Arctic Sea Ice Extents Narrowly Avoid New Yearly Record Low

According to measurements from the American space agency and the University of Colorado in Boulder (UCB) National Snow and Ice Data Center (NSIDC), Arctic sea ice extents for the month of September were the second-lowest ever, narrowly avoiding setting a new all-time record low.

Preliminary analyses demonstrated this to be the case since late September, but researchers waited until all data for last month became available, before they released their newest report. Ice extents recorded in 2007 remain the lowest-ever on satellite record.

The month of September is an important indicator for sea ice health, since this is the time of year when the ice sheets reach their minimum annual extent. This time represents the height of Arctic summer, when the Sun is highest in the sky.

Ice masses will grow again over the coming months, until the height of the Arctic winter. For 6 months, there will be no Sun in the sky above these regions, allowing ices to grow to their maximum extent.

For 2011, the extremely-low extent was caused primarily by prolonged high summer temperatures, which enabled the ice to melt for longer than normal. At the same time, this year saw none of the extreme weather conditions that led to so much ice melt in 2007.

“Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still neared 2007 levels. 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,” NSIDC scientist Walt Meier explains.

“The sea ice is not only declining, the pace of the decline is becoming more drastic. The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover,” says NASA Goddard Space Flight Center (GSFC) senior scientist Joey Comiso.

Sadly, this year's values are in tune with large-scale trends. The cause for these changes is global warming, and the climate change it triggers. Over time, these events will cause the Arctic to become completely free of ice during summer months.

“The oldest and thickest ice in the Arctic continues to decline, especially in the Beaufort Sea and the Canada Basin. This appears to be an important driver for the low sea ice conditions over the past few summers,” explains scientist Julienne Stroeve, also an investigator at the NSIDC.

The lowest sea ice extent for 2011 was recorded on September 9, and gaged at only 4.33 million square kilometers (1.67 million square miles), as opposed to the average value of 4.61 million square kilometers (1.78 million square miles).