Researchers propose felling coniferous trees from boreal forests prone to wildfires and sinking them via Arctic rivers to sequester up to 1 billion tonnes of carbon dioxide annually. This method aims to store carbon long-term in ocean depths, drawing on evidence of preserved wood in cold environments. However, experts warn of potential ecological risks, including biodiversity loss and permafrost thaw.
The boreal forest, spanning northern Eurasia and North America, stores up to 1 trillion tonnes of carbon in wood, soils, and peat. As global warming boosts plant growth, it also intensifies wildfires, releasing this carbon back into the atmosphere. To counter this, a team led by Ulf Büntgen at the University of Cambridge suggests selectively logging 30,000 square kilometres along each of six major Arctic rivers—such as the Yukon and Mackenzie—annually, ideally in winter when ice allows piling timber for transport. The trees would sink in the ocean within about a year, preventing decay and CO2 release.
Büntgen's prior research shows wood can remain intact without rotting for 8,000 years in cold, low-oxygen Alpine lakes, supporting the idea's feasibility. Replanting logged areas could then absorb another 1 billion tonnes of CO2 yearly through regrowth. Natural driftwood in river deltas already holds over 20 million tonnes of carbon, per estimates from Carl Stadie at the Alfred Wegener Institute.
Yet, the plan faces criticism for its environmental toll. Ellen Wohl at Colorado State University notes that historical timber floating in US rivers still harms biodiversity a century later. "You run a giant mass of logs through, and it’s like you’re ramming a scouring brush down the river," she says. Merritt Turetsky at the University of Colorado Boulder warns that log-induced flooding might thaw permafrost, spurring methane emissions from microbes. "We could see a situation in which the wood itself promotes marine sequestration, but flooding or thaw on land promotes upland carbon release," Turetsky adds.
Additional concerns include incomplete sinking, with driftwood potentially traveling far or decomposing in warmer waters. Stadie cautions, "In the worst case, you have just deforested tremendous areas of forest… that stores carbon on its own." Roman Dial at Alaska Pacific University fears commercial exploitation and political backlash, asking, "And how long is the list of possible, unavoidable and potentially nasty unintended consequences in the Arctic, a place we hardly understand even now?"
Morgan Raven at the University of California, Santa Barbara, sees promise in some seafloor areas for preservation, citing geological evidence from 56 million years ago when wood influx may have cooled Earth. "We can go and look in the sediments and in the rocks and in Earth’s history for examples of how this experiment has run in the past," she says. The proposal appears in NPJ Climate Action (DOI: 10.1038/s44168-025-00327-1).