Lower than low: Arctic sea ice reaches a new low, says National Snow and Ice Data Center
"Few of us were prepared for how rapidly the changes would actually occur”
Arctic sea ice cover likely melted to its minimum extent for the year on Sept. 16, say scientists at the National Snow and Ice Data Center.
That’s when sea ice extent fell to 3.41 million square kilometrres.
This is now the lowest summer minimum extent ever recorded during the 33-year satellite record of ice cover in the Arctic.
“We are now in uncharted territory,” said Mark Serreze, who is director of the Colorado-based NSIDC. “While we’ve long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur.”
Arctic sea ice cover grows each winter as the sun sets for several months, and shrinks each summer as the sun rises higher in the northern sky.
Each year, the Arctic sea ice reaches its minimum extent in September.
This year’s minimum follows a record-breaking summer of low sea ice extents in the Arctic, the data center said.
Sea ice extent fell to 4.10 million sq. km. on Aug. 26, breaking the lowest extent on record set on Sept. 18, 2007 of 4.17 million sq. km.
On Sept. 4, it fell below four million sq. km. — another first in the 33-year satellite record, the data centre said.
“The strong late season decline is indicative of how thin the ice cover is,” said NSIDC scientist Walt Meier. “Ice has to be quite thin to continue melting away as the sun goes down and fall approaches.”
NSIDC scientists say they have observed fundamental changes in the Arctic’s sea ice cover. The Arctic used to be dominated by multiyear ice, or ice that survived through several years. Lately, the Arctic is increasingly characterized by seasonal ice cover and large areas which are now prone to completely melt away in summer.
This year’s minimum will be nearly 50 percent lower than the 1979 to 2000 average.
NSIDC lead scientist Ted Scambos said that thinning ice, along with early loss of snow, are rapidly warming the Arctic. “But a wider impact may come from the increased heat and moisture the warmer Arctic is adding to the climate system,” he said. “This will gradually affect climate in the areas where we live,” he added. “We have a less polar pole—and so there will be more variations and extremes.”
NSIDC scientist Julienne Stroeve said “recent climate models suggest that ice-free conditions may happen before 2050, though the observed rate of decline remains faster than many of the models are able to capture.”
Serreze said that “while lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, twenty years from now from now in August you might be able to take a ship right across the Arctic Ocean.”