Using GRACE data to estimate climate change impacts on the Earth's moment of inertia

Various contributing components are independently evaluated using five high-quality atmospheric reanalysis datasets and a novelty numerical modeling system. We found a steady, statistically robust (passed a two-tailed t-test at p = 0.04 for dof = 15) rate of MOI increase reaching similar to 11.0 x 10(27) kg m(2)/yr, equivalent to a 11.45 s mu /yr increase in the length of day, during 2002-2017.

Further analysis suggests that the Antarctic ice sheet contributes the most, followed by the Greenland ice sheet, the precipitation-driven land hydrological cycle, mountain glaciers, and the fluctuation of atmosphere, in this order. Short-term MOI spikes from the GRACE measurements are mostly associated with major low/mid-latitude earthquakes, fitting closely with the MOI variations from the hydrological cycle. Atmospheric fluctuation contributes the least but has a steady trend of 0.5 s mu /yr, with horizontal mass distribution contributing twice as much as the vertical expansion and associated lift of the atmosphere's center of mass.