re: try "On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground", Philosophical Magazine 1896(41): 237-76)
"Arrhenius did very little research in the fields of climatology and geophysics, and considered any work in these fields a hobby.
...
Arrhenius argued that variations in trace constituents—namely carbon dioxide—of the atmosphere could greatly influence the heat budget of the Earth. Using the best data available to him (and making many assumptions and estimates that were necessary), he performed a series of calculations on the temperature effects of increasing and decreasing amounts of carbon dioxide in the Earth's atmosphere."
http://earthobservatory.nasa.gov/Features/Arrhenius/arrhenius_2.php