The merchant fleet is divided into five categories, each of which has a filter and a CO2 and freight counter for the hour shown on the clock. The ship types and units are as follows:
- Container (e.g. manufactured goods): number of container slots equivalent to 20 feet (i.e. a 40-foot container takes two slots)
- Dry bulk (e.g. coal, aggregates): combined weight of cargo, fuel, water, provisions, passengers and crew a vessel can carry, measured in thousand tonnes
- Tanker (e.g. oil, chemicals): same as dry bulk
- Gas bulk (e.g. liquified natural gas): capacity for gases, measured in cubic metres
- Vehicles (e.g. cars): same as dry bulk
UCL EI took data showing location and speed of ships and cross-checked it with another database to get the vessel characteristics, such as engine type and hull measurements. With this information they were able to compute the CO2 emissions for each observed hour, following the approach laid out in the Third IMO Greenhouse Gas Study 2014. Kiln took the resulting dataset and visualized it with WebGL on top of a specially created base map, which shows bathymetry (ocean depth), based on the GEBCO_2014 Grid (version 20150318), as well as continents and major rivers from Natural Earth.