Here we go…

Just past the top of a roller coaster, as you start down the steep slope, there’s a an exhilarating and terrifying instant when you’re not moving fast yet but you can feel yourself accelerating and know the plunge is inevitable, and you just have to hope you’ll stay on the rails when you reach the bottom.

In recent weeks, there’s been a fair amount of media coverage of Arctic ice melting.   A bunch of the comments by scientists have sounded like a slow-motion version of that roller-coaster feeling – last summer and this winter, we’re seeing events in the Arctic that are ‘shocking’ and ‘disturbing’.  An article in today’s Vancouver Province notes that sea ice in the Beaufort Sea has developed unusually large cracks this winter, some over 60 miles wide.  (The Canada Ice Service has posted a remarkable day by day animation, constructed from NOAA images, that shows splits in the ice from December 7 through this week).

The inevitability part comes from the fact that sunlight falling on open water (as opposed to ice) creates a positive feedback loop:

"Arctic ice reflects close to the 95 per cent of solar radiation that hits it. Once the ice melts away, seawater absorbs the heat instead, later releasing it back to the atmosphere, a process that will speed global warming….The phenomenon is already at play in the Beaufort…..[T]he extra heat absorbed by the sea water last summer delayed the formation of new ice last fall by many weeks."

With a roller coaster, thanks to safety inspections, you can be pretty sure that, in fact, the cars will stay on the tracks.  That’s not true with climate.  It’s pretty clear that actions we take in the next few years to reduce carbon emissions can still have a significant impact on total warming, but it sure looks like a chain of inevitable consequences has already been set in motion in the Arctic.