Dr. Aykut Mert Yakut:

The logic is that they are regulated by the ETS and there is a market for carbon pricing. The EU reduces the number of total allowances every year. For instance, beyond 2020 in the air transportation sector, annual allowances will be decreased by 2.2% annually until 2030.

As the cost of the EU ETS will increase, the burden of carbon emissions on the sector will be higher in the future, relative to what it is today. As they are regulated by other markets within the European Union, there are national plans in every EU country.