[ao98]

Even without global warming, Earth has been slowing, mostly because the gravitational pull of the moon has been acting as a brake. Keepers of the master clock at the U.S. Naval Observatory in Washington generally add a leap second to official time every 12 to 18 months to compensate, said observatory spokesman Geoff Chester.

This is a lie. The leap second is not added because the earth is slowing. It is added because the year is not excactly 365-1/4 days long. The leap second is to compensate.

[r9etb]

This is a lie. The leap second is not added because the earth is slowing. It is added because the year is not excactly 365-1/4 days long. The leap second is to compensate.

Well, yes and no. Click here for a description of leap seconds.

The last leap second, BTW, was added in January, 1999 -- three years ago. By historical standards that's pretty long.

[MassLengthTime]

This is a lie. The leap second is not added because the earth is slowing. It is added because the year is not excactly 365-1/4 days long. The leap second is to compensate.

No, leap seconds are indeed added to civil clocks to account for the lengthening of the mean solar day caused by deceleration of the Earth's rotation due to tidal braking.

The last leap second adjustment was made on Jan 1 1999.

See USNO Leap Seconds for the excruciating details.

FWIW, there is currently a proposal to forego leap second corrections altogether, and let civil clocks drift with respect to the mean solar day.