By now, it’s a well-known fact: The built environment and the concrete industry account for some 40 per cent of global greenhouse gas emissions. Yet, while the urgency of re-thinking our buildings is obvious, transforming global practices is no simple feat. While a welcome and much-touted transition towards mass timber design is gradually gaining ground, myriad challenges persist. What kinds of building typologies and wood technologies are best suited to support social and environmental sustainability? How do global supply chains impact the carbon costs of mass timber? What kind of forest management techniques should we adopt? These are just some of the questions at the heart of Lindsey Wikstrom’s landmark new book — excerpted below — Designing the Forest and Other Mass Timber Futures.

A founding partner of New York-based architecture practice Mattaforma, Wikstrom will also lead a workshop at this year’s inaugural AZURE Human/Nature Conference, taking place in downtown Toronto on October 24-25. Tickets are available now!

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In 1923, the first patent outlining a concept for gluing small pieces of softwood together was filed in Tacoma, Washington. To make composite lumber was “to produce a new article of manufacture suitable for many commercial purposes in which the original wood could not be used, and in which its properties render it superior to other existing substances.” Adhering wood together makes mass timber much stronger than traditional forms of wood that are cut directly from logs, like dimensional lumber or heavy timber. Over the last 100 years, mass timber has been gradually promoted. Since the 1990s, it has grown into the face of environmentally sensitive architecture. Because it can replace some of the most destructive and ubiquitous materials on earth, mass timber promises to reduce the carbon footprint of cities. But, at the same time, it introduces a whole host of unique challenges. If mass timber is to be a new way to fight climate change, these challenges have to be more carefully considered. Mass timber has the potential to be non-extractive, but is not inevitably so.

No matter the material, all buildings have both destructive and restorative effects. Construction always demands extracting, moving, and transforming matter from one place to another. Typically this movement deteriorates the environment of one place and improves quality of life in another.

To erect a building’s primary structure from mineral-based materials like concrete and steel, geological formations are pulverized into dust, liquified, and re-formed into environments for human occupation. This way of building has benefited some of humanity in the short term, but it cannot continue if extinction is to be avoided. Geological formations don’t readily renew themselves. Minerals, which form over millions of years, exist in finite quantities. They are dead and durable, characteristics that make them easy to build with. They don’t respond to the changing seasons. They don’t decompose. They can be ground down and poured into silos and trucks. They can be stored indefinitely. Minerals are excavated from rock beds underneath places that are full of life. Concrete’s component parts — sand, lime, silica, alumina, magnesia, sulfur trioxide, alkaline, iron oxide, and calcium sulfate — are all mined in different locations around the world, the effects of which fundamentally transform ecosystems. Once brought together, the ingredients are cooked at high temperatures into a slurry called clinker, a process that requires immense amounts of energy to complete. This energy requires fuel, which, when burned, emits CO2 and other greenhouse gases into the atmosphere. The greenhouse gas (GHG) emissions from industrial heat — the fuel combustion needed to manufacture materials like concrete and steel — amount to twice the global emissions from cars.

Plant-based materials like mass timber share some similarities with mineral-based materials: they both cause animal and plant habitat to be turned into human habitat. Extraction of either can cause harm. Mass timber risks deforestation, if trees are not replanted, or damage, if a transplanted species disrupts an ecosystem. But this is where the similarities seem to end. Trees introduce a whole host of complexities and opportunities that minerals don’t have. They are alive. They take time to grow, and grow in surprising ways. Trees respond to weather and seasons and catastrophic events. They decompose. Some trees are sensitive, others tough. Trees have been found to cultivate social ties among themselves. Some forests have the legal status of persons. They have a metabolism. Trees can reproduce indefinitely. After they are harvested from the earth, they have to be commodified into standardized shapes, sizes, and grades to enable their movement across the globe. Standards like that of dimensional lumber attempt to account for and incentivize levels of predictability in the material’s chemical condition as well as its availability, which is generated by the human effort of extracting, transporting, and manufacturing.

Between May 2020 and May 2021, during the first year of the Covid-19 pandemic, the price of lumber futures quintupled. Consumers were shocked. Lives were in danger across the supply chain and its participatory landscapes, and the risk was reflected in wood’s high price. Most of the time, global commodification successfully disguises the effort required to source a material and the risks taken to bring it into a standardized form. But in times of crisis, these difficulties become more visible. For a moment, consumers were asked to pay more ‘here’ for damage ‘elsewhere.’ In a global economy, lower prices tend to reflect higher levels of damage, as a result of fewer protections for either the environment or workers.

Reciprocally, higher prices typically imply more protections. Subsidizing environmental and human damage through this type of economy is how global warming has been perpetuated by every consumer. The pandemic economy was an example of how material prices could reflect more widespread protections for the environment and for workers. The United Nations’ Intergovernmental Panel on Climate Change (IPCC), founded in 1988, is the international body responsible today for understanding how economy, ecology, and policy have either destructive or restorative planetary effects. Every six or seven years, the IPCC publishes an analysis of human-induced climate change. In April 2022, two years into the pandemic, the IPCC released their Sixth Assessment. They issued similar warnings as previous publications, but raised the stakes by reporting that, with the currently implemented policies, it won’t be possible to stay below 1.5˚C of warming.

