Explained | Is the Earth’s change in rotational speed a cause for concern?

The story so far: On June 29, 2022, the Earth completed its axial spin at a record speed, shortening the day by 1.59 milliseconds. Dr. Binod Sreenivasan, Head of the Department of Earth Sciences at IISc Bengaluru, explains one of the dominant effects: “The Earth’s magnetic field is produced by convection that occurs in the outer core, creating waves. We can think of these as concentric cylinders that oscillate back and forth, all the way from the inner core to the mantle, creating waves that travel outward…this has been correlated to the length of day for a century now.” He added that in the recent past, the Earth’s rotation has varied between one or two milliseconds and this phenomenon has been termed normal. Speaking of alternate reasons for this change, he said, “To some extent, tidal waves and tidal motion can also contribute to the variations in the length of night and day and can indirectly be associated with climate change.” Another plausible reason could be the melting of glaciers and polar ice caps that result in a change of mass distribution on the surface or interior of the Earth. Concern arises when oscillation happens only in one direction which is unlikely to happen given the past record of these variations “because the Earth’s magnetic field is dynamic.” However, there could be cause for concern if glacial melting occurs rapidly on one side of the Earth.