About two years ago, I realised the military in various countries were starting to do climate change scenarios in-house - scenarios that started with the scientific predictions about rising temperatures, falling crop yields, and other physical effects, and examined what that would do to politics and strategy. The scenarios predicted failed states proliferating because governments couldn't feed their people; waves of climate refugees washing up against the borders of more fortunate countries; even wars between countries that shared the same rivers. 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. The first is simply this: the scientists are really scared. Their observations over the past two or three years suggest everything is happening a lot faster than their climate models predicted. The second conclusion is that the generals are right. Food is the key issue, and 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 one degree rise in average global temperature will take a major bite out of food production in almost all the countries closer to the equator than to the poles, and that includes almost all of the planet's bread-baskets.Countries that can no longer feed their people will not be able to buy their way out of trouble by importing grain from elsewhere. 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 staffs 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 and avoid further warming. 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. Most climate scientists think that point lies not far beyond two degrees hotter. 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. So - final conclusion - we will have to cheat. In the past two years, various scientists have suggested several techniques for holding the temperature down directly. We might put a temporary chemical sunscreen in the stratosphere by seeding it with sulphur particles, for example, or we could artificially thicken low-lying 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 are probably going to see the first experiments with these ideas within five years.There is a way through this crisis, but it isn't easy and there is 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, is published in Australia by Scribe.