 Climate change denial in the United States is almost entirely motivated by politics. A lot of scientists have thought that it was a problem of science illiteracy, that it was a problem of public understanding, that if we just explained the science better that then we would solve this problem. And that doesn't work because the problem is not being driven by lack of access to information, although that may play a role in some cases. The problem is being driven by people not wanting to believe the science because they don't like its implications. When it comes to the drivers of belief or acceptance of scientific findings, in particular climate change, then what we find is that one of the most important factors is a person's worldview, or you can call it a political ideology, their belief in things such as the free market. And it turns out that in particular, in the case of climate change, that people who are very enthusiastic about free markets and who think that government should not interfere with free markets, that they tend to reject the findings from climate change, climate science, based on that ideology. And it's a very strong effect. It's a huge effect. If you take climate science seriously, it means we need to do something. We need to do something that changes the way we operate. And that something could be very personal, could be changing the way you live, could be becoming a vegetarian or not traveling or building a zero energy home. But it also could be something that the government does. And a lot of the early attention about climate change particularly focused on governance. They focused on either the idea of international governance in the form of, say the UN Framework Convention on Climate Change, or focused on national governance in the form of a carbon tax or an emission trading system. So these are government interventions in the marketplace. In the case of climate change, where it's more of a political ideology and or an economic ideology, the concerns are more along the lines of, well, if climate change is true, that means that we're going to have to strengthen central government because we're going to have to take steps to curb the carbon production so that we can reduce the amount of CO2 in the air. That means a bigger central government. As political conservatives, we don't want a big central government. It means we're going to have to put some constraints on capitalism, that socialism. So there's a lot of things that political conservatives are going to lose also if climate change is right. So if you don't like the idea of a government intervention in the marketplace because you believe in free market economics, or you just worry about government encroachment, you worry about expanding government, then the kinds of solutions that are being put forward for climate change are things you don't like. And so that's a major, probably the single major reason why the Americans who reject climate science do it. Because if you look at the data on it, what you see is that the strongest correlation between climate change denial is with a certain kind of conservative politics that emphasizes the free market. It's not correlated with race, it's not correlated with age or gender or even religious belief with one exception that's tied to conservative politics, right, which is a certain sector of the evangelical community, but it's tied to a set of conservative beliefs about governance. The main reason why people don't think climate change is real is not because of lack of facts. Most of the people that I meet from day to day, the lady in the grocery store or the man across the street, they have arguments at the tip of their fingers as to why they don't think climate change is real. They will cite the stolen emails, they will say, oh, global warming stopped 17 years ago. They have arguments, factual or semi-factual based arguments about why it's not true. So why is everybody so convinced? It's because we are all cognitive misers. We don't have the brain power to understand every single issue in the world. I don't know if we ever did, but especially now, I mean, I don't understand the fundamentals of stem cell research. I don't really understand the pluses and negatives of nuclear power to be perfectly honest. I certainly don't understand the economic benefits and trade-offs of all the various climate policies that are being considered. And so you can understand how the average person doesn't understand the climate science. So what do we do? We go to people we trust. And in the United States, when we look at people we trust, if you look at the conservative half of the country, with one voice, conservative media, conservative thought leaders and conservative politicians are telling us that this isn't a real problem. In the literature, there are some accounts that I consider to be top-down in explaining opposition to things like clean air and clean water. That is, there are political elites. There are ideological think tanks. There are large donors. There are media networks that are arguing from the top and telling people that these are the arguments, these are the positions. Here are some scientific sounding rationale or an economic sounding rationale. That all being top-down. Then bottom up, I think there are people who are more or less inclined to listen to those arguments and to credit them or to discredit the alternatives. And some of that may be psychological. Some of it may have to do with your social position. We see all kinds of differences in terms of gender and education and age, but dominated by differences in ideology, worldview, or political party. It's frustrating, right? Because there shouldn't be a serious role for politics in climate science in my opinion. The science is science. And it was, right? The first time I ever testified to a subcommittee of the U.S. Senate was 12 years ago. And it was chaired by a Republican who was about to introduce a bill that was going to put a price on changing the climate through carbon emissions. And I personally think that he was just a little bit unhappy with me because I was not scarier about the threats. I was being very careful and measured. And this is that long ago. And so the idea that somehow your politics that you're on this side or that side means that you do or don't believe that CO2 is a greenhouse gas, there is a little bit of that now, but it's a very, very recent thing. And it's the thing that I think that I hope can disappear again. You have to explain to the majority of people why there is a small but vocal minority that is denying the science. So I think it's very important for the public to understand that those people are motivated by factors such as personal ideology. I mean, if I have one message, that's what my message has been all long. And it still is, this is not a scientific debate. It's a political debate. But it's a political debate being made to look like a scientific debate.