On the most primitive, irrational level, no one really believes in endings. It is hard enough to accept, rather than just theoretically understand, that one’s own life is going to end; how much more so when it comes to the way of life of everyone around us, or of human life altogether. And for most of human history, the idea that civilization or the human race might end was indeed fantastic, a matter of religious eschatology, not secular possibility. Nations and empires might fall, and inspire a certain Romantic morbidity – as in Byron’s “Childe Harold’s Pilgrimage,” or Shelley’s “Ozymandias” – but something new would rise to take their place. Only in the 20th century, for the first time, did the possibility of a universal ending become undeniable. From H.G. Wells’s “The Time Machine” to last year’s apocalyptic movie “The Day After Tomorrow,” one of the hallmarks of the modern imagination has been its horrified fascination with the end: the human race vanished or horribly devolved, our skyscrapers more incomprehensible than the pyramids.

“Collapse” (Viking, 575 pages, $29.95), the new book by Jared Diamond – author of the Pulitzer Prizewinning “Guns, Germs, and Steel” – is a prime document of this shift in our imagination of disaster. When the British Empire looked to the past for warnings, it reflected on the decline and fall of the Roman Empire, or feared the day that – in Kipling’s words – Britain would be “one with Nineveh and Tyre.” Yet these were all proud parallels, allowing the modern empire to inherit the glory of the past, even if one day she too would have to hand it on. Mr. Diamond, on the other hand, offers America and the world shaming, terrifying examples: not world-spanning empires but tiny, marginal societies, which did not majestically fall but suddenly fell apart. He points to Easter Island, bristling with idols but stripped of trees and people; to the Maya, discovered by Columbus dwelling in the ruins of a great culture; to the Anasazi, who vanished entirely from the Southwestern United States, leaving behind only their terraced houses and canals.

Mr. Diamond’s book is not just a historical study, but an urgent polemic. What undid all of these civilizations – and others, including the Greenland Norse and the Henderson and Pitcairn islanders – was environmental degradation and its effects on economics and politics. And it is this threat that links our hugely more powerful and sophisticated society with those ephemeral cultures. Moving from the past examples that form the core of his book, Mr. Diamond examines present-day societies – from Montana and Australia to China and Rwanda – where he sees similar catastrophes in the making. “The problems of the ancient Maya, Anasazi, and Easter Islanders,” he writes in his conclusion, “[are] playing out in the modern world. Today, just as in the past, countries that are environmentally stressed, overpopulated, or both become at risk of getting politically stressed, and of their governments collapsing.”

This dual focus on past and possible future collapses results in a virtuously unwieldy book. Mr. Diamond, a biologist and physiologist at UCLA, has amassed a great deal of data about all of his subjects – from the way Easter Islanders transported their statues to land-inheritance struggles in 1990s Rwanda. He adds his personal observations, made on business and leisure trips around the world, of conditions in Montana’s Bitterroot Valley, or at a Chevron oil field in New Guinea. Individually, each of these facts and stories is interesting; taken all together, they can become numbing, and produce a book rather less engaging than it is important.

“Collapse” is, in fact, best understood as several books in one: a historical study of past failed societies, a survey of contemporary environmental crises, and a theoretical argument about how institutions solve, or fail to solve, crucial long-term problems. Of these, the first is the most novel and compelling. Reading Mr. Diamond’s synthesis of the latest research on Easter Island or the Anasazi produces an oddly paradoxical effect: one is simultaneously depressed by the ignorance and waste that ruined these cultures, and awed by the ingenuity that historians and scientists have employed to understand them. Of the five collapsed societies studied by Mr. Diamond, three were preliterate, and only one – the Greenland Norse – was Western. But thanks to modern techniques that Mr. Diamond delightedly explains – soil and sediment analysis, pollen studies, tree-ring and radiocarbon dating – these vanished, deeply foreign peoples can be made to speak.

What they have to say is a more contentious issue. Mr. Diamond acknowledges, but does not adequately address, the obvious doubt that will arise in any reader: Do these past collapses offer genuine analogies for our present plight? The smallest of Mr. Diamond’s examples, Pitcairn and Henderson islands, counted a few hundred inhabitants; the largest, the Maya, had several million people in an area about the size of Colorado. None came close to the size, scale, and complexity of the modern United States, much less the modern world as a whole, which is the real focus of Mr. Diamond’s concern. Why should we seek our resemblance in these particular societies, rather than in other, larger polities – China, for instance – which have survived, though greatly transformed, for many thousands of years?

In response, Mr. Diamond offers less an argument than a metaphor. “The whole world today,” he writes, “is a self-contained and isolated unit. … there is no other island/other planet to which we can turn for help, or to which we can export our problems. Instead, we need to learn … to live within our means.” This is the beginning, not the end, of the argument: Exactly what our means are, how much we have to sacrifice to live within them, and how much time we have to decide, continue to be matters of heated political and scientific debate. But “Collapse” will leave any reader with a sobering sense of the planet’s fragility, and of humanity’s inveterate potential for recklessness.