The web archive never forgets.
In 1997, GISS showed that about three-fourths of global warming occurred prior to 1940. In other words, global warming started before CO2 started rising significantly, and recent global warming coincided exactly with the PDO shift in 1976.
Archived here : http://www.giss.nasa.gov/Data/GISTEMP/GLB.Ts.txt
But it is worse than it seems. It turns out that 1940 to 1970 global cooling was real, before they deep-sixed it.
The next graph shows how GISS has altered the data since 1997.
Current data here : data.giss.nasa.gov/gistemp/graphs_v3/Fig.A.txt
Now we know why GISS doesn’t keep their old data around. It doesn’t support global warming theory.