View some more studies on global warming (or not) on the internet, search at "Planetary Temperature and Atmospheric Carbon Dioxide." Several other links share this page that you may also find of interest. Found here was that from about 600 million years ago to about 450 million years ago, CO2 level in the atmosphere varied from 7000 parts per million (ppm) to 3000 ppm. During this same period, average global temperature stayed rather constant at about 77 degrees F. During early Carboniferous Era (360 million years ago), CO2 in the atmosphere was 1500ppm but declined to about 350ppm by mid Carboniferous Era. (about 380ppm today)yet temperature for that 30 million year period remained constant at about 68 degrees F. Only in the Carboniferous