Corporations don't just emit greenhouse gases for the fun of it, like some sort of villain, they do it because they produce the stuff that we, the "ordinary citizens" buy like mad every Christmas or whenever we have $200 extra in our bank accounts.
Corporations will do anything permitted by the law and that's no secret. That includes evading taxes, sub-living wages or pollution. Ordinary citizens allow this by buying the products of those corporations and by not voting for more green policies.
To assign the blame solely on corporations and remove "ordinary citizens" from the equation is short-sighted at best.