Now, for the moment, we are safe. The only kind of international violence that worries most people in the developed countries is terrorism: from imminent heart attack to a bad case of hangnail in fifteen years flat. We are very lucky people--but we need to use the time we have been granted wisely, because total war is only sleeping. All the major states are still organized for war, and all that is needed for the world to slide back into a nuclear confrontation is a twist of the kaleidoscope that shifts international relations into a new pattern of rival alliances.

The first and most important impact of climate change on human civilisation will be an acute and permanent crisis of food supply. Eating regularly is a non-negotiable activity and countries that cannot feed their people are unlikely to be reasonable about it.

The real requirement, if we are to avoid runaway global warming, is probably 80% by 2030, and almost no burning whatever of fossil fuels (coal, gas and oil) by 2050.

Fiat justitia, ruat coelum. (Do the right thing even if the heavens fall.) It's not nearly as naïve a maxim as it seems, because in the real world it often turns out that doing what is morally the right thing is also, in practical terms, the right thing to do.

While the high-level climate talks pursue their stately progress towards some ill-defined destination, down in the trenches there is an undercurrent of suppressed panic in the conversations. The tipping points seem to be racing towards us a lot faster than people thought.

It doesn't matter what we think we are there [in Afghanistan] for; it matters what they think. They think we are invaders.

There is a point of no return after which warming becomes unstoppable - and we are probably going to sail right through it. It is the point at which anthropogenic (human-caused) warming triggers huge releases of carbon dioxide from warming oceans, or similar releases of both carbon dioxide and methane from melting permafrost, or both. Most climate scientists think that point lies not far beyond 2 degrees C hotter (3.6 degrees F).