The evolution of the present CO2 desert

After yesterday’s article on the carboniferous desert (350-250million years ago), I’ve added a section to the article suggesting why we had the second drop in CO2 from around 150million years ago to the current “2nd CO2 desert”.
See: http://scottishsceptic.uk/2015/06/25/lignin-and-the-carboniferous-co2-drop/