Despite predictions that after the 2007 record minimum ice cover, that this past summer would likely see a new record, given the amount of first year ice, we fell short by about 9% of a new record.
It has increased rapidly with a cold polar vortex the past month – with almost 80% increase since the minimum in September. Ice extent is now within the cluster of most recent years at this time of year.
It is considerably ahead of last year on the same date as can be seen from this satellite view from Cryosphere Today.
The biggest increases have been in the western Arctic and near Iceland.
The recent YEAR enhanced warm season melting of the arctic ice has precious little to do with greenhouse gases but is a cyclical phenomena related to multidecadal cycles in both the Atlantic and the Pacific. The Pacific was in its warm mode from the late 1970s to late 1990s and again briefly in the mid 2000s. The Atlantic has been in its warm mode since 1995 with a peak around 2004 and 2005. The Atlantic appears to be the most important. Warm water from the Atlantic makes its way into the arctic through the Barents Sea and the Pacific through the Bering Strait.
Last year, the University of Colorado’s National Snow and Ice Data Center (NSIDC) summarized the role of the ocean cycles very well in October 2007 in this way:
“One prominent researcher, Igor Polyakov at the University of Fairbanks, Alaska, points out that pulses of unusually warm water have been entering the Arctic Ocean from the Atlantic, which several years later are seen in the ocean north of Siberia. These pulses of water are helping to heat the upper Arctic Ocean, contributing to summer ice melt and helping to reduce winter ice growth.
Another scientist, Koji Shimada of the Japan Agency for Marine–Earth Science and Technology, reports evidence of changes in ocean circulation in the Pacific side of the Arctic Ocean. Through a complex interaction with declining sea ice, warm water entering the Arctic Ocean through Bering Strait in summer is being shunted from the Alaskan coast into the Arctic Ocean, where it fosters further ice loss. Many questions still remain to be answered, but these changes in ocean circulation may be important keys for understanding the observed loss of Arctic sea ice.”
You can see how well arctic temperatures have related to the multidecadal cycles in Atlantic (Atlantic Multidecadal Oscillation or AMO) and Pacific (Pacific Decadal Oscillation or PDO) whose warm modes are positive here. Both data sets are smoothing 11 year means. Note the warmth in the 1930s into the 1940s when similar ice thinning was observed.
Rutger’s Jennifer Frances found a similar relationship between the arctic ice and Atlantic water temperatures. I would argue with obligatory comment in the ‘abstract’ that the ocean changes are ‘consistent’ with greenhouse warming as we have seen the ocean changes are cyclical and predictable and quite natural.
Dr. Willie Soon also found a strong correlation with solar irradiance which may ultimately drive these ocean cycles of warming and cooling.
CHANGES UNDERWAY SUGGESTING ICE WILL CONTINUE TO REBOUND
As noted, the Pacific Decadal Oscillation was in its warm mode with warm water entering the arctic and producing diminishing western arctic extent from the late 1970s to the late 1990s with a rebound again in mid 2000s. Last year the North Pacific turned sharply colder.
The Atlantic peaked in 1998 (mainly tropical) and again in most of the Atlantic in 2004 and 2005 (the big hurricane seasons). It has declined since then.
With a cooling of the Pacific and a less warm North Atlantic (the net AMO+PDO) has turned negative) and a long, deep solar minimum, the ice should continue to rebound in the next few years.
Winter sea ice terrain of the Beaufort Sea (NOAA)
Read more on the arctic and Greenland here.