We have had a lot of discussion recently about the loss of 5+ year old ice in the Arctic. Most of the older ice loss occurred between 1988 and 1996 – during a period of normal global temperatures.
From http://nsidc.org/arcticseaicenews/2007.html
1988 (5+ ice is red)
There was very little older ice loss between 1996 and the end of the “record 2007 melt season”
2007
http://www.woodfortrees.org/plot/uah/from:1988/to:1996/plot/uah/from:1988/to:1996/trend
Conclusion : There is a story here, but it is not the one people are chasing after. 2007 is not the story. What happened between 1988 and 1996?
The story is that the Arctic Sea Ice is subject to natural cycles and there is nothing we can do about it.
Given what I am seeing with La Ninas that seem progressively stronger and more like
ah, the last cold PDO shift (1950-1977/78) I agree with Bastardi’s “Two steps forward,
one step back” in regard to ice redevelopment..
“Average January sea ice thickness increased during 1982-88 in most regions of the Arctic (+7.6 ± 0.9 cm yr-1), decreased through 1996 Arctic-wide (-6.1 ± 1.2 cm yr-1), then modestly increased through 2003 mostly in the central Arctic (+2.1 ± 0.6 cm yr-1).”
Belchansky 2008 http://cat.inist.fr/?aModele=afficheN&cpsidt=20140434
Tshudi 2010 (http://soa.arcus.org/sites/soa.arcus.org/files/sessions/2-1-observations-arctic-change/pdf/2-1-3-tschudi-mark.pdf) shows the drop in overall multiyear ice in the first half of the 90`s. And a new drop since 2005:
http://diablobanquisa.files.wordpress.com/2010/06/arctic_ice_volume-e1275496035553.jpg?w=640
From 2005 to 2008 a 40% drop in the overall MYI area in the arctic.
http://diablobanquisa.files.wordpress.com/2010/06/declaine_in_arctic_ocean_multiyear_sea_ice_coverage324873main_kwokfig4_full_610x470-e1275496629836.jpg
The extent of MYI will triple over the next few weeks.
What happened between 1988 and 1996?
A sharp shift in the AO/NAO index, from the negative to the positive state.
http://diablobanquisa.files.wordpress.com/2010/03/climate-ao-e1268153207959.png
This may go to show how unimportant 5+ year ice is in the scheme of things, as 1996 was the fifth highest minimum on record according to CT’s area numbers (at 5238185 km^2, only 1979, 1980, 1986, and 1987 were higher).
-Scott
And the highest september monthly mean sea ice extent according NSIDC.