Is it in the UK's interests to leave the EU? It depends on your values. The answer can't be read off of GDP statistics under various scenarios or some measures of global influence.

I see a lot of individual action when it comes to environmental questions really as a form of politics as a way of communicating with political leaders, much in the same way that acts of civil disobedience during the civil rights' movement were really acts of political communication, trying to get laws changed rather than based on the thought that the individual action would really change the practices of segregation.

When I first started studying climate change back in the 1980s, I was struck by how difficult it was be for people to understand this issue.

Obama's clean power plan, methane regulations, and increased fuel economy standards are about as good as our political system can do at this point in our history. Let's embrace these things, make them work, and push for more, rather than denouncing them because they're 9th best (which they are).

The Enlightenment dream is a good one. The idea that people should rationally appreciate their place in nature, assess threats and possibilities, and regulate their behavior in response is inspiring.

None of us are rational economic men as we're supposed to be portrayed in economic theory where mixes of passions, of desires, of moral principles, of self-deception, of altruism, of concern of others, of concerns for ourselves and an interest in our bank accounts. And social policies have to be responsive to the complexity of who we are as people or else, like the war on drugs, they're simply going to fail.

I think when it comes to climate change, the single most important thing in the world is for the United States' Congress to pass an effective bill that will put a price in carbon because if it starts costing something to emit carbon, this will provide an incentive, people do act on the basis to some extent of economic incentives to emit fewer greenhouse gases.