Yesterday, we reported a preliminary observation that the pace of Arctic spring sea ice melt was picking up. Today, most sea ice monitors now confirm this observation.
According to Cryosphere Today, sea ice area has fallen to 13.31 million square kilometers. This measure is about 55,000 square kilometers lower than yesterday and about 490,000 square kilometers below its peak last month. This daily pace of melt is a rather steep rate of loss for April and remains about 150,000 square kilometers below values for this date last year.
You can see the Cryosphere Today graph below:
NSIDC is also showing a steep rate of decline for sea ice extent. In this case, a steeper decline than the area measure over the past day, but about the same pace of decline over the last five days. Currently, we see NSIDC’s extent measure falling to 14.62 million square kilometers, about 80,000 square kilometers below yesterday’s value. This extent measure shows current year sea ice falling well below 2012 values and now at around the 4th lowest on record for this time of year. You can see this measurement in the graph below:
Finally, PIOMAS recently updated its sea ice volume monitor today. It’s currently showing sea ice volume on par with record low levels set last year and in 2011. These levels show sea ice volume currently in the range of 21,500 cubic kilometers. Though at around the same values as 2011 and 2012 overall, what this volume measure does not show is the degree to which multi-year ice (MYI) has receded and thinned. MYI is currently also near record low values. Unfortunately, the sea ice is now thicker at its edge and in regions that are almost certain to melt out as the spring and summer seasons progress and thinner near Greenland, where ice has typically sheltered from summer melt. If this observation holds, volume appears set to challenge the record low established just last year.
Various specific regions of the Arctic are currently undergoing visible thinning and breakage. In the Sea of Okhotsk, thinning and breakage of sea ice appears to be rapid, especially in the sea’s southern regions. The Bering Sea is also showing signs of thinning, with polynas opening throughout the region. North of Alaska, the sea ice is again thinning, with open water occasionally visible in the distant off-shore from Barrow Alaska over the past couple of days. Across the Arctic, polynas are also visible in the Kara and Barents Seas. Nearer to Greenland and Canada, polynas are showing up near Thule and Cape Dorset.
Overall, the Arctic remains much warmer than average for this time of year. Averages are about 5-7 degrees hotter than usual over most of the region. The hot spot, near Nuuk and Baffin Bay exceeds 15 degrees above average with Nuuk showing its second 52 degree Fahrenheit day in a row. Despite temperatures remaining above average for much of the Arctic, most of the Arctic remains under weather conditions that are below the -1.9 degree C freezing point of ocean water. That said, invasions of warmer air from the south are increasing, especially in the region near Greenland, which has been affected by much warmer temperatures than usual for almost the entire winter.
Warmer sea surface temperatures are also expanding, with most of the Arctic sea surface at around .5 degrees Celsius above average with localized hot spots. Most sea surface temps remain below the fresh water freezing point. But large and expanding areas show water temperatures above -1.9 degrees C, the freezing temperatures of ocean water.
Lastly, warmer than usual air temperatures appear to finally be having their effect on Greenland, with a small region of the extreme southern glacier showing surface melt. Melt doesn’t usually begin until mid to late May for Greenland. So we’ll have to see if this report is just sporadic or the beginning of a trend.
Overall, these conditions favor continued melt with a higher risk of melt proceeding at a more rapid pace than usual for this time of year.