Sigh. You know what, I actually tried to find a better term than "governing body" but at the end of the day, I didn't really find an alternative that wouldn't immediately get some peanut objecting to its exactness, so I went with governing body. Thankyou for being the peanut. So, international politics 101. The UN is a body whereby the nations of the planet can get together and discuss global problems and their solutions. This type of body did not exist 1500 years ago. Yes, like any reasonably well-educated adult on the planet I'm aware that the UN can't make laws, and couldn't enforce them if it did. But in the real world there are other means available to the UN to pressure member states to do the right thing. If 99% of nations voted for a new calendar, the remaining 1% are going to look pretty silly if they stay on the old calendar.

As for y2k, you know what, I could have stuck a load of different examples in there. Changes to http for example. Or how about the switch from national currencies to the Euro in Europe. Each one is different, but they all demonstrate that important changes can be made to large interconnected systems, and that the change can be activated at the flick of a switch if the need for synchronisation exists. Also, I assume you're too young to know much about y2k if you can talk so blithely about people working independently in an uncoordinated manner. Y2k was huge - if you change one system to requiring 4 digit years, but just one of the systems it communicates with requires two digit years, your system stops working. Both need to switch to 4 year dates on that interface simultaneously. When the systems you're talking about are command and control circuits, financial transfer systems etc, this was a major issue.