In response to climate change, Germany’s Christian Democrats proposed doubling taxes on domestic flights to reduce CO2 emissions. The plan would exempt connecting flights (part of long-haul trips) so the impact would only be on the current tax of $8.10 per ticket for domestic flights.

The suggestion was made last month by the leaders of the Christian Democrats party, part of a coalition that includes the Christian Social Union and Social Democrats. The proposal also notes planes using non-fossil fuel-derived energy would be exempt.

“We will invest, together with the aviation industry, to make electric-powered flight standard for short-haul flights and to create synthetic fuel to achieve climate neutrality on medium- and long-haul flights,” states the proposal, according to the BBC.

The proposal comes amid growing criticism of the airline industry’s global contribution to CO2 emissions. Earlier this year, Responsible Travel issued a statement saying the aviation industry was one of the fastest-growing contributors to greenhouse gas emissions. The statement challenged the world’s governments to take action and raise taxation, among other steps.

“If we are to achieve the necessary global cuts in emissions, the aviation industry cannot rely on other sectors to take on the burden of reductions. Aviation needs to play its part and tackle its own emissions,” stated Responsible Travel.