Yn rhannol oherwydd treftadaeth ddiwydiannol Cymru o fewn y sectorau dur, olew, nwy a chemegau yn ne Cymru, mae busnesau yng Nghymru yn gyfrifol am tua 20% o allyriadau carbon diwydiannol a busnes cyffredinol y DU – gellir priodoli'r rhan fwyaf o allyriadau carbon diwydiannol a busnes Cymru yn uniongyrchol i gwmnïau ar hyd coridor yr M4.
Due in large part to Wales’ industrial heritage within the steel, oil, gas and chemicals sectors in south Wales, Wales-based businesses are responsible for around 20% of the UK’s overall industrial and business carbon emissions – the majority of Welsh industrial and business carbon emissions can be directly attributed to companies along the M4 corridor.