I think a few hundred years from now we'll start having the 'posthuman' era of different species.

We need to broaden our sympathies both in space and time - and perceive ourselves as part of a long heritage, and stewards for an immense future.

The politics is far harder than the science. And even if we accept the science we have a big issue of how to deal with it.

If we ever establish contact with intelligent aliens living on a planet around a distant star ... They would be made of similar atoms to us. They could trace their origins back to the big bang 13.7 billion years ago, and they would share with us the universe's future. However, the surest common culture would be mathematics.

I'm not a specialist in the science but I have followed it fairly closely and it seems to me that there is among the experts a clear consensus that potential climate change is something to worry about.

In this century, not only has science changed the world faster than ever, but in new and different ways. Targeted drugs, genetic modification, artificial intelligence, perhaps even implants into our brains - may change human beings themselves.

The important point there is that when people talk about a mean temperature rise of say two, three or four degrees that's a sort of global average which really is a signature of large scale change in climatic patterns.