Comment by chgs

If I can make 1 unit of food for €50 and use 50 tons of carbon, or make it for €60 and use 10 tons of carbon, a carbon tax and food subsidy would allow me to sell that €60 low carbon food for €50 and force me to sell the high carbon food for €60

This gives an economic incentive to use the lower carbon method, funded by those who use more carbon, while not changing the end price or output.