France's CMA CGM has reduced CO2 emissions by 50% over the last 10 years.
It said emissions are down to 60 grammes of CO2 per teu transported, compared to 120 grammes in 2005.
The owner's most efficient ships only emit 37 grammes.
It claimed shipping was now 70 times less polluting than air transport.
"CMA CGM has improved its vessels hydrodynamics to reduce their emissions," it said.
