Two major glaciers in Antarctica may be shedding ice faster now than they have at any point in the past 5,500 years, new research suggests. The melting ice could lead to more than 11 feet of global sea level rise in the next several centuries, according to a new study published in Nature Geoscience.
“Our work suggests that these vulnerable glaciers were relatively stable during the past millennia, yet their current rate of melting is accelerating and raising global sea level,” says coauthor Dylan Rood from Imperial College London in a statement.
“These currently elevated rates of ice melting may signal that those vital arteries from the heart of West Antarctic Ice Sheet (WAIS) have burst, leading to accelerating flow into the ocean that is potentially disastrous for future global sea level in a warming world.”
Scientists studied both the Thwaites Glacier (nicknamed the “Doomsday Glacier” for the potentially devastating impacts if it melts) and the neighboring Pine Island Glacier on the western side of the continent, which are both vulnerable to melting from warm water flowing underneath them.
The researchers analyzed penguin bones and seashells from ancient Antarctic beaches using radiocarbon dating to reconstruct changes in sea level relative to the coast over 5,000 years, per the statement. Scientists also studied the shifting height of the land under the changing loads of ice to see how glaciers retreated and advanced. Larger, heavier glaciers can cause the land to sink and sea level relative to the coast to rise and lighter glaciers can lead the land to rise and sea level relative to the coast to fall.
The researchers found that from about 5,000 years ago until 30 years ago, sea level relative to the coast fell at a steady rate consistent with stable glacial behavior. But in the past thirty years, relative sea level fall was almost five times lower, most likely because of rapid loss of glacial ice that led the earth to rise, per the study. On top of that, because the glaciers rest on a slope with no known highs, no topographic features will help stabilize the glacier where it is, potentially leading to runaway melting.
Last year, scientists warned that the ice shelf holding the massive, Florida-sized Thwaites Glacier in place could collapse within three to five years. Melting from the glacier is already responsible for about 4 percent of total annual global sea level rise.
“We’re watching a world that’s doing things we haven’t really seen before, because we’re pushing on the climate extremely rapidly with carbon dioxide emissions,” Ted Scambos, a glaciologist at the Cooperative Institute for Research in Environmental Sciences told Science News’ Carolyn Gramling last year. “It’s daunting.”