The leader of the German left-wing party Die Linke on Saturday suggested nationalizing airlines to better combat climate change, injecting leftist ideas into the current political debate that were quickly rejected by more moderate parties.

"Airlines belong in state hands - just like the energy supply or the railways," Bernd Riexinger told the Funke media group, adding that something with such grave consequences for the climate must not remain market-based and unregulated.

"Flying used to be better regulated and predominantly in public hands. Fierce competition has been allowed on the aviation market - to the detriment of employees and to the detriment of the climate," he said.

His remarks were met with criticism across the board. "We need a green market economy, not green state capitalism," tweeted Social Democrat politician Karl Lauterbach. Markus Blume, general secretary of the conservative Bavarian CSU called Riexinger's plans "scary."

The climate debate in Germany has mostly focused on whether flying should become more expensive, for example by raising taxes on domestic flights in particular, to lower greenhouse-gas emissions that are considered responsible for climate change.

According to the Intergovernmental Panel on Climate Change (IPCC), the earth has already warmed by about 1 degree Celsius compared to the pre-industrial era, and Germany even a little more.

If current trends continue, the world will likely be 3 degrees warmer by the end of this century. The risk of droughts, storms and other weather extremes is growing, and rising sea levels are already threatening islands and coasts, the IPCC has warned.