on atmospheric changes to Earth from 42,000 years ago
Ancient swamp kauri tree rings have shed light on crucial changes to the Earth's atmosphere, which may have led to mass extinction of megafauna and the beginning of cave art.
Scientists from NIWA, the University of New South Wales Sydney (UNSW), the South Australian Museum, and the University of Waikato, have been working together on the study.
They looked at what was happening just before the event known as the Laschamp Excursion - the last time when the magnetic poles switched (north became south, south became north). This period lasted about 800 years, before the poles then flipped back.
Research up until this point has been particularly focused on the Laschamp Excursion.
It has looked at what that did to the Earth, and found that at the time, the magnetic field was about 28 percent of present-day strength.
But the new research showed that the most tumultuous period was in the build up, as the poles migrated across the face of the earth.