Building structures out of wood doesn’t seem like a particularly innovative idea—people have been building wood houses for centuries. But when it comes to new efforts to be sustainable, all-timber construction is the latest advancement. How exactly is a process that requires us to cut down trees more environmentally friendly, though? Sustainable forest management would be crucial, experts say, but if that is part of a global boom in using timber in new constructions, new wood buildings could store up to 700 million tons of carbon a year.

In a paper published in the journal Nature Sustainability on January 27, experts at the Potsdam Institute for Climate Impact Research in Germany dig into the potential for timber buildings to act as carbon sinks. Natural carbon sinks, like forests, absorb and capture carbon dioxide from our atmosphere. Timber buildings, the researchers say, could be crucial carbon sinks as the world’s population, and thus urban construction, increases in the coming years.

Experts have predicted that by 2050, there could be more than 9.5 billion people on Earth, and that 70% of that population will live in urban environments. That means demand for new housing and commercial buildings will grow as well, Galina Churkina, lead author of the Potsdam study, notes in a statement, and the production of cement and steel will continue to be a major source of greenhouse gasses, unless we change the way we build.

Currently, cement is the source of 8% of global CO2 emissions; more than jet fuel, which accounted for 2.4% of global CO2 emissions in 2018. If we continue to build with concrete and steel, researchers say, the cumulative emissions from these mineral-based construction materials might account for one-fifth of the global CO2 emissions budget up to 2050—a budget, they stress, we can’t exceed if we want to keep warming below two degrees.

To reach net-zero carbon emissions by midcentury, we need to lower our carbon output and also create carbon sinks to balance the atmosphere and counteract emissions that may be impossible to avoid. “Buildings, which are designed to stay for decades,” researchers write in the paper, “are an overlooked opportunity for a long-term storage of carbon, because most-widely used construction materials such as steel and concrete hardly store any carbon.” The opportunity then lies in timber buildings—mass timber specifically, which refers to the use of large, solid engineered wood panels, often made of smaller boards layered and laminated together, to construct walls, floors, and roofs (and differs from thinner light frame or post-and-beam construction). A five-story residential building made with laminated timber can store up to 180 kilos (nearly 400 pounds) of carbon per square meter—three times more than natural forests with high carbon density.

In their study, Churkina and her team looked at four scenarios of mass timber construction over the next 30 years: “business as usual,” in which the majority of new buildings are made with concrete and steel and just 0.5% are made with wood; a 10% timber building scenario; a 50% timber building scenario; and a scenario in which 90% of new construction is made with wood, which would require countries that currently have lower levels of industrialization to also make the switch. All these options would sink carbon, but the more mass timber buildings, the more carbon sequestered: The lowest scenario could result in 10 million tons of carbon stored per year, the researchers say, and in the highest, nearly 700 million tons.

These environmental benefits are contingent, though, on where all this timber is sourced, and what happens to the wood at the end of a timber building’s life. “Protecting forests from unsustainable logging and a wide range of other threats is thus key if timber use was to be substantially increased,” coauthor Christopher Reyer says in a statement. The demand for all these mass timber buildings could be met by harvesting both softwood and hardwood tree species as well as bamboo, and by generally harvesting more timber than we currently do. When it comes to the end of these wood buildings’ lives, it’s crucial to design timber buildings “so that their components can be reused or recycled,” the researchers write, and also encourage the collection of timber from demolished building so it could be recovered and reused.