 Psychology doesn't seem like it would have much to do with climate change, but actually it's important because each of us, the 7.5 billion people on the planet, are where the climate relevant things begin. It's what we do every day that makes a big difference. The most important factors are to first to identify what are the obstacles that people face, what are the barriers that they face. Almost everybody's in favor of the environment, but not all of us are doing everything that we can. So it's important to diagnose, almost like a physician would diagnose the problem and figure out what are the barriers and obstacles that people face so that they're able to overcome them and do the right thing with the environment. Many challenges that policymakers face, but perhaps the most important ones are to find ways to help people overcome the barriers in a way that doesn't require a lot of sacrifice or a lot of going against people's values, to find ways that are compatible with people's lifestyles.