The second thing is, if you want to do something about global warming, you have to think much more long-term. There is something wrong with saying we should start using renewables now, while they are still incredibly expensive.

The only thing that will really change global warming in the long run is if we radically increase the speed with which we get alternative technologies to deal with climate change.

The fact that we're catching more fish per person than we've ever done before doesn't mean that there are not particular places where we've managed fisheries badly.

If every country committed to spending 0.05 per cent of GDP on researching non-carbon-emitting energy technologies, that would cost $25 billion a year, and it would do a lot more than massive carbon cuts to fight warming and save lives.

I found university a little dispiriting. I thought I would enter the great halls of Plato, but instead I entered the halls of an intellectual sausage factory. I wanted to do something not on the main course, and chose the environment.

Listen, global warming is a real problem, but it's not the end of the world. A 30-centimetre sea level rise is just not going to bring the world to a standstill, just like it didn't over the last 150 years.

In the rich world, the environmental situation has improved dramatically. In the United States, the most important environmental indicator, particulate air pollution, has been cut by more than half since 1955, rivers and coastal waters have dramatically improved, and forests are increasing.