I’ve just finished Jared Diamond’s big book, Collapse, which is about civilizations and the reasons they fall to pieces and die, along with most of the people in them. Diamond looks at—among others—the Maya, Easter Islanders, Greenland Vikings, the Anasazi, and contemporary Rwandans and Australians and Montanans for examples of humans destabilizing their environments and wrecking their own futures.

The Easter Islanders, for example, landed on a forested paradise that held everything they needed to sustain their culture—rich soil, trees for their ocean-going canoes, fine-grained basalt for their tools. Less than half a millennium later, they were eating rats and each other to keep from starving. Their canoes were made out of reeds and capsized in mild surf far short of their fishing grounds. Their island was an eroded, treeless, stone-strewn outcrop that couldn’t support a social order any discernable distance from savagery.

As he surveys cultures that went belly up, Diamond identifies climate, neighbors, environmental damage, and poor leadership as the things that cause a culture to live or die. And although he claims his book is optimistic, I think that’s just a rhetorical device to get you to buy it. I’m pretty sure that if you take the first letter of each chapter and put them all together, they’ll spell out WE’RE TOAST.

Diamond’s timeline for our own civilization’s downfall is somewhere between 2030 and 2050, which is good news if you’re 55 or above, bad news if you’re younger or if you have children who turn up their noses at rat casserole.

How the collapse of America will come about is not spelled out directly. But you can recognize some of our looming problems in Diamond’s discussion of, say, Australia, with its twenty million people. Twenty million people in an area the size of the lower 48 states doesn’t sound like much, but it is when the continent is a giant salt flat. Diamond says that the sustainable human population of Australia is about eight million, which should give pause to all you people who have decided to move there because George W. Bush got reelected.

Three hundred million people in America sounds like a lot, and it sounds like even more when you realize that we’re paving over or eroding to desert or building subdivisions on our farmland. The reason we can behave in this manner is due to cheap imported agricultural products, cheap imported oil, and cheap imported labor. Make any of those three impossible to get, and we’ll be tearing up tract homes to get at the farmland buried underneath them.

Diamond says that our use of resources in the world, due to the huge human population and our mechanized methods of resource extraction, put us in the position of Easter Islanders. We’re consuming resources faster than they can be replaced, and we can’t get more food or resources off-planet. At present, we can’t even fix the Hubble Telescope, which is about the most convincing demonstration that we’re stuck on-planet that I know of.

We’re also stuck on a planet where economic justice is an impossibility, because if we were to bring all 6.2 billion humans to the standard of living of the average American, the strain on world resources would price some necessities, like Big Macs or gasoline, out of reach of the average American, and the average American won’t stand for that without a fight.