Global shipping, which is fuelled predominantly by marine diesel, belches out around 3% of planetary greenhouse gas emissions, making the sector a bigger polluter than aviation. The lo-fi method involves funnelling ships’ exhaust fumes through calcium oxide pebbles, also known as quicklime. A three-week ocean-going trial showed that Seabound’s method can hoover up 78% of a ship’s carbon emissions and 90% of toxic sulphur exhaust fumes. Seabound’s system comes at a time when efforts to reduce the shipping sector’s emissions are all at sea. Last month, a landmark deal to cut global shipping emissions was scuppered by the Trump administration, which threatened smaller countries with tariffs if they signed up.