Bush's GHG confusion

Did you notice what Bush said the other day when he was asked whether he would see Al Gore's new movie?

"And in my judgment we need to set aside whether or not greenhouse gases have been caused by mankind or because of natural effects and focus on the technologies that will enable us to live better lives and at the same time protect the environment."

Read that carefully: "...whether or not greenhouse gases have been caused by mankind or because of natural effects..." (emphasis mine). It seems that Bush thinks it's the greenhouse gases that undergo significant natural fluctuations, not the climate itself. Maybe it's a minor point, but maybe it reflects some serious confusion on his part about the science behind the climate issue. Which would you guess it is?