When a large amount of CO 2 is released from a tank due to material or mechanical defects in a CO 2 carrier, both humans and the carrier itself may be in serious danger. The released CO 2 can damage the carrier because CO 2 is released at a low temperature. In addition, the released CO 2 can be hazardous to humans because it may cause an oxygen deficiency over a large area. Thus, if a detection system senses a CO 2 leak from a storage tank, jettisoning and ventilation systems are both activated. The jettisoning system completes the evacuation of liquid CO 2 from the defective tank, and the ventilation system vents the CO 2 gas that has accumulated inside the ship to the outside. The impact of the released CO 2 on humans depends on the stack location and the features of the jettisoning system and the ventilation system. To reduce the hazards associated with CO 2 leaks, the location of the stack should be carefully chosen on the basis of multiple factors, such as the ship speed, the jettisoning rate, and the leakage rate. This study numerically investigates the dispersion of CO 2 released by jettisoning and ventilation with respect to stack location, mass flow rate, and ship speed.