I was under the assumption that we cycle through climate changes constantly and I could make a good argument based on the history of ice-ages.
Um... 'Round these parts this is, like, the coolest summer I can remember. It's July and 71 degrees during the day. WTF?
Yep. Prolly has to do with the fact that plantlife grabs the carbon out of the air.
Y'see, when the Earth is warm and the atmosphere is full of carbon dioxide (a greenhouse gas), forests expand and glaciers recede. The expanding forests leave excess oxygen in the atmosphere and the planet begins to cool. The forests recede and the glaciers expand. This, of course, results in a surplus of unused carbon dioxide which then warms the planet and the glaciers recede and the forests expand. And so on and so on and so on...