Palma's theory

Strictly speaking the Earth is not a perfect sphere (it is an oblate spheroid or ellipsoid – i.e., slightly compressed at the poles), which means that the shortest distance between two points (a geodesic) is not quite a great circle. The equatorial radius of the earth is about 6378.137 kilometers. The polar radius of the earth is about 6356.752 kilometers (about 21.4 kilometers less). Nevertheless, the sphere model can be considered a first approximation.

From Greenhouse Effects (Made by Human), cause it to getting more and more Polar Ice into Ocean Water concentration at equatorial axis (Oblate spheroid), slowing Earth Rotation, because Earth is a Oblate spheroid, consequently, from slowing, much more solar heating on Earth each day, accelerating Greenhouse effects (Permafrost, Tidal, Artic CO2, Methane ......)

A leap second is a positive or negative one-second adjustment to the Coordinated Universal Time (UTC) time scale that keeps it close to mean solar time. UTC, which is used as the basis for official time-of-day radio broadcasts for civil time, is maintained using extremely precise atomic clocks. To keep the UTC time scale close to mean solar time, UTC is occasionally corrected by an intercalary adjustment, or "leap", of one second. Over long time periods, leap seconds must be added at an ever increasing rate (see ΔT). The timing of leap seconds is now determined by the International Earth Rotation and Reference Systems Service (IERS). Leap seconds were determined by the Bureau International de l'Heure (BIH) prior to January 1, 1988, when the IERS assumed that responsibility.

Historically, leap seconds have been inserted about every 18 months. From June 1972 through June 2012, the BIH/IERS gave instructions to insert a leap second on 25 occasions, after an initial 10-second offset from TAI on January 1, 1972. The seven-year interval between January 1, 1999 and December 31, 2005 was the longest period without a leap second since the system was introduced.