We need some form of global government to deal with the following issues:
Such a government will probably arise out of the UN. I imagine a senate style government with representatives from each country, where the voting power held by each member is proportional to the number of people they represent - provided there is a functioning democratic structure that put them in place.
Eventually we could move on to a system with a number of members from each of the larger countries (roughly proportional to population) and a minimum of one member from smaller countries. This would require that the members from larger countries be directly elected rather than appointed by their respective national government.
Currently there is nothing to stop large businesses going into third world countries, extracting resources and not paying a fair amount to the citizens of that country, who ultimately own the resource. All they have to do is pay (bribe) the local government or militia enough.