Contrail Climate Forcing Disclosure Register

PROBLEM: Lee et al. 2021 decomposed aviation's climate impact and found contrail cirrus is the largest single piece: 57.4 mW/m² of effective radiative forcing in 2018, about 57% of aviation's net total, against 34.3 mW/m² for all aviation CO₂. Yet contrail forcing is disclosed nowhere in airline reporting — passengers, investors and regulators see the CO₂ number and never the larger contrail number.

SOLUTION: A contrail climate forcing disclosure register: every operator's contrail forcing estimate logged per route and per year, next to its CO₂ figure, with the uncertainty range shown — so the largest aviation climate impact is disclosed, not hidden behind the smaller one.

EVIDENCE BASIS: DOCUMENTED — Lee et al. 2021, Atmospheric Environment 244, 117834: net aviation ERF 100.9 mW/m² (2018); contrail cirrus 57.4 (17–98); CO₂ 34.3 (28–40); aviation ~3.5% of anthropogenic ERF. Sources: Lee et al. 2021, doi:10.1016/j.atmosenv.2020.117834.