Magnetic pole reversal indicated in 42,000 year old tree rings may have triggered global environmental change Social Sharing CBC Radio · Posted: Feb 19, 2021 4:15 PM ET | Last Updated: February 19 Tree rings from the ancient Kauri tree in New Zealand showed a spike in radioactive carbon indicative of a magnetic pole reversal(Nelson Parker) comments Quirks and Quarks8:01When the magnetic poles flip out, Earth seems to suffer The Earth's magnetic poles have flipped many times in our planet's history - and while we know this is an important geophysical event, we haven't had any good evidence to indicate whether it's an important biological event.