Too bad it took me two days to notice this thread. This is of interest to me because I have worked in the US financial sector (granted not directly, on the IT side) for many years and some of this crisis happened pretty close to home. I think I have a fairly good grasp of the global economy (even though I can't refute the charge of being "over the ocean") and here it goes:
1) MeEtc is correct noting the euro is part of the problem and Discrate is correct in noting the reason why. One size does not fit all when the GDP and the size of the economies are very diverse. It's a great goal to get there, but the reality and goals are two different things. To be honest, I am surprised that there still are countries trying to join the euro zone. They are still betting on the single currency spurring foreign lending and investment, an idea which really should have gone out the door with the Greece fiasco -- that is *exactly* what happened and
they spectacularly abused it. If anybody controlling large sums of money has half a brain left, this shit will never work again and the newcomers to the euro zone will only experience the negative effects of the common currency restrictions on managing their own economic policy effectively.
2) Cookie is correct that the mess was triggered by the US real estate backed securities crisis (which is not to say it wouldn't have happened otherwise a couple years later). As for the charge about the size of the US debt, he's also correct there, but
this is all you really need to know. Let me know which euro zone country can pull that off. I'm aware both of those are 2010 articles, but nothing has really changed since then.
This takes us back to the original poster's "one world currency." I believe I know what we are talking about and it's not quite that. There is no credible proposal of a single global currency and it would never work. What *has* been proposed is a global reserve currency index. What that means is some kind of a virtual money unit, the exchange rate of which would be based on the blended composite of all currencies that make it up, on any given day. This idea was proposed by by China, Russia and others several years ago, and it would offer greater immunity for everyone to any one country's problems. However, it doesn't seem to have gained any traction whatsoever.