Another extreme low for Antarctic sea ice signals a permanent shift

For the second year in a row, Antarctic sea ice has reached near-record low levels. This reinforces concerns that human-caused climate change has initiated a lasting “regime shift” in the amount of ice that forms in the Southern Ocean each year.

“Last year we were talking about whether Antarctic sea ice is undergoing a regime shift. Not anymore,” says Edward Doddridge at the Institute for Marine and Antarctic Studies in Australia. “Antarctica has pretty definitively answered that question for us. Now we are talking about what the impacts of that…