In an isolated valley in southern Chile, a lone alerce (larch) tree towers above the canopy of an ancient forest.
Green shoots sprout from the crevices of its thick, dark trunks, crowded together like the pipes of a great cathedral organ, and water trickles down its lichen-speckled bark to the forest floor from the bulbous knots in the wood.
“It was like a cascade of green, a great presence before me,” recalls climatologist Jonathan Barichivich, 41, of the first time he encountered “Gran Abuelo” (Great Grandfather) as a child.
Barichivich grew up in the Alerce Costero national park, 800 km south of Chile’s capital, Santiago. It is home to hundreds of alerce trees, Fitzroya cupressoides, slow-growing conifers native to the cold, wet valleys of the southern Andes.
“I never thought about how old Big Grandpa might be,” he said. “Records don’t really interest me.” However, Barichivich’s groundbreaking study has shown that the 30-meter giant could be the world’s oldest living tree.
In January 2020, he visited Great Grandfather with his mentor and friend, dendrochronologist Antonio Lara, to sample the trunk.
They could only get to 40% of the tree, as its center is likely rotten, making it impossible to get a complete core. However, that sample yielded a finding of about 2,400 years.
Undeterred, Barichivich set about devising a model to estimate the age of the Great Grandfather.
Taking the known ages of other larches in the forest and accounting for climate and natural variations, he calibrated a model that simulated a range of possible ages, producing a staggering estimate of 5,484 years old.
That would make it more than six centuries older than Methuselah, an eastern California thistle pine recognized as the world’s oldest non-clonal tree, a plant that shares no common root system.
Some clonal trees live longer, such as Sweden’s Old Tjikko, a Norway spruce believed to be 9,558 years old.
Barichivich believes there is an 80% chance that the tree has lived more than 5,000 years, but some colleagues have dismissed the results. They claim that complete, countable tree ring cores are the only accurate way to determine the age.
The climate scientist expects to publish his research early next year. He will continue to refine his model but is moving away from the “colonialism” present in the field.
“Some colleagues are skeptical and don’t understand why we have revealed the finding before formally publishing it,” he says.
“But this is post-normal science. We have very little time to act: we can’t wait a year or two; it might already be too late.”
Barichivich believes the ancient trees can help experts understand how forests interact with climate.
“Great Grandfather is not just old; it’s a time capsule with a message about the future,” he said. “We have a record of 5,000 years of life in this tree alone, and we can see the response of an ancient being to the changes we’ve made to the planet.”
In January, Barichivich, who works at the Laboratoire des Sciences du Climat et de l’Environnement in Paris, won a €1.5 million (US$1.4 million) European Research Council seed grant that he describes as the “holy grail” for a scientist.
He has embarked on a five-year project to assess the future ability of forests to sequester carbon, hoping to add tree-ring data from thousands of sites worldwide to climate simulations for the first time.
More than a third of the planet’s land area is covered by forests, which capture carbon dioxide during photosynthesis, but current models can only estimate 20 to 30 years into the future.
By adding data on xylogenesis, the formation of wood, Barichivich believes it could provide 100-year predictions of climate change and revolutionize our ability to understand and mitigate its effects.
“If tree rings are a book, for 40 years, everyone has just been looking at the cover,” he says.
THE TREE IS SLOWLY DYING
In an office surrounded by varnished specimens, brittle cores, and wood chips, Barichivich’s mentor, Antonio Lara, 66, has devoted his career to reconstructing temperature, precipitation, and watershed levels throughout history.
Lara, a professor at the Faculty of Forestry Sciences and Natural Resources at the Universidad Austral de Chile in the southern city of Valdivia, has demonstrated that alerce trees can absorb carbon from the atmosphere and trap it for 1,500 to 2,000 years in standing dead trees.
Buried alerce trunks can retain carbon for more than 4,000 years.
He has also identified accurate climate events by translating tree rings into numbers, which can be read like a bar code.
“The Great Grandfather tree is a miracle for three reasons: that it grew, that it survived, and that Jonathan’s grandfather found it,” Lara says.
In the mid-1940s, Barichivich’s grandfather, Aníbal Henríquez, came from the southern city of Lautaro to work for the forestry companies that cut down the “lahuan,” as larch trees are known in the indigenous Mapudungun language, his mother tongue.
He became the park’s first guardian, but many giant alerce trees had fallen victim to loggers before Chile outlawed logging in 1976.
Local populations used alerce shingles as a bargaining chip in the 1700s and 1800s, and wood was commonly used in construction. The famous wooden churches on the island of Chiloé, protected by UNESCO, are built with alerce logs.
Henríquez encountered Gran Abuelo while on patrol in the early 1970s. Although he was initially reluctant to reveal the find, word soon spread, and people began to arrive: now, more than 10,000 tourists descend on the small wooden lookout next to the tree each summer.
Other larch trees in the valley fell victim to loggers or forest fires, leaving the gnarled tree alone.
“Little by little, the tree is dying,” says Marcelo Delgado, Barichivich’s cousin who works at the park as one of five full-time rangers.
“People jump off the platform to tear off the bark and take it as a souvenir.”
The trampling around the tree’s base has also damaged the thin layer of bark on its roots, affecting nutrient absorption.
After tourists vandalized 29 other trees, Chile’s National Forestry Corporation, which manages the country’s national parks, closed the trail indefinitely.
Barichivich hopes that by demonstrating that Gran Abuelo is the world’s oldest tree, he can sound an alarm about the urgency with which we must protect the natural world.
Although the scope of his research is much broader, Barichivich insists that the national park he grew up in is his place.
When he was eight years old, his grandfather disappeared on a routine patrol in the snow. His body was found two days later. Another uncle, also a ranger, later died in the park.
“It seems to be a family tradition,” Barichivich said. “The same fate probably awaits me, to die with my boots on in the woods. But first, I want to unlock its secrets.”
With information from Ciencia en Chile