Earth’s core is meticulously maintained by the other layers of the planet as the iron from the outer core crystallizes and changes the density of the liquid surrounding it. This change in density creates the churning motions necessary within the inner core to maintain Earth’s magnetic field (per Nature). We, on the surface, don’t realize all of this is happening thanks to the outer core, which separates the Earth’s inner workings from the crust, allowing the core to spin however fast or slow it needs.
So while the Earth’s inner core slowing down and even changing directions may sound like an event of cataclysmic proportions, it’s just the Earth doing Earth things. These changes in pace are to be expected around every seven decades or so, according to the multidecadal study conducted by Yi Yang and Xiaodong Song. Though the inner core is about the size of Mars and is at a depth that makes it nearly impossible to study on a regular basis, so the understanding of the patterns and behaviors it exhibits is always subject to change.
