By
Quynh Nguyen

Redwood trees are the tallest living trees on earth. They grow fast and tall, which are good signs for the sustainability of their wood. However, redwood forests, especially the ancient ones, store a larger amount of carbon than any other forest type. So we had to ask: How sustainable is it to buy products made out of redwood?

Redwood is sustainable thanks to its carbon sequestration. The trees’ fast and easy regrowth allows their harvest without harming the forest, their extreme stability reduces CO₂ emissions in the manufacturing process, and emissions from transporting are considerably lower than for imported timber.

In this article, we’ll walk you through the life-cycle of redwood used for furniture and decking. Then, we evaluate its sustainability, potentials, and shortfalls. And in the end, we’ll show you tips for buying sustainable redwood. 

Here’s How Sustainable Redwood Is

Redwood is a sustainable material because of the coast redwood trees’ carbon sequestration and the carbon offset value at the end of any products made with redwood. 

“Sustainable: The ability to be maintained at a certain rate or level | Avoidance of the depletion of natural resources in order to maintain an ecological balance”

Oxford Dictionary

To better understand the sustainability of redwood, we assess the life-cycle of projects like flooring or furniture. This life-cycle assessment (LCA) is a method to evaluate the environmental impacts of each stage in a product’s life-cycle, from the making to the recycling. Over the years, companies have strategically used LCA to research and create more sustainable products. 

In this article, we’ll use the cradle-to-grave perspective of the LCA, examining the five stages of the life cycle of redwood. Where it is relevant, we also use data from cradle-to-gate assessments. 

The life-cycle stages of redwood	Each stage’s sustainability
Growing of redwood	Growing coast redwood trees for timber is sustainable thanks to the carbon sequestration potential and the speed and ease of regeneration.
Manufacturing of redwood	Redwood is exceptionally stable: it shrinks very little during drying and doesn’t have much seasonal movement. Sometimes, it is used without being dried first, which significantly reduces the carbon emission of manufacturing. Also, the wood waste in the process of turning redwood into furniture can be fully recycled, which further reduces the overall carbon footprint.
Transporting of redwood	Transporting is a relatively carbon-intensive stage in the life cycle of redwood furniture due to the emissions associated with operating the hauling vehicles that take timber to sawmills and factories, then furniture to stores. As redwood is a local timber from fast-growing softwood trees, the carbon emissions of transporting redwood products would be considerably lower than imported tropical timber.
Usage of redwood	Using redwood furniture can be sustainable thanks to the carbon capture during the products’ long life.
End-of-life of redwood	The end-of-life stage for redwood furniture is sustainable when the wood is reused or burned as bioenergy.

Overall, we can say that redwood is sustainable. However, the actual environmental impact of a particular product, like a gate or an outdoor table, depends on many factors, especially the distance and mode of transportation. Let’s dive deeper into each stage and find out how it can be more sustainable. 

How Sustainable Is the Growing Redwood

Growing coast redwood trees for timber is sustainable thanks to the carbon sequestration potential and the speed and ease of regeneration. 

What Type of Wood Is Redwood and What Does This Mean for Sustainability

Redwood comes from the softwood tree species Sequoia sempervirens, commonly known as Coast redwood or California redwood. These evergreen conifers have distinctive cinnamon-red bark, similar to the Giant sequoias. These two tree species have many common characteristics, including growing primarily in North America, but they are two different tree species. 

Coast redwood trees grow rapidly, adding an average of 3 feet in height each year. That is 1.5 to 3 times the annual growth rates of other softwood tree species like pine or Douglas fir. 

How Sustainably Does Redwood Grow

Coast redwood trees’ sustainability lies in the potential for carbon sequestration and their natural tendency for easy regeneration and restoration. 

• Carbon sequestration: As redwood trees grow, they absorb CO₂ from the atmosphere while releasing oxygen. They act as a carbon sink during their long lifespan. Coast redwood trees could reach 2,000 years old, with evidence reporting a redwood tree of 2,266 years.

As a carbon sink, Coast redwood trees pull a lot of greenhouse gasses out of the atmosphere, helping to mitigate the climate crisis. And they can store a lot as they grow up to 300 feet in height and 12 feet in trunk diameter. They are the tallest trees on earth, with the current record height set over 379 feet.

According to a Redwood and Climate Change Initiative study, old-growth ancient redwood forests store at least three times more carbon above ground than any other forest on earth. It comes down to their enormous size, century-long lifespan, and the carbon storage attribution of the redwood forests’ understory plants.

• Regeneration ease: Coast redwood trees have a natural tendency to regrow from sprouts. This ability is significant in reforesting ancient woodlands while replenishing the timber source.

Healthy redwood stumps sprout vigorously after a disturbance, such as a forest fire or harvest. On average, a dozen sprouts come out of a redwood stump within two years of disruption. They grow rapidly and form large trees and rebuild old forest structures in a short time, provided that proper thinning is in place.

