A perfectly preserved ancient log for thousands of years could hold to kickstarting ‘wood vaulting’ – a climate solution where non-commercial viable timbers, including trees destroyed by disease or fire, old furniture or construction demolition — are buried to stop decomposition.
It comes as a team of researchers led by University of Maryland Atmospheric and Oceanic Science Professor Ning Zeng had been studying a 3,775-year-old log and its excavated soil. Their analysis, published in the Science journal last week, revealed that the log had lost less than 5% carbon dioxide from its original state thanks to the low-permeability clay soil that covered it.
People tend to think, ‘Who doesn’t know how to dig a hole and bury some wood?'” Zeng said. “But think about how many wooden coffins were buried in human history. How many of them survived? For a timescale of hundreds or thousands of years, we need the right conditions.”
Professor Ning Zeng, University of Maryland Atmospheric and Oceanic Science Professor who led the study
Professor Zeng discovered the 3,775-year-old log—a “kind of miraculous” find—during a wood vaulting pilot project in 2013, when researchers dug trenches to bury timbers in Quebec, Canada. “The wood is nice and solid,” Professor Zeng told the University of Maryland press on Friday. You could probably make a piece of furniture out of it.”
When the excavator pulled a log out of the ground and threw it over to us, the three ecologists I had invited from McGill University immediately identified it as Eastern red cedar,” Professor Zeng recalled. “You could tell how well it was preserved. I remember thinking, ‘Wow, here’s the evidence we need!’
While past studies analysed old wood samples, they overlooked the soil…
“There is a lot of geological and archeological evidence of preserved wood from hundreds to millions of years ago, but the focus of those studies was not ‘How we can engineer a wood vault to preserve that wood?'” Professor Zeng said. “And the problem with designing a new experiment is that we can’t wait 100 years for the results.”
Shortly after the dig, collaborators at the Ministry of Agriculture, Fisheries and Food (MAPAQ), a government department in Montreal, conducted carbon dating to determine the age of the timber.
In 2021, Distinguished University Professor Liangbing Hu from the university’s Department of Materials Science and Engineering helped Professor Zeng analyse the 3,775-year-old sample’s microscopic structure, chemical composition, mechanical strength, and density. They then compared those results to a freshly cut Eastern red cedar log, which revealed that the older sample had lost very little carbon dioxide.
The type of soil covering the log was the key reason for its remarkable preservation. The clay soil in that part of Quebec had an especially low permeability, which prevented or drastically slowed oxygen from reaching the log while also keeping out fungi and insects, the decomposers typically found in soil.
Because clay soil is common, wood vaulting could become a viable and low-cost option in many parts of the world.
As a climate solution, Professor Zeng said wood vaulting is best paired with other tactics to slow global warming, including reducing greenhouse gas emissions. As he and his colleagues continue to optimize wood vaulting, he looks forward to using what they’ve learned to help curb climate change.
It’s quite an exciting discovery. The urgency of climate change has become such a prominent issue, so there was even more motivation to get this analysis going.
Professor Zeng on the importance of wood vaulting in driving climate solutions.
In July, Wood Central revealed that US foresters are removing excess vegetation from private land and burying it underground.
Scientists and climate tech companies say wood vaulting could help store some of the carbon dioxide equivalent, in the form of flammable vegetation, that the Forest Service must deal with in the coming years — an estimated 2.2 billion metric tons. That’s roughly as much CO2 as cement production worldwide emitted in 2016 and as much as forests globally removed from the atmosphere last year.
“There’s more wood in the forest than markets for it to go,” said research forester Nate Anderson, who studies product supply chains for the Forest Service’s Rocky Mountain Research Station in Missoula. Valuing the carbon stored in wood vaults could change that.
If done properly, burying the debris could help limit the release of greenhouse gases that warm the atmosphere and contribute to climate change. “I don’t see any reason why it can’t be quite significant and reach millions of tons of carbon dioxide sequestered per year in the US alone,” said Sinéad Crotty, the director of the nonprofit Carbon Containment Lab.
Daniel Sanchez, a professor who studies CO2 removal at the University of California, Berkeley, agrees. “Wood vaulting is a newly emerging approach that we think is relatively low-cost and scalable.”
Already, investors including Bill Gates, have poured millions of dollars into jumpstarting wood vaults in recent years – with a number of smaller sites already set up in Maryland, Nevada, Texas, and Colorado.
- To find out more about Wood Vaulting, click on Wood Central’s special feature.
