Human metabolic CO₂ output rose an estimated 74% from 1985 to 2015

Researchers estimate that people produced 2.05 billion metric tons of CO₂ through metabolism in 2015, up from 1.18 billion in 1985. Population growth accounted for more than 60% of the increase. This carbon largely comes from plants that recently absorbed it, unlike the long-stored carbon released by burning fossil fuels. Accounting for metabolism could help improve carbon budgets.