Buried in my basement is a 1974 copy of Encyclopaedia Brittanica. Tipped off by an article on Jo Nova and Watts Up With That about National Geographic 1976 showing a much different temperature graph in 1976 than what CRU publishes, I thought I would dig out Brittanica 1974 and compare. Here is the graph from National Geographic 1976 with CRU temperature data superimposed. It is easy to see that they begin to diverge about 1950 or so despite (supposedly) being drawn from the same historical data:
Encyclopaedia Britannica 1974 also has some historical temperature graphs. Theirs run from 1880 to 1960, but are broken up by latitude and are in degrees Fahrenheit. Only a brief perusal reveals some very interesting results:
Interestingly, not one of the latitude bands shows an increase in temperature data from 1950 to 1960 while CRU data does. The thought crossed my mind when I saw the article about National Geographic that there was some plausible explanation. National Geo has a good reputation, but it is plausible that they made a mistake. That their graph agrees with Brittanica’s, an organization famous for meticulous checking of sources, calls into question what data CRU used and how they used it to arrive at their graph.