My suggestion is that we should first work to ensure the Third World has clean drinking water and sanitation.

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 total efforts of the last 20 years of climate policy has likely reduced global emissions by less than 1 percent, or about 250 million metric tons of carbon dioxide per year.

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.

My suggestion is that we should first work to ensure the Third World has clean drinking water and sanitation.

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.

Think on a 50-year scale, which is a much more natural time-scale for global warming. The US is right now spending about 200 million dollars annually on research into renewable energy.