Ymysg rhai o'r ffynonellau mwyaf o allyriadau yng Nghymru yn 2010 roedd cynhyrchu trydan (25% o gyfanswm y nwyon tŷ gwydr), cludiant ffordd (12% o gyfanswm y nwyon tŷ gwydr), hylosgi preswyl ar gyfer gwresogi a choginio (10% o gyfanswm y nwyon tŷ gwydr), a hylosgi diwydiannol ar gyfer gwres a thrydan o fewn y sector busnes (7% o gyfanswm y nwyon tŷ gwydr).
The largest sources of emissions in Wales in 2010 included electricity production (25% of total GHGs), road transport (12% of total GHGs), residential combustion for heating and cooking (10% of total GHGs), and industrial combustion for heat and electricity in the business sector (7% of total GHGs).