John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Despite average winds and temperatures, this year’s ice was the fourth-lowest on record.
On September 11, the sea ice in the Arctic shrank to what’s likely its smallest extent this year of 1.7 million square miles. Temperatures haven’t been balmy, and ice-breaking winds were relatively still, yet this amount was well below the historical average of 2.4 msm.
Frigid nights and the sun’s disappearance ensure the ice will begin to grow in the coming months. Yet this time next year, don’t be surprised if it hits another dismally low minimum. Just as the world’s temperatures keep going up (with this summer the hottest in known history), the ice’s area keeps going down—in fact, the nine teensiest extents in modern times have fallen in the past nine years.
Only three years on record have had lower extents: 2012 (1.3 msm), 2007 (1.6 msm), and 2011 (1.67 msm). And 2015 achieved its remarkable dwarfism without much help from the usual natural suspects. Writes NOAA:
Ten years ago, Arctic sea ice set a new record unlike anything previously observed. This year’s low is 350,000 square miles (910,000 square kilometers) below that. …
“It’s as though we have a new normal in the Arctic, with less ice than in the late 20th century,” says [National Snow and Ice Data Center] lead scientist Ted Scambos. “Climatically, this was an unspectacular year in the Arctic. There was a brief warm period in July, but overall, it wasn’t particularly warm. There was no giant late-summer storm to break up ice and lead to melt. There were no especially strong wind patterns or currents to flush out old ice. And despite that relative normalcy, we reached a sea ice minimum not seen before 2007.”
A full discussion of this year’s extent is posted over at the NSIDC. But for quick reference, here’s a graphic showing how it and other lows stack up against the average extent: