Zonked on patriotic zeal, Americans believe that their country is an exception to all historical rules. The land of the free, however, is currently hurtling towards a predetermined, apparently unavoidable crack-up. Its governmental institutions are paralysed, and a constitution devised for an agrarian society in the 18th century obstructs reform; its citizens, outnumbered by the guns they tote, have split into armed, antagonistic tribes. Given these conditions, the riot at the Capitol last January may have been the rehearsal for an imminent civil war.

Looking down at this hot mess from chilly Toronto, the Canadian novelist and essayist Stephen Marche grimly predicts: “The United States is coming to an end.” Such a declaration could only be made by an outsider. To Americans, the idea of civil war remains unthinkable, the words unspeakable: at his inauguration Biden vowed to end “this uncivil war”, which implied that the only missiles being exchanged were harmlessly verbal. As Marche sees it, the impending war will be a continuation of the earlier one between Union and Confederacy, which broke off in 1865 without closing the gap between races, regions and economic prospects. To these human-made iniquities Marche adds the intemperance of nature: New York is likely to be inundated by a forthcoming hurricane, and Californian forests are already burning. In 1776 the founding fathers envisaged an egalitarian renewal of humanity. Now the decline of the US warns that the anthropocene era may be doomed. Marche, doubting that the walls erected by Fortress America can keep out refugees, the poor and the rising oceans, suspects that this is “how a species goes extinct”.

The Next Civil War is fatalistic yet somehow elated as Marche vividly imagines the “incredibly intense events” that lie ahead. He has done the required historical research and conducted interviews with officials and academic experts, but he can’t resist elaborating scenarios for conflagration and collapse which he offers as examples of “the genre of future civil war fantasy”. One of these, narrated with sour amusement, concerns an explosive dispute in a western state where local protesters, riled up by a wily, cynical sheriff, do battle with federal bureaucrats who have closed down an unsafe bridge. Another, which resembles the plot of the disaster movie The Day After Tomorrow, follows an evacuee from flooded Brooklyn who pauses to reflect that a sunken highway looks “almost beautiful”. A third “thought experiment” tracks a nerdy loner who guns down the US president in a Jamba Juice outlet, after which a commentator solemnly describes the motive of misfits like this as a “desire for transcendence”.

As Marche says, “the power of spectacle is driving American politics”, and his “cultural scripts” turn terror into lurid entertainment. He takes his cue from movies such as Independence Day or Olympus Has Fallen, which stage the apocalypse as an adventure ride; the difference is that this time no superhero flies or rides in to rescue the republic. Marche awards “iconic status” to the atrocities of 9/11 but mocks the agitators in his own fable about the bridge as “ludicrous fanatics” who seem to be dressed for Halloween or a rock festival: is he daring them to do better? There is a tempting, titillating danger to this, because sooner or later such prophecies will be fulfilled in action. Marche may be enjoying his novelistic nightmares a little too much, possibly even smirking from the safety of Canada as the US dismembers itself.

A similarly excited anticipation of the end briefly disrupts Barbara Walter’s study, How Civil Wars Start and How to Stop Them. Walter teaches political science in San Diego, and she writes with dutiful academic sobriety as she compares her disintegrating country to failing states in the Balkans and the Middle East. She studies graphs, fiddles with data sets and deploys nonsensical jargon, classifying the US as an “anocracy” because it is midway between democracy and autocracy. But her droning lecture flares into life when she, like Marche, sets herself to imagine what an American civil war would look like. Projected ahead to 2028, the result resembles a hyped-up Hollywood pitch, with the synchronised detonation of dirty bombs in state legislatures, a botched presidential assassination bid, freelance militias patrolling the streets, and – worst of all! – assaults on big-box stores. Like Marche, Walter is aware that political warriors need the support of a “mythic narrative”, and she notices that some of the insurrectionists at the Capitol carried Bibles: in the absence of a sacred text, will the garbled synopsis of a disaster movie do just as well? After these dramatic flurries, Walter calms down as she suggests ways of averting conflict. Most of her proposals require constitutional change, which she must know will never happen or will come too late; she also recommends reintroducing the study of civics in American schools, as if those pious courses in communal engagement could be an antidote to civil war.

Walter admits that following the last election, when Trump refused to concede defeat, she and her husband considered emigrating. They flicked through their flotilla of available passports – Swiss, German and Hungarian as well as American and Canadian – and decided on driving north to cross the border into British Columbia. Ultimately they chose to remain in California, as Walter announces after ritually reciting the national creed and thanking the US for “the gift to pursue our dreams”. Marche concludes his book with a more guarded tribute to the perhaps naive American “faith in human nature” and the constitution’s risky “openness to difference”. He then explains why he is glad to live in Toronto: Canadians, he says, “talk placidly and exchange endless nothings” rather than bragging, ranting and abusing each other like their southern neighbours, and they only have the weather’s “cold snaps” to contend with, not incendiary social convulsions. In times such as ours, to be snugly domiciled in a boring country is surely the best bet.

The Next Civil War: Dispatches from the American Future by Stephen Marche is published by Simon & Schuster (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply