People were so dumb back in 1960. Hansen has been able to go back in time and retroactively prove that very little warming occurred in Spitzbergen between 1910 and 1960.
Data.GISS: GISS Surface Temperature Analysis
Hansen used to be dumb too. His older data confirmed about 8C warming during that period.
Data.GISS: GISS Surface Temperature Analysis
But Hansen has since gotten much smarter and has been able to turn that huge 1910-1960 warming trend into a cooling trend. His latest perversion of the graph is shown below.
Hansen is a pretty retroactively smart guy!
I used to think Hansen data was akin to astrological predictions, aka for entertainment purposes only. I may be mistaken.
Perhaps Hansen should be celebrated as one of the most successful fiction authors belonging to the genre of Alternate History (AH), also known as allohistory.
The ubiquitously dead-certain Wikipedia has a description of this type of fictional prose:
“In writing an alternate history, the author makes the conscious choice to change something in our past. According to Steven H Silver, alternate history requires three things:
1) the story must have a point of divergence from the history of our world prior to the time at which the author is writing,
2) a change that would alter history as it is known, and
3) an examination of the ramifications of that change.”
Both given graphs indicate that the 1910s showed a deep temperature drop, culminating in 1917. Actually, the winter 1918/19 brought about a big trend change, causing a two decade long Arctic warming that lasted in the USA until 1933 and in Europe until 1939. For the winter half-year from 1920-1939 see here: http://www.arctic-heats-up.com/pdf/3_1.pdf
A further overview is here: http://www.seaclimate.com/i/image/images/buch/big/i-3_TM14.pn, discussing the causation. More in “Chapter I; Warming before Cooling – The trace to the First World War” here: http://www.seaclimate.com/i/i.html