My gas grill is now killing the planet?

Is your grill itself the problem? If you have too little air getting to the flame, it will burn to form CO rather than CO2. CO is far worse than CO2, and is also a health hazard - it bonds to (uses up) haemoglobin (which takes oxygen from your lungs to your body) 200 times better than air. You are producing CO if your barbeque has a yellow flame. I'm not sure what you can do about it - maybe a small portable fan to blow in fresh air? - but that would be an environmental problem. The other problem with propane is that it's denser than air, so if you get a leak, the propane will pool in some depression in the ground, where, being a gas other than oxygen or CO2,it will choke the life if there's enough of it (and be a fire hazard if some smoker drops a cigarette there). Make sure there aren't any leaks - get some water with some washing-up detergent in it, and paint this on all your pipes and tubes, especially around the connections. If it bubbles when the gas is on, you've got a leak.