The was a message today in a C++-related e-mail list saying that the October meeting of the General Conference on Weights and Measures (CGPM) will consider getting rid of leap seconds and adding a leap hour every few thousand years.

At present, because of the Earth’s variable rotation around its axis, atomic clocks (which UTC is based on) are getting ahead of astronomical observations.  To keep the two more or less in sync, one second is added to or subtracted from UTC every so often.  In principle, this can happen to the last minute of June or December in any given year; but in practice, it happens much less often.  Twenty-eight leap seconds have been added since December of 1971; but there hasn’t been one since December of 2016; and so far, there has never been a negative leap second.

Unfortunately, there’s lots of software out there that pays no attention to this; and leap seconds (23:59:60 should be considered a valid time) have caused outages even though it’s been happening for over fifty years; and it looks like we might have a negative leap second before long (23:59:58 should jump directly to 00:00:00 on some date known in advance) which could cause even more craziness.

We’ll see what CGPM decide to do …