Contribution
The utility of partial contrail avoidance
Gierens, Klaus
Meteorologische Zeitschrift (2025)
publication en ligne: Jul 24, 2025
manuscrit accepté: Jun 19, 2025
revision du manuscrit reçu: Jun 13, 2025
révision du manuscrit demandée: Jun 4, 2025
manuscrit reçu: Mar 17, 2025
DOI: 10.1127/metz/1275
Open Access (article peut être télechargé gratuitement)
Abstract
A simple theory is developed to measure the utility of the avoidance of single contrails out of a larger ensemble of contrails. The utility is defined here as the mitigated contrail climate effect resulting from contrail avoidance. Side effects of increasing fuel consumption and corresponding emissions are considered in the form of a separate cost function. The model is simple and its results are qualitative only. This is sufficient for the desired insight into and illustration of the principles. A quantitative treatment would need the application of a detailed numerical model that takes the complete air traffic in a certain region and time into account; this is beyond the current purpose. The utility function is expressed as a function of the fraction of the avoided contrails in a given area at a certain time relative to all contrails present. It is a more or less non-linearly increasing function. The non-linearity is weak if the total contrail cover is low, but there is strong non-linearity in cases with high contrail coverage. In a given synoptic situation, the maximum achievable utility increases with total contrail coverage: low/high contrail coverage implies small/large achievable utility (climate benefit). The strong non-linearity in the high coverage case implies that most of the contrails must be avoided to achieve high utility. If only single or a few contrails are avoided in such a situation, the utility is low and it may well be smaller than the corresponding climate cost. The main result is that in order to estimate the climate benefit of avoiding single contrails it is necessary to consider the whole traffic situation with all other contrail-producing aircraft. Otherwise, gross errors result. For eco-efficient contrail-avoiding strategic flight-planning it is required as well to consider in advance all the other flights in the same region that might produce contrails.
Mots-clefs
contrails • contrail avoidance • utility function • climate benefit