Jenny Offill’s feted 2014 novel “Dept. of Speculation” had the feel of a finely calibrated stand-up routine, snippets of storytelling embedded with jokes and propelled along by a poignant sense of inevitability. It was a virtuoso performance, and Offill’s new novel, “Weather,” unfolds in a similar way — impressionistic, jokey, vaguely chronological. But where “Dept. of Speculation” looked inward, at the depths of marriage and motherhood, the concerns of “Weather” are existential.

Like a sort of literary shadow box, the novel collects images and instances from the past few years, with the 2016 election as a clarifying point in this picture of a fraught and fragmenting world. Again, there are jokes, factoids and quotes, as well as a healthy dose of survivalist lore, as the narrator, Lizzie, contemplates a “doomstead” — in light of dire climate data and roiling political and social currents.

Lizzie, of course, is not really serious about this, but it is one of the wonders of Offill’s writing that her light touch lets us glimpse the very real dread lurking underneath. Lizzie is a university librarian, and her work exposes her to all kinds of characters — the curious, the crazy, the sad and the sober — whose questions she absorbs and sometimes tries to answer.

She also answers e-mail sent to her onetime professor and mentor, Sylvia, whose podcast, “Hell and High Water,” attracts “lots of questions about the Rapture mixed in with the ones about wind turbines and carbon taxes.” For instance: Why do humans like applause? Who invented contrails? How did we end up here?

Also: “How do you maintain your optimism?” Not very well, one suspects, when she tells Lizzie, “I’m about to send off this article, but I have to come up with the obligatory note of hope.” And yet this is the question that resonates through “Weather,” as Lizzie navigates tricky relationships with her husband, a classics Ph.D. who makes educational video games; her son, an amusing and soulfully quirky little boy; her brother, a recovering addict with a tenuous grasp on “normal” life; and the neighbors, merchants, patrons and odd others who people her days.

To the extent that this story moves, in any conventional sense, Lizzie’s beloved, troubled brother Henry is the catalyst. “Stick together, you two. That’s what my mother used to say,” she tells us. To do so means holding off the darkness that perpetually threatens to engulf him — a feat that in turn threatens Lizzie’s other obligations.

Thus Henry, in his fragile state, makes all the more abstract existential fears that course through “Weather” intimate, immediate and sharply, sometimes comically, real. If he — and Lizzie, and, yes, this book — manage to hold together in good humor amid all the madness, detritus and peril collected here, there may be good reason to maintain one’s optimism. The note of hope, obligatory though it may be, comes through.

Ellen Akins is a writer and teacher of writing in Wisconsin.

Weather
By: Jenny Offill.
Publisher: Alfred A. Knopf, 207 pages, $23.95.