Global ethic?

In relation to an earlier post, is the notion of a global ethic feasible, or are we destined to continue with multiple ethics? If we do adopt a global ethic, how much of it would be dependant on religion? Or would the transcending of religion play a big part in adopting a united ethic as opposed to a pluralist model? Who woulod have a say in such discussions? Would it be democratic, or more authoritarian? Who would we grant such authority to?