Is Planting Trees to Offset Carbon a Good Strategy?

In the coming years, thousands of companies, governments, individuals and NGOs will boast about planting trees to offset carbon dioxide. Governments have pledged to restore forests the size of South Africa. Startup companies are looking at cheaper ways to plant new trees. Some are restoring forests on behalf of people.¹ Even oil companies are buying forests.²

But, is all this tree planting a good strategy for the environment? Will it stop our planet heating up? Let’s explore some of these questions and areas.

How much carbon do trees absorb?

Trees absorb carbon dioxide and water, and they turn it into oxygen and organic compounds using sunlight. We call this process photosynthesis.³ But calculating how much carbon a tree absorbs varies depending on its species, location, and weather conditions. Each tree in a tropical forest absorbs around 50 pounds of carbon dioxide annually, according to some scientists.⁴ A maple tree can absorb approximately 400 pounds of carbon dioxide over 25 years, which is approximately 16 pounds per year.⁵

Older trees are also estimated to absorb more carbon than younger trees. This is because they need more organic material to build and sustain themselves.⁶

What role do trees play in the carbon cycle and in controlling the level of greenhouse gases?

Trees play an outsized role in regulating the Earth’s temperature. They are among the most natural mechanisms we have to recycle carbon dioxide back into oxygen.⁷ Greenhouse gases, such as carbon dioxide, raise global temperatures because they trap heat inside them. The more CO2 in the air, the more heat that gets trapped and temperatures rise. In turn, that destabilizes weather patterns all over the world.⁸

Between 2001 and 2019, the world’s forests absorbed over 15 billion tonnes of CO2 every year, according to NASA research.⁹

Moreover, trees also enrich and hold on to the soil around them. This also absorbs carbon from the atmosphere. In other words, trees are vital to controlling the level of greenhouse gases in the atmosphere.¹⁰

What happens to carbon in trees when they die?

When a tree dies naturally, its wood and leaves start to decompose as microbes, bacteria and fungi start feeding on it. Over time, that process leads to the stored carbon being released back into the atmosphere. This process can take decades.¹¹

Moreover, a tree also feeds organic material into the soil underneath. If a tree dies, the bacteria and microbes in the soil below lose their source of nutrients, which depletes their numbers. In other words, when a tree dies, the surrounding wood and soil start to emit carbon back into the atmosphere.¹²

Overall, while companies should be commended for planting more trees, this cannot substitute for offsetting carbon emissions. Trees are only a temporary solution for storing and offsetting carbon. We still need to reduce our emissions to prevent climate change.¹³

1. Peters, A. (2018). Planting Trees To Save The Planet Is Turning Into Big Business. [online] Fast Company. Available at: https://www.fastcompany.com/40517287/planting-trees-to-save-the-planet-is-turning-into-big-business.
2. Nasralla, S. (2020). Big carbon? Oil majors turn to nature to help plug the revenue gap. Reuters. [online] 8 Dec. Available at: https://www.reuters.com/article/us-climate-change-oil-carboncredits-focu-idUSKBN28I0HM.
3. Bassham, J.A. and Lambers, H. (2019). photosynthesis | Importance, Process, & Reactions. In: Encyclopædia Britannica. [online] Available at: https://www.britannica.com/science/photosynthesis.
4. University of New Mexico. (n.d.). How to calculate the amount of CO2 sequestered in a tree per year. [online] Available at: https://www.unm.edu/~jbrink/365/Documents/Calculating_tree_carbon.pdf.
5. Sierra Club. (2018). How much carbon do trees really store? [online] Available at: https://www.sierraclub.org/sierra/2016-2-march-april/ask-mr-green/how-much-carbon-do-trees-really-store.
6. Erickson-Davis, M. (2019). Tall and old or dense and young: Which kind of forest is better for the climate? [online] Mongabay Environmental News. Available at: https://news.mongabay.com/2019/05/tall-and-old-or-dense-and-young-which-kind-of-forest-is-better-for-the-climate/.
7. Climate change: Five cheap ways to remove CO2 from the atmosphere. (2018). BBC News. [online] 24 Oct. Available at: https://www.bbc.co.uk/news/science-environment-45967215.
8. Nunez, C. (2019). Carbon dioxide in the atmosphere is at a record high. Here’s what you need to know. [online] Environment. Available at: https://www.nationalgeographic.com/environment/article/greenhouse-gases.
9. Streiff, L. (2021). NASA Satellites Help Quantify Forests’ Impacts on Global Carbon Budget. [online] NASA. Available at: https://climate.nasa.gov/news/3063/nasa-satellites-help-quantify-forests-impacts-on-global-carbon-budget/.
10. Cho, R. (2019). State of the Planet. [online] State of the Planet. Available at: https://blogs.ei.columbia.edu/2018/02/21/can-soil-help-combat-climate-change/.
11. Trees for Life. (2019). Decomposition and decay | Trees for Life. [online] Available at: https://treesforlife.org.uk/into-the-forest/habitats-and-ecology/ecology/decomposition-and-decay/.
12. University of Arizona News. (2013). Dead Forests Release Less Carbon Into Atmosphere Than Expected. [online] Available at: https://news.arizona.edu/story/dead-forests-release-less-carbon-into-atmosphere-than-expected [Accessed 6 Apr. 2021].
13. www.cbsnews.com. (2020). Does planting a tree really offset your carbon footprint? [online] Available at: https://www.cbsnews.com/news/planting-a-tree-offset-your-carbon-footprint/.