The East Antarctic Ice Sheet, long thought to be the more stable part of the ice in the land down under, way under, contains enough ice that, when melted, could raise sea levels up to 52 meters (170 feet). While the West Antarctic ice sheet (containing ice that, when melted could raise sea level to 3 – 4 meters/10 – 13 feet) may have already reached a tipping point, scientists have long thought that its eastern counterpart, the coldest place on Earth, was more resistant. Back in March 2022, a piece of Eastern Antarctica’s Conger ice shelf broke off an iceberg the size of the city of Rome. An ice shelf is the part of a glacier that floats on the water and is more vulnerable to breaking off, due to its contact with the ocean (which is warming). Ice shelves are important in that they hold back the ice on land. Once the shelves start to go, the glacial ice follows. Imagine your book shelves collapsing – it isn’t pretty!
The speedy collapse of Conger’s ice shelf followed dramatically warmer weather in Antarctica along with very low sea ice extent, which dropped to below 2 million square kilometers for the first time since satellites began measuring in 1979. This year, 2023, the sea ice extent is even lower, setting a new (low) record for sea ice extent. Less sea ice means less protection from waves battering the ice shelves and breaking them off. Unlike the Arctic, Antarctic sea ice has been relatively healthy since the 1970s – sometimes even increasing in extent – due to circumpolar winds and ocean currents isolating it from warming. But that has changed. Last week’s Science Wednesday mentioned atmospheric rivers reaching up into the Arctic. In 2022, a particularly large atmospheric river reached into the heart of Antarctica as well, followed soon after by a “dome” that prevented the heat from leaving. In the middle of the ice sheet, at a place called Vostok station, the temperature reached -0.1 Fahrenheit (-17.7 C) in the autumn. While that’s still incredibly cold, compare it with -128.6 degrees F/-89.2 C, the temperature this location has recorded in the past!
It’s uncertain whether the eastern Antarctic ice sheet has now reached a tipping point. Time will tell. But it’s quite likely that Eastern Antarctica’s ice may start affecting sea levels and the climate system over the next decades, not centuries as previously thought. With climate change accelerating and activating some tipping points sooner than later, the time really is now to halt the emissions from fossil fuels and transition to renewables. The technology is there. The rich nations, who are also most responsible for these changes (like the US), can afford to do it and should lead the way.