regarding the article:
I can see that skepticalscience appears satisfied with the DMI data when you use the full year data – so what causes the summer temperature mismatch north of 80N between GISS data and DMI data?
Let’s refresh our memories:
A few days after the WUWT article, the DMI “melt season” was over and the final version of updated DMI 80-90N DMI summer (melt season) temperatures appears as follows:
- Yes, the DMI melt season temperatures 80-90N in 2010 hit an all time low temperature record of just near +0,34 Celsius thus once again confirming the cold trend that started around 1991.
DMI trend summer 1991-2009: COOLING
GISS 80-90N temperatures june and july mostly projected up to 1200 km.
GISS june, july trend 1991-2009: WARMING
This does not make the GISS temperature projection method look good.
I can’t see how the writing at Skepticalscience.com should change that. I also showed other examples of problems with the GISS temperatures projected 1200 km over the ocean not really addressed in the skepticalscience article.
Normally when examining ice extent, believers of the global warming hypothesis mostly focus on the summer melt period. But now when a data source (the best data source for 80N-90N) shows temperatures for the melt period to be cooling of the area 80-90N, then we should look at the whole year. OK, lets then focus on the FULL year ice extent for the FULL globe based on Cryosphere data:
The 2010 column (an early prognosis) so far comes in number five since year 2000. That is, the fifth smallest global sea ice extent since year 2000.
So to begin with, the anomalies of global sea ice extent for 2008-10 appears to be just 0,3-5 mio sq km under normal.
However, Cryosphere in January 2007 made a Correction/reduction in Arctic sea ice data:
Here we see that the whole level of Arctic sea ice after year 2000 has been corrected down by Cryosphere with around 0,3 – 1,0 mio sq km. So this correction itself is perhaps large enough to fully account for the “missing” sea ice extent 2008-10. The strong La Nina cooling 1999-2001 is clearly reflected in the CT 2006 data, but not easy seen in the CT 2010 data.
So, without the Cryosphere correction done in January 2007, the sea ice anomalies 2008-2010 would have been zero or positive.
In my archives, I found this compare of arctic summer ice extents showing, that CT´s Arctic summer ice decline is over 1 mio sq km larger in 2007 than other data sources:
(Im not sure who collected these data.)
This indicates that the essential Cryosphere Jan 2007 correction may be an outlier.
Similar to the uncorrected CT data are the gridded NSIDC data presented by Jeff Id:
Again, the years 2008-2010 is not really supporting any downward trend, although the entire period 1978-2009 shows decline using a banal flat trend.
For both CT data and Jeff Id´s NSIDC data presentation we see that its in fact it is mostly the years 2005, 2006 and 2007 that shows a large dip in global sea ice extent. Take away those years, and where is the decadal declining trend?
When Jeff Id Zooms in on the years after 1995, it becomes clear, that the 3 years (2005-7) is responsible for downward trends if we use the banal flat trend argumentation for global ice extent:
Link to Jeff Id´s article: