(Image: Alban Kakulya/Panos Pictures)
Read more: “Climate change: It’s even worse than we thought“
Not so long ago, the Arctic Ocean was covered by thick ice several years old. Even at the end of summer, more than half of the sea surface was still shrouded in ice.
As the world has warmed in the past decades, the winter refreeze has stopped compensating for the summer melt. Heat-reflecting white ice has given way to heat-absorbing dark water; snow has melted ever earlier on surrounding lands; more heat-trapping moisture has entered the atmosphere; and bigger waves and storms have assailed weakening ice. Thanks to these feedback processes, the Arctic has begun to warm twice as fast as any other region on the planet.
By the late 1990s, the extent of sea ice had fallen to . At the end of this summer, only a quarter of the Arctic Ocean was still covered in ice, a record low in modern times, and (see “Record Arctic ice loss”). What’s left is a thin layer that melts easily.
It wasn’t supposed to happen this quickly. In 2007, when the Intergovernmental Panel on Climate Change (IPCC) issued , the consensus was that the Arctic would not be ice-free in summer until the end of the century. We might have been unlucky: natural variability might have accelerated ice loss by pushing old, thick ice out of the Arctic. But climate models…
