In the depths of a Chilean rainforest stands the ‘Gran Abuelo,’ an approximately 5,400-year-old tree fighting for survival. A highway project now threatens its existence — and the ecosystem around it.
Empires have risen and fallen, languages have been born and forgotten — but this tree stood the test of time: The 5,400-year-old Gran Abuelo, or great grandfather in Spanish.
Jonathan Barichivich, a renowned Chilean scientist working in France, grew up in the temperate rainforest now protected in Alerce Costero National Park. His grandfather, Anibal, discovered the Gran Abuelo tree in 1972 while working as a park ranger. That moment, he says, changed the course of his family’s history — and the tree’s.
“I took my first steps in this forest with my grandfather. He taught me the names of the plants before I could even read,” Barichivich recalled. “The memories of my childhood are fuel for my scientific passion.”
Now, Barichivich and his mother, along with a team of researchers, are unlocking the secrets stored in the Gran Abuelo and other trees — information that could shape how we understand and fight climate change.
Not just old, but record-keeper of climate patterns
The alerce trees in this forest , also known as Patagonian cypress, or Fitzroya cupressoides, don’t just grow older than many other trees. The species is also one of the most climate-sensitive trees in the world. Each ring inside its trunk is a yearly weather record. Studying their rings allows researchers to reconstruct climate patterns stretching back thousands of years — data unmatched by any other species in the region.
“They are like encyclopedias,” said Rocio Urrutia, a Chilean scientist who has studied these trees for decades. Her research has helped reconstruct temperature records going back 5,680 years.
To determine a tree’s age, scientists frequently use a tool called an increment borer to extract a part of the trunk and count the number of rings that have formed over the years. However, many old trees have long lost the core of their trunk, so scientists have to rely on both the rings they can see, as well as statistical models that project the total number of rings, to come up with a range for the tree’s age.
The scientists also measure how much carbon the forest absorbs and emits. The more the tree grows, the thicker the space will be between each tree ring. And more growth means more carbon capture. These measurements are essential in understanding how forests respond to global warming.
“Forests absorb about one-third of our carbon emissions,” Barichivich explained.
But will that also be the case as the planet continues to grow hotter?
Understanding how trees grow under different weather patterns tells us how much carbon they absorb — which is essential for predicting whether forests can continue to slow global warming in a hotter future.
A new road is threatening the rainforest
But the centuries-old trees have come under threat, as the Chilean government has proposed reopening an old logging road to build a new highway — cutting through a protected national park.
Officials argued the road would connect cities and boost tourism in the region. However, some say this is just smoke and mirrors.
“Connectivity is not the real reason,” Barichivich told DW, adding that there is another existing road nearby. But this proposed new road would link “directly to the port of Corral — used by one of Latin America’s largest pulp exporters.”
The real goal seems to be opening access to timber, many locals say.
Alerce trees are highly valuable due to their durable high-quality, straight-growing wood.
Researchers like Urrutia warn that the road will increase the risk of wildfires. She said that over 90% of fires in the region start near roads.
This is a global phenomenon. In the Amazon, nearly 75% of fires start within five kilometers (about 3 miles) of a road, and in the US, 96% start within 800 meters.
“The Alerce is an endangered species,” Urrutia said. “Every individual tree counts. A major fire could wipe out the last populations.”
Pushing back to save trees, ecosystems
The scientists turned to Science magazine, one of the world’s top academic journals, warning of the danger.
Their findings — clear, urgent, and backed by years of data — were distilled into a single report, published as a letter.
But “it wasn’t just a letter,” Urrutia said. “It was years of research, fieldwork, and community engagement.”
It struck a chord across the global scientific community, prompting researchers around the world to speak out. Combined with pressure from local residents, it was enough to make the government back off — for now.
