Over the weekend, sea ice declined to new record lows hitting 3.71 million square kilometers for extent and 2.49 million square kilometers for area. In addition, PIOMAS showed sea ice volume has also reached new lows.
Trends for sea ice extent decline has been especially pronounced this year with values now 524,000 square kilometers below the record set in 2007. The rate of extent decline is still very steep for this time of year. Usually, melt rates tend to taper off by late August. But we haven’t seen a gradual slowing of melt yet.
September 15 is the average end date for sea ice melt. But with rates of decline still remaining high, melt may extent beyond the normal end date for summer melt. You can view this precipitous rate of decline in the JAXA graph below:
Looking at the sea ice from the satellite picture, we can see a large area of thick ice in the Laptev Sea surrounded by open ocean and thinning ice. It appears that, if melt continues in this region. This large chunk of ice may break off from the rest of the sheet. If this happens, it will be the second such detachment to occur this summer. Detached ice tends to melt quicker than ice connected to the larger mass. So this region may provide a final significant melt for 2012.
In a previous post here, it was estimated that sea ice area could end in a range of 2.1-2.7 million square kilometers and that extent could end in a range of 3.5-3.9 million square kilometers. Current melt is now in the middle range of both of these measures and still falling. So it would appear that end melt will likely be somewhere near the lower range of estimates. If this happens extent and area measures will have been broken by about 700,000 square kilometers by end of season.