Ban very short flights, the tree that hides the forest

Air transport is one of those activities incapable of reducing their impact on the climate. The progress in energy consumption is more than offset by the rapid increase in air traffic and no technological breakthrough is in sight, whatever the sector lobbies say, reduced to promises for the 2040 or 2050 horizon. However, part of civil society and environmental activists are urging the public authorities to act. Of course, no public authority would dare to regulate the volume of air supply to a level that would be tolerable for the climate, which would pose delicate social and economic challenges and would contravene the dogma of the free market.

From then on, all that remains is to target what seems the most extravagant to many observers, whether they are activists or experts: the so-called ultra-short or very short flights. Some countries have already decided to overtax them (Austria, Belgium) or to ban them when railway alternatives exist (Austria, France).

However, is this an effective measure to reduce the impact of air transport on the climate? The argument in this regard is that short flights are inefficient because of all the energy required for take-off and landing, compared to the cruise phase. While this is true, the fact remains that ultimately the impact of air transport on the climate depends mainly on the amount of fuel consumed, and this amount increases with the distances travelled. In other words, it may be absurd to fly 200 km, but flying 200 km consumes less fuel, and therefore contributes less to climate change, than flying 2,000 or 10,000 km.

Short flights, long flights: what impact?

The question then is to know how the climate impact of air transport is distributed between short flights (very numerous but each less emitter of greenhouse gases) and longer flights, far fewer but each much more emitter, d as the planes used are larger and therefore heavier.

To answer this question, we estimated the amount of fuel consumed by all flights departing from 31 European countries. For this area, flights of less than 500 km represent 28% of departures but 6% of kerosene consumed. Conversely, flights of more than 4,000 km represent 6% of departures but 47% of kerosene consumed. In other words, globally speaking, the climate impact of European air transport comes much more from long-haul flights (which no TGV will replace) than from very short flights and other leapfrogs. Discouraging or prohibiting very short flights will therefore only have a minimal effect on the climate impact of air transport.

physical realities

These results call into question the timid public policies in which some countries have embarked. Banning long flights would otherwise be politically more difficult, although only a minority of the population travels by plane (for example, less than half of US residents in 2018).

These results also challenge the way public policies are designed: are the governments and advisers who fight against very short flights ignorant of the physical realities of climate change? Or are they deliberately carrying out a policy officiating as a smokescreen allowing them to affirm that “we have done something” and that “it is a first step”?

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