What difference does a second make? A lot, if you care about what happens on or relative to the Earth by using a watch or a clock.
When the atomic second becam
e the world's standard time interval, the leap second was required to keep civil time synchronized with astronomical events (like sunrise). Universal Coordinated Time accrues elapsed time in atomic seconds. Leap seconds are inserted in Universal Coordinated time when the UTC and astronomical time scales differ by no more than 0.9 seconds. When this happens depends on the mysteries of the variability of the Earth's rotation and orbit.
Now the International Telecommunications Union wants to get rid of the leap second. Telecommunications only care about the UTC broadcast providing standard seconds, one after another like a metronome. Broadcasters need this for frequency calibration. They don't care much what time it is. The leap second is an inconvenience for the ITU. But it is essential for those who operate satellites – and those who use GPS, because GPS time is steered in small increments to match UTC. GPS provides neither a standard time scale nor time interval. We will lose the connection between civil time and Earth rotation if the leap second disappears. Don't worry about the occasional minute with 61 seconds. We accrue time in seconds universally. Minutes, hours, days, months and years are calendrical conveniences, not technical intervals of time.
If you would like to learn more, you can read our editorial
("Time is Money--Again") that ran in this week's Space News
By Dr. David Finkleman