Start doing the time warp: The International Earth Rotation and Reference Systems Service announced that a leap second has been added to the last day of 2016, according to The Verge.

Leap seconds preserve the accuracy of atomic clocks and compensate for variations in the Earth's rotation.

The tides are gradually slowing down the Earth's rotation, a phenomenon astronomers refer to as their "braking action," the U.S. Naval Observatory reported.

Leap seconds reconcile atomic clocks with the slowing rotation; they have been added 26 times since the system was introduced in 1972, according to the USNO.

Why now?

The warm, dense water of El Niño contributed to this year's slowing of Earth's rotation, U.S. Naval Observatory spokesman Geoff Chester told the Associated Press. (Particularly strong earthquakes and the pull of the Moon's gravity can also contribute to the deceleration of Earth's spin.)

Leap seconds can cause computer glitches in theory, but the last one (on June 30, 2015) didn't venture into Y2K territory because engineers were well prepared, Gizmodo reported.

On a practical level, it's just a little more time.

After 11:59:59 on Dec. 31, the clock will tick 11:59:60 — an extra second to linger in an awkward New Year's kiss or just more of 2016 to love. 😉

[h/t the Verge]