Contrails and negative externalities

Contrails, or condensation trails, are thin streaks of cloud created by aircraft exhaust fumes that contribute to global warming by trapping heat in the atmosphere. While the exact warming effect of contrails is uncertain, scientists believe it is greater than warming caused by carbon emissions from jet fuel. See image below.

Aircraft cause warming in two ways: greenhouse gas emissions and contrails. That’s because contrails (aircraft condensation trails) often grow into cirrus clouds that trap heat in the lower atmosphere and significantly add to global warming. Recent estimates show that contrails cause about the same amount of warming each year as all the CO2 emitted by all flights from 1945 to 2018. See below for airline commitment to contrails.

This warming effect is considered a negative externality of production because it’s a cost imposed on society by the aviation industry without being directly reflected in the cost of air travel see graph. MSC reflects both the private cost (MPC) of the airline and the external cost (contrails) that it doesn’t pay for.

Below are the three primary areas for reducing contrails:

• Cleaner Fuels – sustainable Aviation Fuel (SAF): Blends with fewer aromatics reduce soot emissions by 50-70%, impacting contrail formation.

• Engine Modifications – use advanced engine technology to reduce soot emissions and weaken contrail formation.

• Smarter Flight Routing – avoid flight paths through ice-supersaturated regions (ISSRs) where contrails form.

For more on externalities view the key notes (accompanied by fully coloured diagrams/models) on elearneconomics that will assist students to understand concepts and terms for external examinations, assignments or topic tests.