The University of Leeds’ geophysics people have been carefully examining reliable old navigation records and discovering that “These measurements show that since [mid 19th century] the strength of the field has fallen gradually by around 0.05% per year.”
Yes! Once more, it was the magnets that dunnit — the thumping big set lying roughly between the Earth’s poles definitely included. So... careless navigation or dopey technology wasn’t nearly as responsible for maritime losses as was once thought.
Being the troublemaker I was raised to be... I naturally wonder what else has quietly changed scale, rate, speed, length and so on in the last century, millennium or whatever? Particularly without leaving such tracks?