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- The Antarctic glaciers are melting at an unprecedented rate. This rapid loss of ice contributes to the rise in sea level.
- In a new study, scientists discovered that Thwaites Glacier, located in western Antarctica, would likely reach an irreversible melting point, after which it would lose all its ice over a 150-year period.
- If the entire Thwaites Glacier were to melt, the sea level would increase by at least 1.5 feet.
- Some experts have warned that the collapse of the Thwaites Glacier could trigger a cast iron chain reaction that would raise sea levels by an additional 8 feet.
- Visit the Business Insider home page for more stories.
In West Antarctica, a glacier the size of Florida loses ice faster than ever.
Thwaites Glacier sections retreat from 2,625 feet per year, contributing to 4% of the sea level rise in the world. This loss of ice fits into a broader trend: the entire Antarctic Ice Sheet melts almost six times faster than it was 40 years ago. In the 1980s, Antarctica lost 40 billion tons of ice a year. Over the past decade, that number has risen to an average of 252 billion tonnes per year.
Today, the authors of a new study report that over the last six years, the rate at which five Antarctic glaciers have left the ice has doubled. This makes the Thwaites Glacier a real time bomb.
Scientists reported in the Proceedings of the National Academy of Sciences magazine that the glacier was the main risk of future sea-level rise and that it was likely heading towards an irreversible melting point. .
"After reaching the critical point, the Thwaites Glacier could lose all its ice in a 150-year period," said Helen Seroussi, author of the NASA study and scientist, in a press release. "That would make sea level rise of about half a meter (1.64 feet)."
Alex Robel, another author of the study, added that if the glacier crossed this Rubicon, nothing could stop the melting of the ice, even if the Earth's temperatures stopped rising.
"It will continue on its own and it's worry," he said.
Why Thwaites Glacier can reach a tipping point
Thwaites Glacier is a large mass of snow ice that has been compressed over time. It is part of the Antarctic Ice Sheet – a large continental glacier that covers at least 20,000 square miles of land (roughly the total area of the United States and Mexico).
The Antarctic is surrounded by an ice floe of ice patches and floating ice trays that create a physical barrier between the ocean and the landlocked ice on the mainland. These floating leaves "act like a dam," had already told Business Insider Ross Virginia, director of the Institute of Arctic Studies at Dartmouth College. The barrier prevents continental ice from entering the ocean, where it melts and raises sea levels.
But with the rising temperatures of the ocean, the warmer water at the base of these ice caps melts them. This cast gives rise to cavities: a slot the size of Manhattan was discovered under the Thwaites Glacier in February. This cavity was large enough to hold 14 billion tons of ice.
Read more: The Antarctic has a cavity that is two-thirds the size of Manhattan – a sign that ice patches melt faster than expected
Each year, the portion of the Thwaites Glacier's floating ice sheet that extends into the sea grows as seawater erodes its base. For example, scientists such as Seroussi and Robel are following the Thwaites grounding line: the place where continental ice rises and floats on the water. (Think of a tongue of land that looks beyond the air of a cliff – it's the same concept for glaciers except that, instead of air, the ice is over of water.)
According to a study conducted in 2014, this grounding line would have traveled nearly 9 miles between 1992 and 2011; the more the spot moves inland, the more likely the glacier will melt.
What melts the Thwaites Glacier for sea level
With the Greenland ice cap, the Antarctic ice cap contains over 99% of the planet's fresh water.
Most of this water is frozen in masses of ice and snow up to 10,000 feet thick. But as human activities emit more greenhouse gases into the atmosphere, the oceans absorb 93% of the excess heat that they trap. Hot air and water are the cause of melting ice and glaciers at an unprecedented rate.
Seroussi said Thwaites could reach its tipping point "in the next 200 to 600 years", after which he could lose all his ice. If the Thwaites Glacier were fully melted, it would result in a global rise in sea level of 1.64 feet, according to a recent study (although another study estimated that this rise would be closer to 2 feet) .
But Thwaites also prevents its neighboring glaciers from flowing into the ocean. Other scientists therefore believe that if the Thwaites Glacier were to collapse as a whole, it could also destabilize the surrounding glaciers located on the Antarctic Ice Sheet.
If we go, they could all go – and this chain reaction would raise the sea level by an additional 8 feet.
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