  Recently published studies suggested that the difference between Universal
and Coordinated Time UT1-UTC could reach a large positive value in a few years,
making it necessary to introduce a negative leap second into the UTC scale for
the first time in its history. Based on the latest UT1 series provided by the
International Earth Rotation and Reference Systems Service (IERS) and its
prediction, it was shown that the tendency to acceleration of the Earth's
rotation observed over past four years most likely will return to the
deceleration, which is the usual behavior of the Earth rotational dynamics
during past decades.
