Shipping companies to pay for carbon dioxide produced by vessels

Vessels will be subject to a charge on their greenhouse gas emissions, increasing after a certain threshold, and will also be able to trade carbon credits with one another. This is intended to encourage them to adapt their ships to use low-CO₂ fuels and to operate more efficiently, for instance by slowing down and thereby using less fuel, instead of the current wasteful practice of rushing to ports then idling nearby.