One of the pillars of the anthrpogenic global warming theorists is that CO2 levels were fairly  constant until fossil fuel burning changed everything. The Astute Bloggers point us to a paper published in the journal Energy and Environment, demonstrating that CO2 levels have varied widely. The unseemly rush to declare the "science" of global warming "settled" is going to weigh heavily on the reputations of many in the scientific, journalistic, and political worlds.