World’s largest iceberg breaks off an Antarctica ice shelf

A giant slab of ice almost twice the size of the Australian Capital Territory has sheared off from the frozen edge of Antarctica into the Weddell Sea, becoming the largest iceberg currently afloat in the world, the European Space Agency says.

Iceberg A-76 calved from the western side of the Ronne Ice Shelf in Antarctica and is now floating on the Weddell Sea, the European Space Agency said. It measures around 170 kilometers (105 miles) long and 25 kilometers (15 miles) wide.

While A-76 is the largest iceberg in the world at the moment, it wouldn’t make the pantheon of the 10 biggest icebergs in history.

“In the grand context of things this is not humungous. Of course it’s an evolution in the ice shelf,” says Mark Drinkwater of the European Space Agency.

Drinkwater says that the Ronne ice shelf is in a fairly “steady state” where it expands after losing iceberg like this. One of its biggest calving events was in 1986, with icebergs totalling 11,000 square kilometres breaking off, followed by smaller ones in 1998, 2000 and 2015.

The Antarctica ice sheet is warming faster than the rest of the planet, causing melting of snow and ice covers as well as the retreat of glaciers, especially around the Weddell Sea. As glaciers retreat, chunks of ice break off and float adrift until they break apart or crash into land.

Last year, currents took iceberg A-68A, the world’s largest at the time, from Antarctica to the coast of the South Georgia Island. Scientists feared the berg would collide with an island that’s a breeding ground for sea lions and penguins, but it ended up splitting and breaking into pieces instead.

Average sea levels have risen about nine inches since 1880, and about a quarter of that increase comes from ice melting in the Greenland and Antarctica ice sheets, along with land-based glaciers elsewhere, according to a study published in Nature earlier this month.