After a month of above normal temperatures, the weather has turned cold in the high Arctic again. Temperatures north of 80N have dropped to about -5ºC, which is near normal.
This is causing new ice to form, which is driving the 30% concentration extent numbers upward.
Similarly, ice area may have bottomed, as areas of open water near the pole begin to freeze.
PIPS hasn’t updated their maps for two days, but the most recent map shows that the southerly winds which pushed back the ice edge over the last month have also stopped.
PIPS maps show average ice thicknesss and ice volume the highest since 2007.
Modified NSIDC maps from March and late July show similar data about ice age. Multi-year ice (MYI) is defined as ice which has passed its second birthday. The blink comparator below shows actual March 2010 MYI vs. potential 2011 MYI – indicating a significant potential increase in MYI over the winter. “Potential” assumes that all end of July MYI and 1-2 year old ice survives. The actual amount of MYI next spring will be less, because of summer melt since July and winter winds which drive ice out into the North Atlantic.
Julienne Stroeve from NSIDC commented here this week :
Through the end of August, today the Arctic has the least amount of ice ages 4+ than we’ve seen in the satellite data record. There is more 2nd and 3rd year ice though than 2008, quite a bit more.
The surviving three year old ice will become four year old ice during the winter, so we can expect to see another increase in the amount of MYI and 4+ ice next spring. By all traditional definitions, this is what is known as a “recovery.”
30% extent appears to be headed back up, and it is possible that 15% extent has also bottomed.
The image below shows the 9% error in my June forecast of 5.5 million km². Ice may have bottomed out at 5.0 million km², rounded to 0.1 forecast precision.
The target below shows (possibly) final scores in ice forecasting. My errors are vs. JAXA and others are vs. NSIDC. (NSIDC reports considerably less ice than JAXA.) Each ring represents 100,000 km² error relative to the author’s chosen measurement system.
If NSIDC extent numbers are accurate, then their July forecast was also the most accurate.
The modified NSIDC map below shows ice loss over the last week.
The Arctic Oscillation is forecast to go deeply negative again, hinting at continued recovery of Arctic ice and another cold winter.
The map below shows final forecast verification for PIOMAS. Red areas are where they overpredicted ice loss, and green areas are where they underpredicted ice loss.
My forecast: Despite the apparent increase in ice age and thickness, people with an agenda to push will focus on the least meaningful of all the statistics – i.e. 15% concentration ice extent.