Are Carbon Offsets Effective?
I love trees. Not for nothing am I called, on occasion, a tree hugger. But I got to wondering recently about the popular belief that planting trees will help save the environment; does planting urban trees really help? What about carbon offsets offered by many companies that offer to plant them elsewhere? I decided to do a little fact checking to find out more, because while I love trees, I don’t love futile gestures!
First off, the claim: trees are good for the environment because they act as carbon sinks, utilizing carbon dioxide in their biochemical processes and releasing oxygen in exchange. In addition, they help to stabilize ambient temperatures, acting like thermostats to prevent wild temperature swings. As if that wasn’t enough, trees can help retain topsoil with their tough root balls, and they offer habitat for both plants and animals that can’t thrive in exposed environments.
So far, so good, right? But how does it break down when you start talking about tree-planting initiatives? For starters, are the trees being planted suitable to the environment? If trees won’t thrive, require lots of water, or won’t reach their full potential, they aren’t good choices for planting — in a home garden, as part of an urban greenification movement, or in a larger-scale tree-planting project. Furthermore, are they being planted in groups, or in isolated islands? Trees do the most benefit when they grow in stands, clusters, and forests, where they offer contiguous habitat and create meaningful heat sinks.
That’s why Central Park is great for New York City’s environment, but a single tree growing in Brooklyn, well, honestly doesn’t do that much. (Even if it’s a very nice tree.)
Many of the trees being planted today are fast-growing, which on the surface is good news. It means they absorb carbon quickly and will continue to do so for up to 50 years, until they reach maturity. However, they aren’t as good as preserving original forests. Why? Because original forests are their own complex ecosystems, with trees of varying ages and stages of development in addition to complex, diverse life forms relying on them for sustenance and a place to live. The best bang for your buck in terms of carbon reduction and helping the Earth is definitely a contribution to efforts to preserve existing forests.
There are also issues like sourcing young trees, buying land, and managing pests, drought, disease, and other problems. When you pay for a tree as part of a carbon offset, are you positive that tree will make it to adulthood or be replaced if it dies? If you aren’t, your well-meant effort may not make a big difference for the environment.
Researchers have also taken a look at where planted trees do the most good, and they’ve found that tropical forests are our friends, but those at more extreme latitudes may not be. Research suggests trees in the tropics do the most good in terms of controlling temperatures and CO2 levels — and, of course, tropical forests are also under extreme pressure thanks to demands on land usage across the world’s tropical reasons. Protecting existing forests in these areas should be a priority, followed by reforestation with appropriate tree species.
Bottom line? Plant a tree if you love trees and want one in the garden, but if you want to support the environment, put tropical conservation first, followed by reforestation in that region. While you’re at it, make sure the organization(s) you support uses third party certification and other accountability measures so you can be assured your money is being well spent. Furthermore, confirm that your carpenter is using sustainable wood.