As the Arctic slipped into the half-darkness of autumn last year, it seemed to enter the Twilight Zone. In the span of a few months, all manner of strange things happened.
The cap of sea ice covering the Arctic Ocean started to shrink when it should have been growing. Temperatures at the North Pole soared more than 20 °C above normal at times. And polar bears prowling the shorelines of Hudson Bay had a record number of run-ins with people while waiting for the water to freeze over.
It was a stark illustration of just how quickly climate change is reshaping the far north. And if last autumn was bizarre, it’s the summers that have really got scientists worried. As early as 2030, researchers say, the Arctic Ocean could lose essentially all of its ice during the warmest months of the year — a radical transformation that would upend Arctic ecosystems and disrupt many northern communities.
Atmospheric scientist Jennifer Francis has for five years propounded a widely discussed theory about the rapidly warming Arctic and global weather: Rising temperatures in the Arctic, closely intertwined with the loss of sea ice, are changing the shape of the jet stream and altering the weather of the Northern Hemisphere.
Some climate scientists and meteorologists have embraced her theory, while others have adopted a wait-and-see attitude. But this year’s freakishly warm Arctic weather is lending credence to her hypothesis that a lessening of the temperature difference between the Arctic and the mid-latitudes is causing the jet stream to wobble, allowing warm air to flood into the north polar regions and sending frigid air southward into parts of Asia. More profound changes are in store as the Arctic continues to warm, says Francis, a research professor at Rutgers University.