> ...the faster it happens the more havoc it is likely to cause. If it happens over thousands of years then humans will adapt to a 'non constant' compass direct

> ...the faster it happens the more havoc it is likely to cause. If it happens over thousands of years then humans will adapt to a 'non constant' compass direction and find other ways to navigate. Actually the more pressing matter regards animals that employ magnetoreception (birds, bacteria even!) where a change like this might be particularly devastating. This of course assumes that there is not already some undiscovered non-genetic mechanism to help with adjusting, say socially or physiologically. Human technology could adapt in at most a matter of decades, while genetic adaptation would takes orders of magnitude longer.