The first and only thing that comes to mind is the same as on millions of other minds. The emitting of carbon dioxide. All the fun activities emit co2 via burning gasoline. In fact most industries emit co2. most activities involve co2 (or at least driving there). If we could lose the emitting of co2 we would not be facing catastrophic global warming. As a byline;- the mouthwatering odor of a steak on a charcoal barbecue and the effect on the climate change, ah to hell with it, I want one!