Where Is Redwood Usually Grown

Coast redwood (or California redwood) trees grow exclusively in North America. These tree species tower the mixed forests of northern California coastal areas. Under the towering redwood trees are other trees like Douglas fir, big-leaf maple, tanoak, and a rich understory of shrubs, ferns, and fungi.

Harvesting redwood from natural forests, especially the ancient old-growth forests, can result in biodiversity loss regarding the tree species and wild animals that feed and shelter in those woods. 

One example is when loggers only cut down the biggest and tallest trees. That pattern would cause a reduction in the genetic diversity and quality of the trees within the stand, leading to gradual degradation of tree quality. 

Cutting down redwood trees also disrupts the forests’ wild animals, which depend on the forest for food and shelter. 

Many wildlife species live in the redwood forests, from amphibians like Pacific giant salamanders, red-bellied newts, and tailed frogs to mammals like bears, raccoons, bobcats, Pacific fishers, pine martens, black-tailed deer, and Roosevelt elk. 

A number of birds, including the endangered marbled murrelets, make nests in mature forest canopies. Streams passing through redwood forests often contain coho salmon, steelhead, and trout.

The bright yellow-orange banana slug and many other invertebrates are also found in this natural habitat. 

Illegal logging in the US is unfortunately not non-existent. The only way for consumers to tackle problems caused by illegal logging is to source sustainable woods. We will point you in the right direction with redwood at the end of this article. 

In total, logging of forestry products from plantations accounts for 26% of forest loss, which is a combination of deforestation and forest degradation. However, the loss in bio-diverse forests in tropical climates is more significant (and sometimes less properly recorded) than in temperate, well-managed logging forests. 

How Sustainable Is the Manufacturing of Redwood

Turning redwood into furniture has a relatively low carbon footprint because wood waste can be recycled fully. Wood chips, barks, and other residues during manufacturing and products at the end of their life can be turned into biomass pellets to offset the carbon emissions during harvesting and processing. 

The first step of manufacturing redwood furniture involves cutting down trees and turning them into lumber in a sawmill. The carbon emissions here come from electricity usage. It is easy to cut and saw redwood logs because the wood is relatively soft with a Janka hardness of 450 lb_f. In comparison, the Janka hardness of white oak and hard maple are 1350 lb_f and 1450 lb_f, respectively. 

The next step is to dry lumber. If a piece of lumber can be air-dried to the desired moisture content, no added energy is needed for this step. However, if a kiln is used, it requires extra energy, which could mean higher carbon emissions.

Redwood is exceptionally stable. It shrinks very little during drying and doesn’t have much seasonal movement. Thus, sometimes redwood is used in green-form (without being dried first) for decking projects. That significantly reduces the carbon emission of manufacturing. 

A cradle-to-gate assessment reports that kiln-drying 1m³ of redwood lumber results in 33 kg CO₂-eq, almost 1.5 times higher than the total carbon emission of all other stages (forest management, harvesting, transporting to the mill, and sawing). 

Burning wood waste (biomass) can, however, generate electricity for running a kiln. In the above assessment, the carbon credit from using biomass electricity is actually higher than the carbon emission of all cradle-to-gate stages put together. 

At least 90% of all thermal energy used for kiln drying in the US hardwood sector is derived from biomass (instead of fossil fuels). 

Sometimes, redwood lumber is planed on all four sides. This planning process also adds some CO₂ emission, though not as much as the drying process. 

How Sustainable Is the Transportation of Redwood

Transporting is a relatively carbon-intensive stage in the life cycle of redwood furniture due to the emissions associated with operating the hauling vehicles that take timber to sawmills and factories, then furniture to stores. 

As redwood is a local timber from fast-growing softwood trees, the carbon emissions of transporting redwood products would be considerably lower than imported tropical timber, like ipe or teak. 

The actual emission during this stage depends on the type of vehicles used, the fuel they need, and the distance the wood travels. Calculations made by the Norwegian Forest and Landscape Institute showed that smaller wood hauling trucks emitted more CO₂ per transported cubic meters of timber: 1.25 times more than larger wood hauling trucks, 1.3 times more than sea vessels, and six times more than freight trains. Therefore, the sustainable transportation option would be rail or large trucks running on biofuel. You can check with your wood suppliers how their products are transported and opt for the best option. 

How Sustainable Is the Usage of Redwood

Using redwood furniture can be sustainable thanks to the carbon capture during the products’ long life. 

Coast redwood is rated as moderately durable to very durable regarding decay resistance. This timber is also naturally resistant to insects, fungi, and fire as they are high in tannin and do not produce resin or pitch. A redwood decking, for example, could last for two to three decades. 

