Henri Cornec, Zachary Wendling , Marc Shapiro, T. Reed Miller

The aviation sector faces a significant challenge in mitigating climate change due to the dual impact of CO2 emissions and contrail formation. Contrails, which form under specific atmospheric conditions, contribute to global warming. Mitigating contrails, however, can require flight path diversions, leading to increased fuel consumption and CO2 emissions. This study evaluates various climate equivalence metrics that can be used to quantify these impacts in common units. The analysis involves a comprehensive survey of existing metrics, criteria for their selection, and a framework for decision-making regarding contrail avoidance. Using a representative flight as an illustration, the research highlights the implications of different metrics on the decision to divert flights to minimize climate impact. The study emphasizes the importance of integrating both short-term and long-term climate impacts in aviation policy and provides a decision matrix to guide airline operators. This work is crucial for developing effective mitigation strategies that align with global climate goals, considering the rapid growth of air traffic and its substantial contribution to radiative forcing. The findings support the adoption of informed, metric-based guidelines for contrail avoidance, ensuring sustainable aviation practices.