Significance Fire is an increasing climate-driven threat to humans. While human demography can strongly modulate fire ignition rates or fire suppression, changes in CO ₂ released by fires feed back to climate. We show that human demography could reduce future fire activity, which would in turn attenuate global warming via an enhanced land carbon sink. This mitigation is strongest in a low–CO ₂ -emission world, corresponding to ∼5 to 10 y of global CO ₂ emissions at today's levels by 2100. We highlight the strong role of human demography in global fire reduction and the potential for climate change mitigation by enhanced land carbon sequestration. We also note possible trade-offs, including loss of biodiversity in fire-dependent ecosystems and increases in severe fire events.