It is unlikely that the world’s view of Arctic sea ice will ever be the same after the 2012 melt season. What was revealed was a thin film of fragile ice now at the mercy of rising temperatures and an ever-increasing number of forces that could result in ice melt, break-up, and scattering.
So even as seasonal re-freeze begins there is much inherent in this dynamic set of Arctic systems changes to take account of. In fact, it is important that these trends be tracked as we enter an age of uncertainty, instability, and messy transition. Currently, the story in the Arctic is shifting from record lows in sea ice extent and area, to the difference between past ‘mean’ values of sea ice area and what current observations can tell us.
It is important to note that all measures show sea ice area and extent below the past record low set for this date. And the relatively slow re-freeze of the Arctic sea ice combined with this very low value raises the possibility that a new record will be set. That record is defined as sea ice anomaly — a departure from an established average of sea ice area over the period of 1979-2008.
Approaching a New Record Anomaly
The above graph, provided by Cryosphere Today, shows not only the current area of Arctic sea ice, it also shows the difference between now and the 1979-2008 mean. It is important to note that this value is somewhat skewed due to the fact that sea ice has been in continuous decline ever since the satellite record began. So the 1979-2008 ‘mean’ averages not a base-line period of relatively stable sea ice. It instead averages a period of melt.
All that said, departures below this ‘mean’ are currently at 2.482 million square kilometers. This value is very close to the record set in 2007 of 2.635 million square kilometers below the mean. A breaking of this record would be even more significant due to the fact that the current ‘mean’ includes the two very low years of 2007 and 2008.
High Temperatures as Primary Driver
Looking at conditions in the Arctic, weather patterns would tend to indicate a greater spreading out of the sea ice and a faster re-freeze. Checking this value is a cloudy and stormy overall Arctic environment which would tend to trap heat. As this year has shown that traditional weather links to re-freeze have been obliterated by increasing heat energy in the Arctic system, a look at weather patterns alone can’t provide us with much in the way of reasonable assurance. So heat itself and heat retention becomes much more important.
A view of the graph below shows us that Arctic temperatures above the 80th parallel are currently well above normal — in the range of about 10 degrees Fahrenheit above what is considered average for this time of year.
The ‘mean’ averages — shown by the green line — are produced from temperature measurements from 1958-2002. Again, as with sea ice anomaly, this ‘mean’ measures a period of rising temperatures. So it is not a stable base-line. Departures from 1960s values are, therefore, likely 50% higher than the current departure from the ‘mean.’
In any case, a 10 degree F departure from the 1958-2002 mean shows a lot of heat energy still retained in the Arctic and generally failing to bleed off at the typical freezing season’s rate. You can see this delay by looking at the slope of the 2012 temperature line, which is no-where near as steep as the slope of the ‘mean’ temperature line.
Another way to view Arctic temperature is via the surface temperature anomaly map provided by NOAA’s Earth Systems Research Laboratory:
The above map shows that much of the Arctic is currently in the range of 3-11 degrees C (5-19 degrees F) above the 1985-1996 mean. It is worth noting that the 1985-1996 mean, though far warmer than the 1960s, does not include the series of record hot years of 1998-2002.
These very high temperatures show that a massive amount of heat is still being retained in the Arctic. So there is a high potential for the record anomaly set in 2007 to be broken over the next couple of weeks.