There are still about a third of people who believe in AGW. If all of them stop using electricity and eating most foods like meat, and stop showering etc (which shouldn't be too much of a concession for many of these sorts) it will reduce more greenhouse gas than a 20% reduction amongst everyone would. (With the caveat that their reduction in carbon footprint might be mitigated by their BO.) It all depends on their green religious conviction and willingness to rebel against the modern lifestyle. Of course law enforcement and security will have to be beefed up in case any of them get jealous of us sceptics as we continue with our normal way of life and drive around in even larger SUVs just to rub it in.