It’s hard to imagine a world without chocolate milk, rocky road ice cream or double-fudge sundaes. But if present trends continue, cacao trees (Theobroma cacao) — the source of cocoa and, ultimately, chocolate — could become extinct by midcentury. That’s because cacao and the agricultural system supporting it face both manmade and natural threats that may prove existential.

Consider: Cacao trees grow in a narrow geographic band that, at best, extends 20 degrees north and south of the equator but promises to shrink as climate changes. Fungal diseases have already effectively destroyed the Central American crop, while surviving trees continue to age and lose productivity. And population growth and urbanization eat up ever more land that could otherwise go to new plantings — if only farmers themselves weren’t fleeing agriculture for surer opportunities elsewhere.