Don’t invest your carbon offset in trees

Trees are bad carbon credits

Trees are climate change miracles.

They take in carbon and give up oxygen. The region around them benefits from their shade and trees put moisture into the air. A mature tree can absorb 20 to 30 kilograms of carbon annually.

However, trees make lousy carbon credits.

Let’s begin with age. A tree starts as a seedling, a tiny plant. That seedling captures almost no carbon. It takes 10 years (depending on the species) for a tree to become a carbon-absorbing machine. When you invest in a tree-related carbon credit, you are essentially saying “I will emit carbon today but I promise to make up for it 10 years from now”.

A song by Malvina Reynolds goes: “And if you think you'll love me for a long, long time, plant an apple tree.”

The very length of trees’ lives make it hard to safeguard them. You can plant a tree today but who is going to safeguard it over the next 100 years? Trees can be lost to forest fire (releasing all the carbon they absorb). They can be lost to development and they can be lost due to disease, such as the pine bark beetle.

We also aren’t very good at creating healthy ecosystems. Planting projects have chosen trees that are wrong for the region, which then became an invasive species.

The Fort McMurray fire in 2016 was made worse because planted trees lowered the water table, drying out the peat bog, making the peat highly flammable. The effort to replace hardwoods with sustainable bamboo has resulted in forest loss (ironically hardwood forests are cut down to plant bamboo), and ecosystem loss from monoculture (planting nothing but bamboo). We’ve certainly learned from these mistakes but they highlight how hard it is to get it right.

One of the biggest issues with tree planting is the tug of war between food crops and tree plantations. In Brazil, which contains 60% of the Amazonian rain forest, trees are cut down to create land for agriculture and areas for grazing livestock.

Before we shake a finger, we need to acknowledge the settlers aren’t getting filthy rich destroying the rainforest, they are fighting for survival. In other regions, replanting projects have purchased agricultural land outright in countries with uncertain food production. In some cases Indigenous roles in determining land use have been trampled in the interests of replanting.

However, planting trees is not a worthless endeavour. While they aren’t a high-quality carbon offset, they can play an important role in climate adaptation. The climate is getting hotter and unusual weather patterns, such as heat domes, are bad around the world.

The 2021 B.C. summer heat dome was responsible for between 600 to 700 deaths. These high temperatures are bad across Canada but worse in the cities. Because cities are primarily made of concrete and asphalt, they trap heat. Planting trees (“urban greening”) can go a long way towards mitigating heatwaves.

On a super-local scale, if you own your house you might take a look at your southern exposure. Would your house benefit from a shade tree? If you pick a deciduous tree you can have it both ways—in the summer the leaves will produce shade and in the winter you will still get the light and heat from sunny days. A pergola on the south face can be designed to let in winter light and limit summer heat.

Tree planting is less powerful globally. Rich countries plant more trees in developing countries than they do locally.

Support urban forestry in your location. And, if you are in the market for carbon offsets, look for projects that are measurable and permanent.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

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About the Author

Kristy Dyer has worked in the sustainability field for more than 10 years, including work with solar energy in New Mexico and cleantech in Silicon Valley. After she moved to the Okanagan, she ran a small business, Teaspoon Energy, doing energy audits of large houses. Most recently, she worked for a B.C. business doing carbon footprints for tourism organizations.

She has written about sustainability since 2012. You can find her columns archived at TeaspoonEnergy.blogspot.com.

Dyer has a background in physics and astronomy, and has occasionally been caught trying to impersonate an engineer.

A long-time member of First Things First, Penticton’s local climate change group, whose goals are to educate and lobby for solutions to the climate crisis, Dyer is honoured to live, work and play in the unceded, ancestral and traditional territory of the Syilx Okanagan Nation.

You can contact her at [email protected]

The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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