Carbon Netrual Companies

How can companies like Sky claim they are carbon neutral when they don’t take into account if their suppliers are also carbon neutral? What about advertisers are all the advertises on Sky carbon neutral, I some how think not and Sky News weather is sponsored by an airline, which although they only make up a small proportion of Co2 levels, the Co2 is released at a high altitude and therefore more damaging to the environment and also is the fastest growing source of pollution.