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.

The military profession, especially in the long-established great powers, is deeply pessimistic about the likelihood that people and countries will behave well under stress. Professional officers are trained to think in terms of emergent threats, and this [climate change] is as big a threat as you are going to find. Never mind what the pundits are telling the public about the perils of climate change; what are the military strategists telling their governments? That will tell us a great deal about the probable shape of the future, although it may not tell us anything that we want to hear.

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.

For most of history, war has been a more or less functional institution, providing benefits for those societies that were good at it, although the cost in money, in lives, and in suffering was always significant. Only in the past century have large numbers of people begun to question the basic assumption of civilized societies that war is inevitable and often useful.

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.

But we are almost certainly going to miss our [global warming] deadline. We cannot get the 10 lost years back, and by the time a new global agreement to replace the Kyoto accord is negotiated and put into effect, there will probably not be enough time left to stop the warming short of the point where we must not go.

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.