“American War” is one of several new dystopian novels that seem to channel the country’s current anxieties, with cataclysmic story lines about global warming, economic inequality, political polarization and the end of democracy. If there’s a thematic thread connecting this crop of doomsday books, it could be crudely summarized as, “Things may seem bad, but they might become much, much worse.”

In Lidia Yuknavitch’s novel “The Book of Joan,” the planet in 2049 has been destroyed by war and climate change, and the wealthy have retreated skyward to a ramshackle suborbital complex controlled by a celebrity-billionaire-turned-dictator who continues to suck resources from Earth. “I built a world that is only a small distance from our present tense,” Ms. Yuknavitch said in an email. “One in which our current aims have simply played out to their logical conclusions: endless war, environmental degradation, the exploitation of Earth as a resource, the brutal stratification of humanity.”

Similar catastrophic events propel Zachary Mason’s “Void Star,” a mind-bending novel in which rising seas have rendered large swaths of the planet uninhabitable, and impoverished masses huddle in favelas in San Francisco and Los Angeles, while the rich have private armies and armored self-driving cars and undergo life-extending medical treatments. Mr. Mason, a computer scientist who specializes in artificial intelligence, envisioned a world where the boundaries between machines and people have grown increasingly porous, and a powerful, godlike A.I. hacks into people’s minds.

The future is even bleaker in Michael Tolkin’s “NK3,” which takes place in Los Angeles, after a weaponized microbe developed by North Korean scientists has swept the globe, destroying people’s memories and identities. The writer Chris Kraus called the novel “brilliant and barely speculative” and labeled it “the first book of the Trump era.”

(For readers longing for a sliver of utopia, slightly less alarming visions of the future can be found in Kim Stanley Robinson’s “New York 2140,” in which the city is partly submerged by rising oceans but remains vibrant; and Cory Doctorow’s darkly funny “Walkaway,” a forthcoming novel about an idealistic man’s search for purpose in a country that has been leveled by extreme weather, economic disparity and the collapse of civil society.)