The climate change problem is at its heart an ethical problem. It's a problem of income distribution and it's a problem of income distribution with dimensions that we don't usually think about very much.

I see myself as a climate change skeptic and a skeptic looks at the evidence and bases conclusions on the evidence rather than on belief. To hold the view that this is not an issue that you need to do something about, to hold the view that it's all a furphy takes belief.

The international equity question arises from the costs of climate change itself and mitigation varying greatly across countries. It is affected by the historical responsibility for current greenhouse gas emissions, which countries which were not responsible for what's in the atmosphere now think are very important. Currently rich countries don't think those issues are very important.

Every climate scientist has his or her own views on some issues that differ from the mainstream in detail. But the broad findings of the IPCC (Intergovernmental Panel on Climate Change) have general support amongst scientists with relevant specialist expertise. The broad wisdom of the IPCC is strongly contested by a small number, and a small minority, of reputed climate scientists. It is not contested by the large majority of specialists, and by the leaders of the relevant learned academies in the countries of great scientific accomplishment.

A revolution in humanity's use of fossil fuel-based energy would be necessary sooner or later to sustain and to extend modern standards of living. It will be required sooner if we are to hold the risks of climate change to acceptable levels. The costs that we bear in making an early adjustment will bring forward, and reduce for future times, the costs of the inevitable eventual adjustment away from fossil fuels.

It crosses my mind that our generation may leave problems that are simply too hard for human society in the generations that follow. The structures that separate civilisation from disorder are thin and fragile. (But) I am not gloomy by nature so don't presume that the global community will fail the young people.

Economic development over the past two centuries has taken most of humanity from lives that were brutal, ignorant and short, to personal health and security, material comfort and knowledge that were unknown to the elites of the wealthiest and most powerful societies in earlier times.