I really try to say things as they basically are and it so happens that it is a good message that things are getting better, but there are still problems.

It seems incontrovertible to me that there is a global warming effect and that it is going to be serious, probably not in the amount of, say, six degrees warming, but it's likely that we'll get two to three degrees warming and that will be serious enough.

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.

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.

Money spent on carbon cuts is money we can't use for effective investments in food aid, micronutrients, HIV/AIDS prevention, health and education infrastructure, and clean water and sanitation.

We need to invest dramatically in green energy, making solar panels so cheap that everybody wants them. Nobody wanted to buy a computer in 1950, but once they got cheap, everyone bought them.

When thinking about the future, it is fashionable to be pessimistic. Yet the evidence unequivocally belies such pessimism. Over the past centuries, humanity's lot has improved dramatically - in the developed world, where it is rather obvious, but also in the developing world, where life expectancy has more than doubled in the past 100 years.