If you don't believe excess carbon in the air/atmosphere is having a negative effects on the planet, here's an experiment you should try. Clear out your two/three stall garage of all the crap you haven't used in the last three years, pull the most used family car back in, and start it up. Close the garage doors, and fire up the barbie. But wait, don't run off, rather gather the family in the garage, and invite a few of your closest friends for some good old fashion dead burnt flesh......then muliply the effects by say 2 billion, given the number of humans on the planet That is just one days worth........Weee just ventng