Caiff y chwe nwy tŷ gwydr eu mesur fel a ganlyn:Caiff allyriadau o garbon deuocsid, methan ac ocsid nitraidd eu mesur yn unol â'r flwyddyn sylfaen sef 1990,Caiff allyriadau o “nwyon f” sef: hydrofflworocarbonau, perfflworocarbonau a sylffwr hecsafflworid eu mesur yn unol â'r flwyddyn sylfaen sef 1995.
The ‘basket’ of six greenhouse gases is measured as follows:Emissions of carbon dioxide, methane and nitrous oxide are measured against the base year 1990,Emissions of “f-gases”: hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride are measured against the base year 1995.