From March 25th through June 26th, sea ice extent measures, as provided by Japan’s Arctic data system were in record low ranges. In other words, for about a quarter of a year, and according to this monitor, the Arctic Ocean and its surrounding estuaries have witnessed the lowest ice coverage ever measured for any similar period since record keeping began in the 1979.
(An amazingly long period of record low sea ice extents in JAXA’s sea ice monitor.)
This new period of extreme sea ice record lows comes during a time of continuous decadal sea ice losses. Average sea ice coverage for each successive ten year period since the 1980s during the March through June period has fallen by about 400,000 to 500,000 square kilometers. For 2016, the new record lows widened this gap to more than 2 million square kilometers — or a surface area of sea ice coverage lost roughly equivalent the size of Greenland.
Over recent days, the JAXA measure has edged slightly over the record low 2010 line for the period, ending a season-long escapade into record low ranges.
Winter/Spring Heat The Driver of New Record Lows This Year
Overall, these losses were driven by an extraordinary warming of the Arctic that has extended and intensified over these time periods. A warming that has itself been forced upon the Arctic by human greenhouse gas emissions which are, for the largest part, the result of fossil fuel burning. This year, the Arctic experienced new record warmth during a Winter that included odd periods when North Pole temperatures rose briefly above freezing.
Alaska, a microcosm of this building Arctic heat, experienced its second warmest winter on record — which was then immediately followed by its warmest spring ever recorded. Across the state, it was warmer than normal pretty much everywhere and mostly all the time.
According to this 25 Alaska city composite index (provided by Climatologist Brian Brettschnieder above) every day but two through June 30 of this year saw above normal temperatures in the related regions. Yet another pretty clear indication that there’s nothing normal about Arctic or near Arctic temperatures these days.
Closer to the 2012 Line But Still in Record Low Range
All this extreme Arctic heat during Winter and Spring was probably the major contributor to new record low sea ice extents continuing for more than three months running. However, storms over the Arctic Ocean have since moderated temperatures into closer to normal ranges for June even as these weather systems’ circulatory patterns have tended to spread the ice out. As a result, rapid rates of melt slowed somewhat into June and the extent monitor has crossed the 2010 line, coming closer to the 2012 line in the JAXA measure, while flipping back and forth over the 2012 line in other major measures (NSIDC).
(Arctic storm churns through the East Siberian and Laptev seas of the Arctic Ocean on July 1 of 2016. Sea ice measures are currently near new record lows, but a steep rate of decline will be required to challenge or break with 2012. Image source: LANCE MODIS.)
The upshot is that the sea ice state during early July doesn’t look quite as bad as it did during late May and early June. Chances for a blue ocean event in which Arctic sea ice volume exceeds an 80 percent loss since the late 1970s, in which sea ice extent falls below 1.5 million square kilometers, or sea ice area falls below 1 million square kilometers seems less likely by end Summer at this time. Such an event would now likely require some rather severe Summer weather episodes including strong highs over the Central Arctic and/or very strong late summer lows pushing heavy swells into the Central Arctic Basin. That’s not to say we shouldn’t be on the lookout for strong negative sea ice departures over the next few months — which are certainly still possible. And given the current trend, 2016 remains in a position to hit near or below 2012 records by end Summer.
NSIDC (please support public, non special interest based science by re-funding critical NSIDC satellite monitoring of the Arctic)
Hat tip to DT Lange
Hat tip to Cate
Hat tip to Colorado Bob
Hat tip to DaveW
(Disclaimer — The views and analysis expressed in this blog are my own. The related analysis is an exploration of current trends and possible future climate states informed by my own best assessment of the science. In no way is this analysis meant to be misconstrued as an absolute authoritative final word on sea ice states. For example, we cannot say with absolute certainty that any one of the following — new record lows, blue ocean events, or a failure to hit new record lows — will happen. As such, the analysis should instead be viewed as a middle-certainty forecast informed by current trends. Further scientific opinion and informed discussion on the issue is welcome.)