What they are and where they fall is still very much debatable.
Sir Nicolas Stern was commissioned recently by the Labour government to produce a report on the economics of climate change.
George Monbiot, who writes for the Guardian newspaper, says about this report,
He [Stern] showed that stopping runaway climate change would cost less than failing to prevent it. But because his report was so long, few people bothered to find out how he had achieved this result. It took me a while, but by the time I reached the end I was horrified.
He cites the UK government’s proposal to build a third runway at London’s Heathrow airport. Its consultation paper states that their approach was entirely consistent with the Stern review. Monbiot summarises,
Its central case is that the economic benefits of building a third runway outweigh the economic costs. The extra capacity, the government says, will deliver a net benefit to the UK economy of £5bn. The climate change the runway will cause costs £4.8bn.
His point is that convenience is weighed against human life,
The people most likely to be killed by climate change do not live in this country. Most of them live in Africa and south Asia. Hardly any of the economic benefits of expanding Heathrow accrue to them. Yet the government has calculated the economic benefits to Britain, weighed them against the global costs of climate change and discovered that sacrificing foreigners - especially poor ones - is a sensible economic decision.
It seems that nowadays any economic progress in one part of the world is equivalent to creating a problem for humanity in another part. It’s an equation we are going to have to face more and more.