Ugly, initially, if history is any guide. The question is how many rounds of world war there will be, and whether a global revolution will be needed, before we can have a global democracy.

Those whom the Gods wish to destroy They first make mad. -- Euripides

I am not sure forming a global government would solve much. The problem is enforcement. How much commitment can individual countries and companies provide? How the global village will agree on that? I am afraid that practical enforcement will look like an outright war. At least, the meaningful enforcement and in the initial stage.

One organization which does some enforcing protection of the environment is Sea Shepherd. But I hardly know other examples.