‘Not a valid assumption’: Climate policy overestimates shift to alternate materials

When a homeowner is faced with a lumber shortage, a common assumption in climate policy is that they may switch to steel or plastic to build their fence.

Not surprisingly, a team of researchers has found that reality is way more complicated.

“The homeowner could become more efficient or find a different supplier rather than substitute the wood with other materials,” explains Dr. Caren Dymond, BSc’94, MSc’98, PhD, an adjunct professor with the Department of Biological Sciences in the University of Calgary’s Faculty of Science.

“The decision also avoids an increase in carbon pollution. Wood products are typically less emission intensive than steel or plastic.”

New research by Dymond; PhD student Adam Robertson in UCalgary’s School of Architecture, Planning and Landscape; and independent researcher Doug Hopwood applied the homeowner example on a much bigger scale: the U.S. softwood lumber market.

The research, published online last month in Global Environmental Change Advances, found real-world substitution is about 90 per cent lower than assumed.

It comes as the world gets together to agree on actions to address the climate crisis at COP31, the United Nations Climate Change Conference in Antalya, Türkiye.

Evidence shows that climate change is claiming lives, harming health and damaging people’s livelihoods due to more frequent and severe wildfires, droughts and floods.

Plans to mitigate extreme events are typically based on expected changes in product use.

“A lot of people make climate change mitigation decisions and investments based on the theory that if we change the supply of products, it'll have a big outcome,” says Dymond. “We found that’s likely not a valid assumption.”

The researchers studied the softwood lumber market from 1988 to 1998 during a major supply shock caused by reduced harvesting on public lands to protect wildlife.

They found an 8.5-per cent substitution rate, rather than 100 per cent.

“Efficiency was an important way people filled the gap,” says Dymond. “People in forestry, construction and manufacturing became much better about using logs that were available.”

The other change, she noted, was that the harvest shifted geographically.

“There was more wood coming into the country, such as from British Columbia, and there was more harvesting on private lands,” Dymond says.

The new research suggests investments intended to mitigate extreme weather events may not achieve needed carbon pollution reductions. Therefore, Dymond says, decisions based on the 100-per-cent assumption should be re-examined.

She notes that these findings stem from only one case study, so can’t be generalized, but they are consistent with other papers across many sectors of the economy.

“Based on my 20-plus years of research, I would say that we need a portfolio of solutions to climate change,” Dymond says. “Forest conservation can be part of that portfolio. 

“I would be cautious about increasing harvest as proposed in some Climate Smart Forestry programs unless you know how buyers and businesses will respond.”