I realized two years ago that the military in various countries were starting to run climate change scenarios in-?house. So I started interviewing everybody I could get access to: not only senior military people, but scientists, diplomats and politicians. About 70 interviews, a dozen countries and 18 months later, I have reached four conclusions that I didn't even suspect when I began.
The first is simply this: the scientists are really scared. Their observations over the past two or three years suggest that everything is happening a lot faster than their climate models predicted. This creates a dilemma for them because they have been struggling against a well-?funded campaign to cast doubt on the phenomenon of climate change.
Now that people and even governments are finally listening, the scientists are understandably reluctant to announce publicly that their predictions were wrong; the situation is really much worse, and the targets will have to be revised.
So governments, at last awakened to the danger, are working to the wrong emissions targets. The real requirement, if we are to avoid runaway global warming, is probably 80 per cent cuts by 2030 and almost no burning whatever of fossil fuels (coal, gas and oil) by 2050.
The second conclusion is that the generals are right. Food is the key issue, and the world food supply is already very tight. We have eaten up about two-?thirds of the world grain reserve in the past five years, leaving only 50 days' worth in store.
Even a 1°C (1.8°F) rise in average global temperature will take a major bite out of food production in almost all the countries that are closer to the equator than to the poles, and that includes almost all of the planet's breadbaskets.
Countries that can no longer feed their people will not be able to buy their way out of trouble by importing grain from elsewhere, even if they have the money.
Starving refugees will flood across borders, whole nations will collapse into anarchy - and some countries may make a grab for their neighbours' land or water. These are scenarios that the Pentagon and other military planning staff are examining now. They could start to come true as little as 15 or 20 years down the road. If this kind of breakdown becomes widespread, there will be little chance of making or keeping global agreements to curb greenhouse gas emissions.
The third conclusion is that there is a point of no return after which warming becomes unstoppable - and we are probably going to sail right through it.
It's 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°C hotter (3.6°F). Once that point is passed, the human race loses control: cutting our own emissions may not stop the warming. But we are almost certainly going to miss our 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.
So - final conclusion - we will have to cheat. In the past two years, various scientists have suggested several "geo-?engineering" techniques for holding the temperature down directly. We might put a kind of temporary chemical sunscreen in the stratosphere by seeding it with sulphur particles, for example, or we could artificially thicken low-?lying maritime clouds to reflect more sunlight.
These are not permanent solutions, merely ways of winning more time. But the situation is getting very grave, and we're probably going to see the first experiments with these techniques within five years.
There is a way through this crisis, but it isn't easy and there's no guarantee of success. As the Irishman said to the lost traveller, "If that's where you want to go, sir, I wouldn't start from here."
Gwynne Dyer's new book, Climate Wars, has just been published in Canada by Random House.