A 45,000-year-old log discovered during excavation of a new power plant could explain a mysterious global event that may have dramatically altered Earth’s climate.

Scientists in New Zealand believe the 60-ton log could hold the answer to the ancient Laschamp Event – where the earth’s north and south poles switched with each other 40,000 years ago.

The 60-ton Kauri log was found nine meters below the surface in Ngāwhā on New Zealand’s north island in February, and was handed over to local Maoris on Wednesday following a major excavation operation.

Top Energy, the company that builds the power plant, started digging in 2017 and dug 900,000 cubic meters of soil before accidentally finding a 16-meter log.

Scientist Alan Hogg, from the University of Waikato, identified the tree as 40,500 years ago, the NZ Herald reported.

The age of the mammoth log has intrigued scientists studying the Laschamp Event – a ‘magnetic inversion’ where the Earth’s north and south magnetic poles swap places.

It is not known exactly when the reversal occurred but it is thought to have been around 41,000 years ago.

The scientists hope that studying the levels of radiocarbon in tree rings will allow them to determine when and for how long the reversal occurs.

Kiwi scientists believe that a magnetic field reversal – and a decrease in the strength of the Earth’s magnetic field, which allows more solar radiation to reach the Earth’s surface – could have a major effect on climate.

“This tree is critical, we’ve never found one of this age before” said Mr Hogg, adding that finding the tree was a stroke of luck and this will play a huge role in future research.

Given its size, the tree was probably 1500-2000 years old when it died, Mr. Hogg said.

The 16-meter-long log was transported to the nearby Ngāwhā Marae (sacred site), where a ceremony to welcome the old tree to the care of the hapū (a division of Maoris) was held.

Ngāwhā Trusists committee chairman Richard Woodman said it was a ‘great acknowledgment’ from Shaw that the tree had been returned to its rightful owner and not as a gift.

Transporting trees is a huge undertaking, with sections about 1.5m long that need to be cut off at both ends to be able to move. The stump alone weighs 28 tons.The three sections were lifted by two 130-ton cranes, then carried by five-foot kimolet trucks dow