When redwood is decayed, either naturally in the forest or because of damage caused by usage at home, the carbon stored in the wood is released back to the atmosphere. Therefore, long-lasting furniture can be considered a good way of keeping carbon out of the atmosphere. If the wood is then reclaimed for making another piece of furniture, its positive carbon storage environmental impact is even higher. 

How Sustainable Is the End-of-Life of Redwood

The end-of-life stage for redwood furniture is sustainable when the wood is reused or burned as bioenergy. 

There are a few scenarios for wood products – outdoor furniture, decking or fences- at the end of their life: 

1. They can end up in landfills and don’t decompose. In this case, it keeps its role as carbon storage.
   
2. Wood products can also be upcycled and reused, extending their role as carbon storage. New wood products often travel much further to their markets, compared with recovered wood products. The latter is typically made in urban centers and sold locally, which lowers the transportation environmental burdens.
   
3. In another end-of-life scenario, products like a tulip cabinet can be burned for biomass energy displacing coal or natural gas in generating electricity.
   

With smaller household items, like a doorknob or a small chair, the offset won’t be as high as there is much less waste for burning. However, if such products are made from manufacturing wood waste as by-products, their carbon footprint is minimal. 

In a cradle-to-grave assessment, the overall results show a negative carbon footprint for redwood lumber production. Specifically, redwood decking stores three to five times more greenhouse gas emissions than the amount released in all stages, from growing and harvesting to manufacturing, transporting, usage, and end-of-life disposal. 

How Can You Buy Redwood More Sustainably

The key to sustainably buying any wood is to check on relevant environmental and original certifications. Reliable certifications for sustainable woods are: 

• Forest Stewardship Council: 

An FSC certification ensures that the redwood comes from responsibly managed forests that provide environmental, social, and economic benefits.

• Program for Endorsement of Forest Certification: 

PEFC’s approaches to sustainable forest management are in line with protecting the forests globally and locally and making the certificate work for everyone. Getting a PEFC certification is strict enough to ensure the sustainable management of a forest is socially just, ecologically sound, and economically viable but attainable not only by big but small forest owners. 

Why Is It Important to Buy More Sustainable Wood

Buying sustainable wood also means helping to prevent illegal or unsustainable logging, which harms the forests’ biosystems and accelerates climate change. 

Logging of forestry products from plantations accounts for 26% of forest loss. Cutting down trees for wood has a lesser impact on carbon storage than digging up the whole forest floor and turning it into farms or mines. However, if logging is not sustainably managed, it can badly damage wildlife.

When logging happens in tropical forests – the bio hotspots of our planet – the biodiversity loss can be much more damaging. Subtropical and tropical forests are packed with unique wildlife – endemic mammals, birds, and amphibians. The displacement of such wildlife during poorly managed logging would be a major contributor to global biodiversity loss. 

Sustainable management of forests also means that trees are cut down for timber only when they are mature. These trees will then be able to regrow and eventually replace the loss of canopy, absorb carbon from the atmosphere and reduce the effect of climate change. 

Final Thoughts

You can buy sustainable furniture and decking made from redwood as long as the timber comes from sustainably managed forests. And, to make it even more sustainable, use any redwood furniture for as long as you can, upcycle the material to extend its usage, and arrange for it to be recycled fully.

Stay impactful,

Sources

• Science Direct: Life-cycle assessment (LCA)
• MIT SMR: Strategic Sustainability Uses of Life-Cycle Analysis
• European Environment Agency: cradle-to-grave
• Science Direct: Cradle-to-Gate Assessment
• Conifers: Sequoia sempervirens
• Britannica: giant sequoia
• California Department of Parks and Recreation: About Coast Redwoods
• Impactful Ninja: How Sustainable Is Pine Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Douglas Fir Wood? Here Are the Facts
• LIVE SCIENCE: Giant Sequoias and Redwoods: The Largest and Tallest Trees
• THE WOOD DATABASE: COAST REDWOOD
• Save The Redwoods: Redwood and Climate Change Initiative
• MDPI: Regeneration Dynamics of Coast Redwood, a Sprouting Conifer Species: A Review with Implications for Management and Restoration 
• Impactful Ninja: How Sustainable Is White Oak Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Maple Wood? Here Are the Facts
• Forest Service: Life-cycle assessment of redwood lumber products in the US 
• American Hardwood: Environmental Life Cycle Assessment
• Impactful Ninja: What Is the Carbon Footprint of Biomass Energy? A Life-Cycle Assessment
• Impactful Ninja: How Sustainable Is Ipe Wood? Here Are the Facts
• Impactful Ninja: How Sustainable Is Teak Wood? Here Are the Facts
• Science Norway: Larger logging trucks give less CO₂ emissions
• Forest Stewardship Council
• Program for Endorsement of Forest Certification
• Our World in Data: Epidemic Mammal Species