I have a friend named Doris who argues on good authority that the single biggest cause of global warming is menopause.
The science is crystal clear: we humans are the primary cause of global warming and we face a bleak future if we fail to act quickly.
The question of whether or to what extent human activities are causing global warming is not a matter of ideology let alone of belief. The issue is simply one of risk management.
Romney has become reluctant to say that human activity causes global warming and even in his greener days he was always somewhat cagey about which remedies he'd support.