Vegetation in general, and trees in particular, work in the same way as chemical 'scrubbers' aboard spacecraft or submarines, to remove excess carbon dioxide from the atmosphere. Accordingly the Kyoto Protocol permits signatory nations to set new forests against emissions. ESA's Kyoto-Inventory service, forerunner to GSE Forest Monitoring, utilises satellite data to assist national annual Kyoto reporting on afforestation, refforestation and deforestation (ARD).