The second, yellow plot, however, is the adjusted GHCN record, which is the one actually used for global temperature calculation by both GHCN and also GISS. The bottom graph shows the value of the adjustment, with blue indicating adjusting down up to 1964 and red being upwards adjustment since. The scale is a bit unclear, but the overall effect of the adjustment is to add a warming adjustment of 0.74C.
You might ask “where did the Sea Ice Years go?”, and you would be right. GHCN have pretty much adjusted these out of existence. The GHCN algorithm has obviously mistaken the sharp fall in temperatures in 1965 as some sort of aberration caused by a change of location or equipment, and therefore wiped it from the record. However it has not made the same assumption about subsequent and equally sharp rises. The result is that temperatures since 1990 appear to be consistently higher than the 1930’s and 40’s, which, according to the IMO, simply is not the case.
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GHCN’s Dodgy Adjustments In Iceland
The second, yellow plot, however, is the adjusted GHCN record, which is the one actually used for global temperature calculation by both GHCN and also GISS. The bottom graph shows the value of the adjustment, with blue indicating adjusting down up to 1964 and red being upwards adjustment since. The scale is a bit unclear, but the overall effect of the adjustment is to add a warming adjustment of 0.74C.
You might ask “where did the Sea Ice Years go?”, and you would be right. GHCN have pretty much adjusted these out of existence. The GHCN algorithm has obviously mistaken the sharp fall in temperatures in 1965 as some sort of aberration caused by a change of location or equipment, and therefore wiped it from the record. However it has not made the same assumption about subsequent and equally sharp rises. The result is that temperatures since 1990 appear to be consistently higher than the 1930’s and 40’s, which, according to the IMO, simply is not the case.
http://wattsupwiththat.com/2012/10/15/ghcns-dodgy-adjustments-in-iceland/
I was going to say the same thing, Iceland did too and that didnt stop them from taking out the chainsaw and slicing the data beyond recognition.