Interesting read, zero doubt. Shows that there was not much science being done on the subject in 1970. The sections earlier he states "... we may not be increasing the carbon dioxide content..." " the percentage of CO2 may not be greater than in was in [1920] ". A lot of "may" there, unfortunately NASA now knows better. Using NASA ice-core samples the graph below would have to spike to almost 3000 ppm before a 2 deg rise, using their 10x for 2deg basis. Unfortunately on current trajectories that is not out of the question and is ball parked for 2100 (without change), so the next generation might just see that proving old mate Leonard to be correct.
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)
