Aside from polluting oil spills and acoustic disruption of marine wildlife, the International Council on Clean Transportation (ICCT) estimates that international shipping emitted 812 million tonnes of CO2 in 2015. If shipping were a country, it would rank sixth, just ahead of Germany, if you compare it to country-level anthropogenic CO2 emissions. Without drastic action, CO2 emissions from international shipping could increase by up to 250 per cent by 2050, warns the International Maritime Organisation (IMO).