Gravitational Torque Identified as Primary Driver of Decadal Day-Length Shifts
A new study published in Nature identifies gravitational torque between Earth's inner core and mantle as the primary driver of multidecadal changes in the length of a day. Researchers Huifeng Zhang and Mathieu Dumberry found that this gravitational influence competes with electromagnetic and topographic coupling, which act as buffers. These deep interior interactions have altered the day's length by several milliseconds between the early 1970s and 2021, providing new constraints on the physical properties of Earth's deep layers.
