Is it possible to make flying sustainable?
To stabilize global mean temperature, we need to get our emissions to net zero, i.e., anthropogenic CO2 emissions must be balance with anthropogenic removals of CO2. To reach this goal, we need to have significant and unprecedented emission reductions.
Aviation is responsible for about 2 % of global CO2 emissions, and the emissions are projected to grow as number of passengers and the length of flights increase. There are some ideas how to replace fossil fuels with biofuels or electricity as the power source for aviation, but these initiatives are currently not economically feasible nor cannot, at least not yet, be scaled to make aviation sector carbon neutral. Other traffic sectors offer more cost-effective emission reduction options (https://ilmasto-opas.fi/en/ilmastonmuutos/videot-ja-visualisoinnit/-/artikkeli/b4df9633-7e1f-4389-9dd0-a0539588f211/visualisoinnit.html#globaalit-paastovahennyskeinot).
The most likely way to make aviation sustainable from the climate change perspective is to compensate emissions with removal of atmospheric CO2. This could mean afforestation and reforestation first, and later other carbon dioxide removal methods later. Since these technologies are challenging to implement at the massive scales required and very expensive, this would likely increase the price of flight tickets significantly. If the passengers paid the full price of removing CO2 from the atmosphere and storing it safely and permanently, aviation could however be considered sustainable. On the other hand, many of the current emission offset programs for aviation emissions are unlikely to be sustainable in long-term and also their effects are difficult to verify.
More information on alternative fuels and plans to halt the increase of aviation emissions can be found for example on a report of International Civil Aviation Organization (ICAO): https://www.icao.int/Meetings/EnvironmentalWorkshops/Documents/2011-SUSTAF/SUSTAF_Review.pdf
Do we need to stop travelling by plane or can we still fly to other countries?