Each year, as the sun begins to fall toward the southern sky, cold air begins to accumulate in the Arctic, bringing an end to the summer sea ice melt season. On average, this date falls on September 15th. This year, the 15th came and went. But a devastating record sea ice loss continues. A loss whose damage to the Arctic cryosphere now rivals that of 2007.
Today, Arctic sea ice extent reached new record lows for both JAXA and NSIDC. JAXA is showing sea ice extent at 3.475 million square kilometers. NSIDC is currently at 3.39 million square kilometers, also a new record low. Sea ice area reached a new record low yesterday with Cryosphere Today showing 2.234 million square kilometers.
Sea ice values are starting to now see very large departures from the record lows set in 2007 and 2011. Departures for the major measures are as follows:
JAXA Extent: -775,000 square kilometers (2007)
Cryosphere Today Area: -671,000 square kilometers (2011)
PIOMAS Volume: -400 cubic kilometers (2011)
NSIDC Extent: -780,000 square kilometers (2007)
Losses for sea ice extent are 19% below the record low level set in 2007. Losses for sea ice area are 23% below the record set in 2011. These percent losses are very close to the massive declines seen in 2007. With values now approaching 800,000 square kilometers, totals for 2012 are also now nearing the 1.1 million square kilometer losses experienced in 2007. At current rates of loss, it seems unlikely that 2012 will break much more than 800,000 square kilometers below past records. However, as the days go by, the 2012 melt season continues to surprise.
It appears that above average temperatures for this time of year are at least partially responsible for the ongoing melt. During a time when temperatures should be rapidly falling, they are, instead, remaining about level. Current average temperatures for the Arctic environment above the 80th parallel are now about -1.5 degrees Celsius. Though this temperature is below the freezing point of fresh water, salt water tends to freeze at -2 degrees Celsius. The result is that the balance of the Arctic environment is still tipped toward melting.
This sustained high temperature trend can be viewed in the graph below, provided by the Danish Meteorological Institute:
And you can see well enough that these temperatures are becoming more and more anomalous as September continues.
In addition, it is worth noting that weather conditions do not appear to particularly favor melt. In fact, we’ve just passed through a set of conditions that would have favored stabilization or freezing in a normal Arctic year. So it would seem that increasing heat content in the Arctic environment is the most likely culprit for this year’s melt.
Before I close out this blog for the evening, I’d like to let you know that I’m in Myrtle Beach, South Carolina for a one week vacation with family. We’re currently renting a beach house on the ocean and, for whatever reason, the beach directly in front of the house is terribly eroded. Only a small dune protects the house from what seems to be a hungry sea. In addition, at high tide, twice each day, the ocean waves come lapping up against the dunes. So, with each passing high tide, more and more sand is washed out to sea.
Earlier today, my wife and I went for a walk along the shore. On this particular walk we encountered not less than five homes which appear to have sustained damage from the encroaching seas. A number of other homes shelter behind sea walls. One house had an enormous pile of sand dumped in front of its property. It seemed that this sand had been deposited there by a dump truck as a measure to prevent an inflow of the encroaching seas.
A large tide pool had formed directly in front of some of these imperiled homes, replacing a normal dune line and undercutting beach walkways.
I’ll do my best to get pictures for tomorrow’s blog so you may have a visual reference. In any case, I find it somewhat ironic that a location my family chose shows such obvious effects of rising seas.