Title text: Once he had the answer, Arrhenius complained to his friends that he'd "wasted over a full year" doing tedious calculations by hand about "so trifling a matter" as hypothetical CO2 concentrations in far-off eras (quoted in Crawford, 1997).
If you asked me to estimate, I would have agreed with Randall's conclusion, but only because I would have mis-estimated both historical dates as closer to the present than they were.