Tom Wigley, who is the heart of the CRU gang, introduced the 280 ppm number to the climate science community with a 1983 paper titled, “The pre-industrial carbon dioxide level.” (Climatic Change 5, 315-320). He based his work on studies by G. S. Callendar (1938) of thousands of direct measures of atmospheric CO2 beginning in 1812. Callendar rejected most of the records, including 69% of the 19th century records and only selected records that established 280 ppm as the pre-industrial level. Here’s a plot of the records with Callendar’s selections circled.
A more well founded scientific article with a historical record is as follows:
CO2.....the reality
This is really interesting stuff...
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