A nice little summary of leap seconds and the current state of affairs. But there’s a comment at the end that I think has dropped a minus sign.
Why not just decouple the two clocks, and let them go their separate ways?
A lot of scientists do in fact feel this way. But it turns out to be really, really complicated to do that. A lot of computer systems (including satellite navigation systems) have software written a while ago, and changing that would be difficult and have unforeseen consequences. Fiddling with that may be dangerous.
Decoupling atomic time from earth rotation time requires no fiddling — you just stop inserting leap seconds into UTC. Clocks generally don’t get their cues from earth rotation, they get them from synchronization to official time, which is atomic time (in the US). It’s the fiddling — the insertion of the leap seconds into the atomic time signals — that contains the potential pitfalls.
Having countries change their official time from GMT (which is mean solar time) to UTC would be technologically trivial. It turns out that in the US this happened just a few years ago; the wording describing our time zones was changed from GMT to UTC in the America Competes Act in 2007. Even though the basis for time had been atomic time anyway, it wasn’t official until then, but nothing really changed (as far as I can tell) when the law took effect.
Has the Earth been speeding up its rotation recently? It looks like we’ve been adding fewer leap seconds than we used to:
http://en.wikipedia.org/wiki/Leap_second
From what I understand, yes, we’ve had some speedup events. There’s the weather — droughts and increased precipitation in the right areas redistribute mass, and there’s a long-term effect of the earth “relaxing” from the last glacial period that makes us the tiniest bit less oblate, if I understand what Earth Orientation people have told me. And other small(er) effects as well.
Anthropogenic GLOBAL SLOWING! Impose a Temporal Tax on Everything. Burundi and Zimbabwe do not slow the Earth’s rotation with timepieces or skyscrapers. They will sell formidable sheaves of costly temporal credits to First World abuser countries.
Head Start programs will assure no aspect of government proceeds in a timely manner. Homeland Severity will vigorously confiscate all attempts to smuggle time from the US, including mandatory enhanced cavity inspections of the elderly at airports. Life expectancies must be compassionately reallocated.
Saving Our Children by 2100 requires that patriarchal personal chronometry give way to global governmental horology no matter what the cost or consequences. Obey time hors!
Here’s a link that shows the excess length of day for the last 50 years or so.
http://www.ucolick.org/~sla/leapsecs/amsci.html
So yes, there was a general speedup from ~1993 to ~2003, but the overall rate was still slow as compared to 86400 sec a day until some brief excursions that started in about 2000, but never enough to subtract a leap second.
The length of the day has a number of periodic variations. http://maia.usno.navy.mil/whatiseop.html