A new study suggests that Antarctica’s ice shelves may be melting faster than previously believed, which is causing sea levels to rise at a more rapid pace and accelerating the dangers of climate change.
The study, published in the journal “Science Advances” on Aug. 12, was conducted by Caltech and Jet Propulsion Laboratory researchers. It’s based on a model that accounts for a narrow ocean current, which runs along the Antarctic coast.
The current’s flow patterns show how freshwater, which has melted from the ice shelves, can trap dense warm ocean water at the base of the ice, intensifying heat and, therefore, causing more ice to melt.
“If this mechanism that we’ve been studying is active in the real world, it may mean that ice shelf melt rates are 20 to 40 percent higher than the predictions in global climate models, which typically cannot simulate these strong currents near the Antarctic coast,” Andy Thompson, one of the researchers and professor of environmental science and engineering, said in a Caltech news release.
According to the release, “ice shelves are outcroppings of the Antarctic ice sheet, found where the ice juts out from land and floats on top of the ocean.”
Several hundred metres thick, the shelves offer a protective buffer for the mainland ice, blocking the whole ice sheet from flowing into the ocean.
“A warming atmosphere and warming oceans caused by climate change are increasing the speed at which these ice shelves are melting,” says the news release, which is “threatening their ability to hold back the flow of the ice sheet.”
The study was led by senior research scientist Mar Flexas, who said their climate model assessed a current which is often overlooked by other researchers: the Antarctic Coastal Current, which runs counter-clockwise around the entire Antarctic continent, and is often considered too small to offer relevant data.
“Large global climate models don’t include this coastal current because it’s very narrow—only about 20 kilometres wide, while most climate models only capture currents that are 100 kilometres across or larger,” Flexas said in the release. “So, there is a potential for those models to not represent future melt rates very accurately.”
Increased meltwater can escalate melting at West Antarctic ice shelves thousands of kilometres away from the peninsula, the research suggests.
The release says that “this remote warming mechanism may be part of the reason that the loss of volume from West Antarctic ice shelves has accelerated in recent decades.”
“There are aspects of the climate system that we are still discovering,” Thompson said in the release. “As we’ve made progress in our ability to model interactions between the ocean, ice shelves, and atmosphere, we’re able to make more accurate predictions with better constraints on uncertainty. We may need to revisit some of the predictions of sea level rise in the next decades or century—that’s work that we’ll do going forward.”