A thousands-year-old log demonstrates how burying wood can fight climate change

In 2013, Ning Zeng came upon an exceedingly old, and finally a really important, log.

He and his colleagues were digging a trench in the Canadian province of Quebec, one which they planned to fill with 35 metric tons of wood, cover with clay soil, and let sit for 9 years. The team hoped to indicate that the wood wouldn’t decompose, a proof-of-concept that burying biomass may okay be an inexpensive due to store climate-warming carbon. But all through excavation, they unearthed a pristine, twisted log that changed into very old, older than anything they'd possibly have possibly produced in their experiment.

“I actually remember standing there just it,” says Zeng, a climate scientist on the University of Maryland. He recalls thinking, “Wow, can we in actuality should continue our experiment? The evidence is already here, and better than we may do.”

That log changed into once a component of an Eastern red cedar that drew carbon dioxide from the air and transformed it into wood some 3,775 years ago, researchers report September 24 in Science. Buried beneath as little as two meters of clay soil for millennia, the log retained not not as much as ninety five % of that carbon, the learn about estimates.

“Scientists and entrepreneurs have long contemplated burying wood as a climate solution. This new work shows that that is a long way that you may be to take into accout,” says Daniel Sanchez, an environmental scientist on the University of California, Berkeley who wasn’t eager about the learn about. “High-durability, low-cost climate solutions like these hold immense promise for battling climate change.”

New solutions are sorely needed. Curbing greenhouse gas emissions isn’t enough to meet global climate targets, in keeping with the Intergovernmental Panel on Climate Change (SN:1/9/16). In the same way, about 10 gigatons of atmospheric carbon should be captured and stored every year by 2060. Plants store about 220 gigatons of carbon dioxide every year just by growing, but tons of this gets released back to the atmosphere through decomposition. Preventing only a fraction of that decomposition by burying wood may assist meet this goal. But that potential rests on finding conditions that may possibly prevent air, water and microbes from breaking down that carbon for long enough to make a difference.

Underground wood vaults

A schematic of a proposed wood vault show buried wood rests under a layer of clay soil that keeps oxygen from reaching the wood, helping it retain its carbon.

The ancient log gives researchers a clue. Zeng suspects the largely impermeable clay soil blanketing the region helped prevent oxygen from reaching the log, even at relatively shallow depths. “The kind of soil is relatively widespread. You just dig a hole some meters down, bury wood, and that is a long way in a position to be preserved,” he says.

Burying wood may cost as little as $30 to $a hundred dollars per ton of CO₂, the researchers estimate. That simplicity and cost, Zeng says, makes wood vaults more practical than developing direct air capture technology, which runs $a hundred to $300 per ton of CO2. If the conditions that preserved the Canadian log may okay be replicated — which remains unclear — buried biomass from discarded wood and sustainable harvesting may sequester as much as 10 gigatons of carbon every year, the researchers estimate.

Notwithstanding finding the conventional log, Zeng’s team carried out their planned experiment and are wrapping up the analysis now, partly to work out best practices. Nonetheless the log itself exemplifies wood vaulting’s promise, he says. “We have the evidence to claim ‘yes, it’s in a position to be implemented.’”