How do you capture the realities of climate change in a novel — not just its causes and symptoms, but the ever-changing, ever-weirder ways it is manifesting, within the conventional framework of a story with a beginning, middle and end?

Answering that question is, according to the writer Amitav Ghosh, the literary world’s great challenge. “I feel completely convinced that we have to change our fictional practices in order to deal with the world that we’re in,” he said.

“Something this big and this important, there have to be an infinite number of ways to just talk about it,” he said, similar to how war, slavery, colonization, famine and other crises and events have seeped into so many forms of literature.

Ghosh, 63, is attempting to add something to the conversation with “Gun Island,” his 12th book . The novel, which comes out Tuesday, leaps from the United States, to the Sundarbans mangrove forest between India and Bangladesh, to Italy, places where rising temperatures and water levels have uprooted human and animal lives and upended political systems.