West Antarctic Ice Sheet as an indirect way of gauging how fast the glaciers are melting.
The Thwaites and Pine Island glaciers in the West Antarctic Ice Sheet have areas of 192,000 square kilometres and 162,300 square kilometres, respectively. The Thwaites Glacier, in particular, has been nicknamed the Doomsday Glacier by climate scientists, given its potential to cause significant changes in global sea level if it melts.
The researchers examined seashells and penguin bones on the remnants of old Antarctic beaches in the area using a process called radiocarbon dating, which estimates how old the shells and bones are and how long they've sat above the local sea level and how old these beaches are.
Understanding when these beaches first appeared allow researchers to reconstruct the change in sea level over time.
Researchers say there's an inverse relationship between the local sea levels in the Antarctic and the global sea levels. Heavy glaciers sitting on the land push down towards the earth's surface, which is known as crustal loading. When the glaciers melt, the land can rise and the local sea level falls.
"Relative sea-level change allows you to see large-scale crustal loading and unloading by ice. For example, glacier readvance, which would result in crustal loading, would slow the rate of relative sea-level fall or potentially even cause submergence of the land below sea level," lead author Brenda Hall said in a news release published last Thursday.
At the current rate of melting, the researchers say the glaciers could contribute to as much as 3.4 metres of global sea level rise over the next several centuries. Study co-author Dylan Rood said this flow into the ocean could be "potentially disastrous for future global sea level in a warming world."
"Although these vulnerable glaciers were relatively stable during the past few millennia, their current rate of retreat is accelerating and already raising global sea level," Rood said in the news release. "We now urgently need to work out if it's too late to stop the bleeding."
