Once upon a time... Actually, not all that long ago, human beings were divided into tribes. Survival depended on small groups of individuals living and working together to hunt, gather, raise children, migrate when needed, etc. The distinction between "us" and "them" - those who were not of the tribe, was clear. Tribes certainly cooperated, interbred, and, of course fought. But the survival of the few in the tribe depended on the few, and was not greatly affected by tribes even a hundred miles away.
Tribes evolved into city-states, then empires and colonies, and finally, the collection of nation-states we have now. (Yes, I'm oversimplifying a few thousand years of history into one sentence.) And now, the struggles and survival of people thousands of miles away have very definite effects on us. This is unprecedented in history.
These reflections come from thinking about Israel and Palestine. In some ways, this long-time struggle between two badly-matched tribes has been in basically active conflagration since 1967, with a few moments of calm over that last 45 years. I mean badly-matched in that one, Israel, has had enormous of power over the other, was created by a colonial power, and is supported by arguably the biggest power on Earth (that would be us.) The origin and reasons for this conflict are many, and I won't even try to describe more than 60 years of history and analysis here. But one thing is clear: this one conflict (and our role in it) has had enormous effects, some of which include effects close to home: dead people in Manhattan.
A friend of mine has been an advocate for the "one state" solution for a very long time, long before Michael Lerner published a book about it. I would go further. It's time for the world to be one state. It's time we finally realized that we're all in it together, and have to actually work together to survive.
Gone is the time when the activities of one nation-state across the planet had little or no effect on other nation-states. Gone is the time when there was enough resources that it didn't matter who used what where. Desertification in parts of China affects air quality in California. Burning coal in the US or Russia melts glaciers, raising the sea level world-wide. We can't escape the fact that we all affect each other in ways unknown even a hundred years ago.
It's time that we finally understand that we are in this together, as one human species. I know - you say this is messy. The "United States" can barely pull it off - how could we manage to pull it off worldwide? I don't have a good answer - but I know one thing. If we don't, we're doomed.