- Arctic sea ice from March 7 to Sept. 9, 2011, as measured by the Aqua satellite. The yellow line depicts the 30-year average extent of the ice; the red line is the Northwest Passage shipping lane. (NASA)
The sea ice capping the Arctic Ocean is melting away much faster and in more critical areas than initially predicted, and could dissolve entirely into tepid water earlier than 2100, a group of scientists said today.
The sea ice, which typically reaches its lowest extent each September, was the second smallest in known history this past month, according to researchers from NASA and the National Snow and Ice Data Center at the University of Colorado in Boulder. You can see how far the white ice has receded in the above map. (Larger, and here's a great movie of the cap from March 7 to Sept. 9.) The yellow line represents the 30-year average September extent, and the red line is the Northwest Passage, a shipping route that is becoming increasingly viable thanks to ice loss.
The teeny-tiny ice cap in 2007 still holds the record for lowest-ever extent, but that's no great comfort, because there were mitigating factors causing that incredible melt. Says the space agency:
The near-record ice-melt [of Sept. 2011] followed higher-than-average summer temperatures, but without the unusual weather conditions that contributed to the extreme melt of 2007. "Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels," said NSIDC scientist Walt Meier. "This probably reflects loss of multiyear ice in the Beaufort and Chukchi seas as well as other factors that are making the ice more vulnerable."
Scientists have been tracking the incredible shrinking ice cap with sensitive satellite instruments since the late '70s. The September cap has shrunk an average of 12 percent each decade, a fact that "scientists attribute largely to warming temperatures caused by climate change," according to NASA. (Here's the full story.)
However, models that were created years ago to forecast the loss of Arctic ice were apparently low-balling the magnitude of the problem. Here's Joey Comiso, senior scientist at NASA's Goddard Space Flight Center in Maryland:
"The sea ice is not only declining, the pace of the decline is becoming more drastic," Comiso said. "The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover."
Before, the thinking among many climatologists was that the sea ice could be all gone by 2100. Now it looks like polar explorers and polar bears might not have anything to stand on sometime earlier than that. How early? We'll just have to wait and see!