Saying "climate change happened naturally in the past, and therefore human's can't cause it" is like saying "forest fires occurred naturally in the past. So there can't be arson."
Variation: Arson and camper carelessness can't cause fires, because forest fires often occurred naturally before people even existed!
Notes: Just because something occurred naturally in the past, doesn't mean people can't cause it now.
According to the National Interagency Fire Center (NIFC), in 2010 90% of fires in national forests were human-caused, vs. 10% caused by lightning strikes. However, the lightning fires burned far more acres, because they started in remote areas. See NIFC table in file link to right.
Bite Source: inspired by Haydn Washington & John Cook, Climate Change Denial (2011), p 50. Also, Richard Alley, CLEAN workshop, June 7, 2011.
Image Source: Tammy Bruce