In his book The Uninhabitable Earth: Life After Warming, David Wallace-Wells brings together scientific reports looking at rising sea levels, the increasing number of devastating forest fires, and at-risk food infrastructure to present a holistic view of possible futures with each degree of warming. Two degrees of warming means the complete collapse of the planet’s ice sheets, putting Miami, Dhaka, Shanghai, and Hong Kong underwater before the year 2100. Four-hundred-million people without fresh water. Major cities at the equator will be unlivable, with 32 times as many heat waves in India as there were in 2019, that would last five times as long and expose 93 times more people to heat death. At three degrees, Europe would be in a permanent state of drought. Areas burned by wildfire would double in the Mediterranean and increase sixfold in the United States (from seven million acres in 2021 to 42 million acres). At four degrees, there would be eight million more cases of dengue fever in Latin America alone, a global food shortage, and nine per cent more heat-related deaths. Damage from flooding would increase 30-fold in Bangladesh, 20-fold in India, and 60-fold in the UK. Climate damages could easily surpass $600 trillion, more than twice the wealth that exists today. These changes could happen within our lifetimes, putting the next few decades in the spotlight in the context of our species’ history.

According to the IPCC, “deep, rapid and sustained” change is required. With this in mind, construction should be happening less, and in less wasteful ways. But the United Nations predicts that the amount of construction will continue to expand at unprecedented rates. With population growth and increasing needs for infrastructure and improved living environments around the world, it is estimated that the equivalent of a New York City’s worth of buildings, or five billion square feet, will be built every month for the next 40 years. The materiality of, and energy use within, the built environment contributes around half of the global greenhouse gas emissions on the planet. Materials used to build cities come from landscapes, so both territories are in need of redesign.

One way to effect this change is to build with mass timber. Using materials that don’t decompose or have social ties may seem far simpler than dealing with the vagaries of wood, but in the long run our dependence on nonrenewable resources is what is cooking our planet.

Until mass timber, it would have been strange to compare wood and concrete. These materials have been honed separately over time, used in distinctly different applications. Concrete and dimensional lumber have been optimized through the pressures of building codes, economies of scale, construction efficiencies, and regional knowledge, but also the perceived aesthetic of modern life. Wood framing made single-family houses accessible, while concrete and steel skyscrapers enabled massive urbanization around the world. This has led to the perception that urban density, a form of human occupation that reduces CO2 emissions per capita through the pooling of resources like mass transit, is only possible with concrete and steel. But when cities are made with high–embodied energy materials, they actively work against this goal. Mass timber transforms wood, once a material for low-density environments, into one suited for urban life. Mass timber is the first plant-based structural material that can replace some of the most polluting materials that support dense environments. And mass timber can be regenerated within our lifetimes.

Fears that cutting trees will reduce the amount of CO2 captured from the atmosphere at a time when that is essential are not unfounded, but misguided; meanwhile, pouring concrete when mass timber could be used continues to cook the planet. Simply put, trees usually grow back, and when replanted, young trees also absorb CO2. But ensuring the quality of a forest over time is a much more challenging issue. Are there enough trees in the world to support cities made of mass timber in the future? Can there be? It is possible to design forests to remain biodiverse, provide habitat, and capture and store CO2 inside mass timber buildings, but achieving this takes effort, expertise, coordination, and technology. This is why measuring activities in the forest and in urban environments as one carbon cycle is essential.

If mass timber is not adopted, and concrete continues to be poured, unnecessary emissions are generated for forests to absorb. If mass timber is embraced, the forest will have less emissions to absorb, with an increased number of younger trees to do the work. Throughout history, professional foresters and ecologists have shaped and interpreted forests, designing them in ways that balance habitat, timber, and resilience (or for less noble motives), but we’ve never before lived in towering cities made of organic material. This requires new levels of collaboration. It’s easier to presume mass timber is too risky. But when the IPCC reports that in order to have a 50 per cent chance of keeping global warming to 1.5˚C by century’s end, global CO2 emissions must halve in a decade, reach net zero in the 2050s, and go net-negative thereafter, continuing with life as usual is extremely problematic. There is an opportunity and an urgency to completely rewrite the way urban environments are made.

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Architect Lindsey Wikstrom is the founding partner of Mattaforma. Her forward-thinking work weaves together ideas of care, ecosystems and the positive influence that design can have in society. At the AZURE Human/Nature Conference, Wikstrom will lead the workshop Mass Timber – Care Is Choreography with Mattaforma.

More information about the Human/Nature conference – including a full overview of keynotes, panels, workshops, and speakers — is now available on our dedicated website. Tickets are on sale here!