When I read the Nature abstract I was startled to read this:
"This multidecadal periodicity coincides with changes in several other geophysical observations, especially the length of day and magnetic field."
Well, just last year a record was set for shortest day ever. Elsewhere I read this:
"Earth's magnetic field is rapidly getting weaker, and geophysicists don't know why. The decrease in strength--a startling 10% in the last 160 years--could signal that the magnetic field is starting one of its sporadic flip-flops."
"Today, the dipole is weakening so quickly that it would vanish within 2000 years if the current rate continues. Some scientists have wondered whether this is the early stage of a reversal, because the field has been stable for an unusually long 780,000 years."