Logging extensive areas of boreal forests and submerging the trees in the Arctic Ocean could potentially eliminate up to 1 billion tons of carbon dioxide from the atmosphere each year.

Researchers suggest cutting down wildfire-prone coniferous trees and transporting them through six major Arctic rivers, including the Yukon and Mackenzie, where they can sink within a year.

“Currently, we have forests that sequester significant carbon, but the next challenge is finding ways to store it without burning,” says Wolf Bungen from Cambridge University.

To combat carbon emissions from hard-to-electrify industries, it’s essential to explore methods for atmospheric carbon reduction. While direct air capture technology is costly, tree planting can backfire if the trees end up dying or burning.

Several companies are working on wood burial techniques. For instance, a U.S. initiative, Running Tide, sunk 25,000 tonnes of wood chips off Iceland’s coast but faced shutdown due to environmental concerns.

Approximately 1 trillion tonnes of carbon are stored within the wood, soil, and peat of boreal forests across North Eurasia and North America, a figure expected to rise as climate change accelerates plant growth. However, with increasing wildfire frequency, this carbon could be released.

Bungen and his team previously discovered that wood can survive for up to 8,000 years in cold, oxygen-limited Alpine lakes without decomposing or emitting CO2. Six Arctic rivers transport substantial amounts of logs, with driftwood in deltas estimated to contain over 20 million tons of carbon. Carl Stadie from Germany’s Alfred Wegener Institute was not part of the study.

If every year, 30,000 square kilometers were cleared along each river, placing the wood on river ice in winter and then replanting, it could absorb up to 1 billion tons of CO2 annually, researchers estimate.

However, some US rivers continue to experience biodiversity loss a century after timber removal, warns Ellen Wall of Colorado State University.

“Dumping a massive amount of logs into a river resembles pushing brush into a river,” she notes.

Moreover, if wood becomes lodged on beaches or in tributaries, causing flooding, it could thaw permafrost and increase methane emissions from microorganisms.

“We could see a scenario where the wood aids ocean carbon sequestration, while onshore flooding and melting snow cause carbon release at high altitudes,” warns Merritt Turetsky from the University of Colorado Boulder.

Inadequate cold or oxygen-free conditions may lead to wood decomposition rather than sinking. Driftwood frozen in sea ice is often transported to the Faroe Islands.

“In a worst-case scenario, vast forest areas could be cleared, impacting the carbon they store,” says Stadie.

Roman Dial, a professor at Alaska Pacific University, warns that this proposal may be exploited by commercial logging and could face criticism from all sides of the political spectrum.

“How extensive is the list of potential unintended consequences that could unfold in the Arctic, given our limited understanding?” he questions.

Some regions of the Arctic ocean floor might not be suitable for conservation, according to Morgan Raven at the University of California, Santa Barbara. However, others could benefit from exploration, given the substantial influx of wood into the Arctic and other oceans. The Earth once experienced a greenhouse climate era 56 million years ago.

“We can investigate sediments and rocks to understand how this experiment was conducted in the past,” Raven concludes.