Has this scientist found the world's oldest tree? Experts aren't so sure

A scientist in southern Chile believes he's found the world's oldest tree, a Patagonian cypress he says is over 5,000 years old -- but not everyone is ready to hand the record over yet.

Jonathan Barichivich, a scientist who has studied the tree, named the Alerce Milenario, for two years, told the journal Science that his research proves the 100-foot tall, 13-foot wide tree is the world's oldest.

His research, which is not yet published, challenges the current record -- held by a bristlecone pine in the White Mountains of central California, known as Methuselah. That tree is 4,850 years old, according to Guinness World Records.

However, Guinness World Records is not ready to hand the title over quite yet.

Adam Millward, managing editor at Guinness World Records, told ABC News that he has spoken with the organization's dendrochronology expert about the new findings, and the Patagonian cypress has already been deemed the world's second-oldest species, so there is "no denying its longevity potential."

However, evidence for this specific tree is not yet strong enough, Millard said.

"Given this novel technique of aging trees is yet to be peer-reviewed and more widely adopted by the dendrochronological community, it's our view that it would be premature to recognize these estimates for Alerce Milenario at this time," Millard told ABC News.

"If that were to change in the future, or if new evidence were to come to light, GWR can certainly reassess its claim for the title," he added.

Barichivich said the alerce was discovered in 1972 by his grandfather, a park ranger in Chile's Alerce Costero National Park, approximately 500 miles south of the country's capital, Santiago, according to The Wall Street Journal.

For the last 50 years, Barichivich's family has worked to protect the tree from tourists and pushed to improve conservation measures near the park.

Two years ago, Barichivich and a colleague took samples from the tree by removing three cores from its trunk with a corkscrew-like boring tool, he told The Wall Street Journal.

The cores contain pieces of the tree's growth rings, which can be used to determine a tree's age without causing significant damage to the plant.

Because the Alerce Milenario is so massive, however, normal boring tools weren't enough to harvest the growth rings. Instead, Barichivich's samples showed only a portion of the tree's radius -- not quite enough to determine its age.

Nonetheless, Barichivich studied his samples, finding 2,465 rings on the longest core sample, which accounted for the tree's growth between about 446 B.C. and 2018. According to The Wall SJ, he then used a mathematical model to gauge the tree's likely growth rate during earlier years.

Comparing his model to data from complete cores taken from the alerce trees cut down nearby in recent decades and adding data about environment factors impact on growth rates, Barichivich found the model to be at least 4,100 years old, WSJ reported.

"There is an 80% chance the tree is older than 5,000 years," Barichivich told WSJ, adding that it is "most likely" 5,484 years old.

Peter Brown, director of Rocky Mountain Tree-Ring Research, a nonprofit organization in Fort Collins, Colorado, isn't yet convinced by Barichivich's findings.

This main issue with Barichivich's claim, Brown told ABC News, is that their full methodology has not yet been published, so knowledgeable researchers have not yet been able to evaluate the new claim. He was not involved in Barichivich's research.

"I find that rather worrisome, that for such a bold statement as they have made they did not submit a paper to a peer-review journal for expert evaluation before sending out their press release," Brown told ABC News.

"I always go back to the Sagan quote: 'Extraordinary claims require extraordinary evidence.' So far we've not seen any evidence, let alone that it may be extraordinary," he added.

Brown said claims that large trees are very old are common, yet one can't rely on that correlation until they are able to obtain an entire ring series, which Barichivich was not able to do.

Brown said that especially for trees growing in optimal conditions, like the wet ravine around Alerce Milenario, growth tends to be fast in its early age.

So, while Brown acknowledges that Barichivich's findings present the tree as being among the top 10 oldest confirmed individual trees in the world, he also contends that the tree was reported to be in "poor shape" and could have been affected by wind, fire or lightning in its later years, slowing its ultimate growth.

"Without knowing exactly what sort of extrapolation and the assumptions behind it they used to estimate that inner growth, count me unconvinced for the present," Brown said.

Nathan Stephenson, an emeritus scientist with the U.S. Geological Survey, told ABC News that we may never know if Alerce Milenario is the oldest tree on Earth.

Like Brown, Stephenson said that one would need to be able to get a sample from the tree with each of its rings all the way to the core. However, Stephenson said that even if someone could find a tool capable of harvesting that sample, the tree core could be rotten and there is no guarantee that all of the rings are visible.

Stephenson was not involved in the study.

Nonetheless, Stephenson said this preview to the full research offers a chance for a new claim to the oldest tree in the world.

"There's a reasonable chance that this is the oldest tree on Earth and it deserves more scrutiny to find out," he told ABC News.

Despite the contention around his findings, Barichivich told The Wall Street Journal that the "main motivation" of his work is to raise awareness about protecting trees.

He said that Alerce Milenario is only living on one side and most of its trunk is dead. Between climate change and tourists trampling on their roots, Barichivich said the area trees need further protection.