Wednesday, September 16, 2015

Arctic Sea Ice Hits Annual Minimum, 4th Lowest on Record

The Northwest Passage of the Arctic as seen on Aug. 31, 2015. While not completely ice-free it was considered open for several weeks this summer, which is happening more often and for longer with Arctic warming. (Credit: NASA) Click to Enlarge.
Arctic sea ice appears to have reached its annual summer low point, and, as expected, it is the fourth lowest in the four decades of record-keeping, the National Snow and Ice Data Center in Boulder, Colo., announced Tuesday.

While summer ice melt is part of the normal seasonal sea ice cycle, the record lows reached in recent years are a clear sign of the warming-driven decline in Arctic sea ice.  All 10 of the lowest sea ice extents on record have occurred since 2005.

The decline in the area of the Arctic Ocean covered by sea ice, as well as the thinning of this ice, has impacts on the overall Arctic environment.  It is imperiling native communities as ocean waters increasingly eat away at coastlines, as well as Arctic species that depend on the sea ice to help them hunt prey.  The disappearance of the ice is also leading to increased shipping traffic and oil exploration that could have major economic and ecological impacts.

The annual minimum comes as NASA data reveals that August 2015 was the second warmest August on record, increasing the odds that the year will be the warmest on record globally.

Over the summer, sea ice melt had periods where it surged ahead and then leveled off.  The decline was rapid in late July and remained steady through August before bottoming out in mid-September.

This year’s minimum extent appears to have occurred on Sept. 11, when it reached 1.7 million square miles, which is about 700,000 square miles below the 1981-2010 average.  The lowest extent on record, set in 2012, reached 1.32 million square miles.

Just how low the annual minimum goes is not only influenced by the overall warming trend, but also by summer weather systems.  For example, the 2012 record minimum came during the remarkable summer melt season of 2012 and was fueled in part by summer storms that moved ice into warm waters.

Read more at Arctic Sea Ice Hits Annual Minimum, 4th Lowest on Record

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