Human Metabolism Emits 2 Billion Metric Tons of CO₂ Annually, University of Bath Study Finds

A new study led by the University of Bath reveals that human metabolism alone generates an estimated 2.05 billion metric tons of carbon dioxide each year, a 74% increase since 1985. The research quantifies how the simple act of breathing out CO₂—a byproduct of converting food into energy—contributes to global carbon flows. While this figure is dwarfed by fossil fuel emissions, it highlights an often-overlooked biological component of the carbon cycle. The findings may help scientists refine models of carbon sources and sinks, especially as the global population grows and dietary patterns shift. Understanding this baseline human emission could improve climate projections and inform sustainability strategies. Ultimately, the study underscores that even our most basic biological functions are part of the planet’s carbon equation.