According to a recent report from ABAJournal.com, victims of hurricane Katrina can now officially sue oil companies for the fact that a hurricane hit New Orleans, claiming that, if the suit goes forward, the oil companies themselves were directly responsible for the creation of said hurricane from its Carbon emissions.
While the evidence of global warming is less conclusive then the tobacco - cancer link (the theory is sound, but has never been proven conclusively), the fact remains that the Carbon Dioxide emitted from such plants all over the world are necessary for plants to survive, in order to create more oxygen through photosynthesis. There is a mutualist relationship between human and plant. Humans exhale the carbon dioxide the plants need to survive which, in turn, creates the oxygen humans need to survive.
Ultimately, if the scientists are correct about gas emissions being too high, the simple answer is to plant more trees. Doing so would naturally regulate the atmospheric levels of CO2, without having to create new laws and taxes.