Early in the 2012 presidential campaign, in June 2011, Romney said, "I don't speak for the scientific community, of course, but I believe the world's getting warmer. I can't prove that, but I believe based on what I read that the world is getting warmer. And number two, I believe that humans contribute to that. I don't know how much our contribution is to that, because I know that there have been periods of greater heat and warmth in the past but I believe we contribute to that. And so I think it's important for us to reduce our emissions of pollutants and greenhouse gases that may well be significant contributors to the climate change and the global warming that you're seeing." Four months later, in October 2011, he said, "My view is that we don't know what's causing climate change on this planet. And the idea of spending trillions and trillions of dollars to try to reduce CO2 emissions is not the right course for us." He expressed his opposition to cap and trade plans and to regulation of carbon emissions. In June 2012, Romney's domestic policy advisor Oren Cass told the "Los Angeles Times", "He's a supporter of renewable energy, as long as it's anything that would be economically competitive. He doesn't know the extent to which climate change is occurring or that human activity is causing it. ... What you won't see are mandates or taxes or regulations that interfere with economic activity."