Farewell, Great White North.

Climate scientists, as quoted in New Scientist, have said goodbye to summer ice in the Arctic. For good:

Despite fears of runaway sea-ice loss after summer cover hit an all-time low in 2007 – opening the Northwest Passage for the first time in living memory – modelling studies based on our best understanding of ice dynamics indicated the ice cover should fully recover each winter. “They suggest that even if the ice declined a large amount in one year, it should bounce back,” said Walt Meier of the US National Snow and Ice Data Center in Boulder, Colorado.

Instead, [University of Exeter’s Tim] Lenton’s research shows a permanent alteration. If data from the last five years is anything to go by, the Arctic sea ice has not recovered from the 2007 extreme low. “The system has passed a tipping point,” he told New Scientist.

What caused the change is still unclear. Lenton speculates that the exceptional low in 2007 might have allowed the ocean to absorb so much heat that a lot of the thicker multiyear ice, which used to persist through the summer, was melted.

Some things, ice doesn’t recover from… for a long, long time.

Now, they’re afraid that the melting ice will trigger underwater mudslides in Greenland, which will release huge clouds of methane and tsunamis. So we’ve got something to look forward to.