CO2 stunning is the dominant pig slaughter method globally but causes significant aversion and suffering. Evidence-based reform toward more humane alternatives is gaining traction.
CO2 stunning causes a prolonged period of severe respiratory distress before loss of consciousness. The welfare cost falls on billions of pigs annually. The evidence for better alternatives is clear. However, the capital investment in existing CO2 tunnel systems creates industry resistance to change. Consumer, retailer, and regulatory pressure are the most effective levers for accelerating the transition to more humane stunning.