Do you know which tree absorbs the most CO2? You may be surprised.

Currently, our world is having to grapple with rising carbon dioxide emissions – 36 billion tons per year – which are heating up the planet.¹ To tackle this crisis, scientists are increasingly examining how trees can help us to remove carbon emissions from the atmosphere. While trees are not a silver bullet, a growing number of scientists are advocating for large tree-planting programs.

This raises a fundamental question, which tree is the most relevant in CO2 reduction? This can help us to understand which trees need to be planted.

Which tree absorbs the most CO2? 

This isn’t a theoretical question. The world could “erase 100 years of carbon emissions” by planting native trees across an area the size of the United States, as outlined by a major study in 2019. “If we act now, this could cut carbon dioxide in the atmosphere by up to 25 per cent, to levels last seen almost a century ago”, said a senior author of the study, which was published in the journal ‘Science’.²

How do trees reduce CO2?

The answer to this question also isn’t straightforward. It depends on the species of tree and its level of maturity. Trees absorb CO2 during photosynthesis. In this process, they use water, sunlight and carbon to produce energy and oxygen. The carbon is used to build their organic material, such as stems, leaves and wood.³

In other words, large trees with dense wood usually absorb the most carbon dioxide. Species such as pines, conifers, oak trees, and other deciduous tree species, such as the horse-chestnut tree, absorb relatively large amounts of carbon dioxide.⁴ Moreover, as trees grow older, they also grow faster and become more efficient at absorbing CO2. This makes older trees better at absorbing carbon dioxide than younger ones.⁵ However, some scientists maintain that younger forests absorb more carbon overall because small trees in younger forests can be placed closer together.⁶ Older forest trees, on the other hand, tend to be more spaced out.

Consequently, it’s not always clear which tree absorbs the most CO2. But, we know that cutting down trees releases the stored CO2 back into the air, and therefore it is better for the environment to stop cutting them down.

Is tree planting the solution to climate change?

While trees are currently the best solution to remove CO2 from the air, they are by no means a silver bullet. They cannot and should not replace the need to reduce carbon dioxide emissions from factories, homes and transport. We would have to plant millions of trees every year to compensate for worldwide CO2 emissions. Climate change is a complex problem that requires a combination of approaches. Tree planting alone will not fix it.⁷

1. Ritchie, H. and Roser, M. (2017). CO2 emissions. [online] Our World in Data. Available at: https://ourworldindata.org/co2-emissions.
2. Environment. (2019). How to erase 100 years of carbon emissions? Plant trees. [online] Available at: https://www.nationalgeographic.com/environment/article/how-to-erase-100-years-carbon-emissions-plant-trees.
3. BBC (2019). What is photosynthesis? [online] BBC Bitesize. Available at: https://www.bbc.co.uk/bitesize/topics/zvrrd2p/articles/zn4sv9q.
4. Norris, L. (2011). What Trees Absorb the Most Carbon Dioxide? | Hunker. [online] Hunker. Available at: https://www.hunker.com/12557632/what-trees-absorb-the-most-carbon-dioxide.
5. Pacific Forest Trust. (2014). E&E: Old trees store more carbon, more quickly, than younger trees. [online] Available at: https://www.pacificforest.org/ee-old-trees-store-more-carbon-more-quickly-than-younger-trees/.
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. Science, A.A. for the A. of (2020). Erratum for the Report: “The global tree restoration potential” by J.-F. Bastin, Y. Finegold, C. Garcia, D. Mollicone, M. Rezende, D. Routh, C. M. Zohner, T. W. Crowther and for the Technical Response “Response to Comments on ‘The global tree restoration potential’” by J.-F. Bastin, Y. Finegold, C. Garcia, N. Gellie, A. Lowe, D. Mollicone, M. Rezende, D. Routh, M. Sacande, B. Sparrow, C. M. Zohner, T. W. Crowther. Science, [online] 368(6494). Available at: https://science.sciencemag.org/content/368/6494/eabc8905.