‘How much carbon dioxide (CO2) does a tree absorb?’ is a fundamental question to address in the fight against climate change. Climate model scenarios indicate that we need to remove billions of tons of CO2 from the atmosphere. They also demonstrate that we need to significantly reduce our emissions to prevent global warming exceeding 2°C.1 Trees are a central nature-based solution to this problem because they naturally absorb carbon and can store it for centuries.2
Why do we need trees to absorb carbon dioxide (CO2)?
We need trees to absorb carbon to reduce the atmospheric CO2 concentration. Trees pull the element directly out of the air and use it to make food via photosynthesis. They also produce oxygen in the process. This is key to preventing climate change because carbon dioxide is a contributor to global warming.3
Greenhouse gases, such as CO2, prevent heat from escaping from Earth in a process known as the greenhouse effect.4 This helps to raise the planet’s overall temperature. Humans have increased the amount of CO2 in the atmosphere by 47 per cent since the Industrial Revolution by burning fossil fuels.5 It is now at its highest level for at least 800,000 years.6 Every decade, anthropogenic planetary warming increases at 0.2°C due to past and ongoing emissions in the atmosphere.7
The Intergovernmental Panel on Climate Change (IPCC) is unequivocal that a global rise of temperature 2°C above pre-industrial levels would be disastrous for our planet.8 It is clear that if human activities producing greenhouse gases continue at the current rate, 1.5°C of warming is likely to be reached between 2030 and 2052.9 196 Parties representing the majority of the world’s nations agreed to limit global warming to well below 2°C by signing the Paris Climate Agreement in 2015.10
How much CO2 does a tree absorb in a day?
The amount of CO2 a tree absorbs in a day varies between different species.11 Saplings also absorb much less carbon compared to older trees. However, on average, a mature tree pulls about 21 kilograms of CO2 per year from the atmosphere.12 Over a typical lifetime of 100 years, a single tree will absorb a tonne of greenhouse gas.13 One acre of forest can therefore offset twice the CO2 produced by the average car’s mileage.14
Trees are one of the most powerful weapons we have to combat global warming. They are one of the cheapest and most efficient tools for reducing atmospheric concentrations of CO2.15 We should continue to engage in planting trees for this reason and for the role they play in supporting biodiversity.
How many trees would we need per year to offset climate change?
However, we cannot rely on trees entirely for climate change mitigation. Humans create about 40 billion tonnes of CO2 every year.16 We would therefore need to plant 40 billion trees annually to offset these emissions.17 Not only is limited land available for this, but trees also take years to absorb serious quantities of carbon. We do not have enough time before the world’s temperature increases above 1.5°C.
How can we limit global warming to well below 2°C?
Tree planting and reducing deforestation
To limit global warming to well below 2°C – and preferably to 1.5°C – two principal approaches must be taken. Firstly, we must protect the forests we already have and enhance them with tree planting and other initiatives. Current nature-based solutions may provide as much as a third of the cost-effective climate mitigation needed. For this to materialise, careful management, protection and restoration of our existing forests, wetlands, grasslands and agricultural lands will be necessary.18
Unfortunately, we are not currently approaching the natural world in a sustainable way to mitigate climate change. Deforestation, particularly in the tropics, remains rampant with an area of forest the size of the UK lost annually.19 This is disastrous, given how much CO2 trees absorb. Tropical forest is a vital part of climate mitigation. They hold more than 210 gigatons of carbon, equivalent to seven times our annual anthropogenic carbon emissions.20
Sadly, in many of the world’s rainforests, deforestation is increasing. In 2020, the rate of deforestation in the Amazon rainforest reached its highest point since 2008.21 A similar situation persists in the second lungs of the world, the Congo Basin. Annual deforestation in the Congo has increased recently, with more than one million hectares cut down each year.22 Deforestation globally accounts for about eight to 10 per cent of all greenhouse gas emissions.23 If this imprudent practice continues, most of the world’s forest will be gone, fragmented or utterly degraded by the end of the century.24
Curtailing greenhouse gas emissions
A massive reduction in greenhouse gas emissions is also necessary to prevent global warming. There is no time left to postpone action on this issue. Global emissions rose 62 per cent between 1990 and 2019. The atmospheric concentration of CO2 continues to increase to new dangerously high levels.25 These emissions are driving climate change and threatening our planet.
Close to three-quarters of all emissions come from the energy sector. This includes heating and electricity production and transportation. Energy usage for industries such as iron and steel, chemical and petrochemical, and cement production are among the worst emissions culprits.26
Moreover, agriculture, forestry and land use directly account for 18.4 per cent of greenhouse gas emissions.27 Cutting down trees and either burning them or leaving them to rot releases carbon stored in their biomass and the surrounding soil.28 Farming livestock produces large quantities of methane, an especially active greenhouse gas.29
A significant change in how we produce energy is needed. Equally, we all need to examine our own lifestyle choices and reduce our carbon footprints by avoiding meat and dairy products or flying less, for example.
What will happen if we continue to remove our trees?
We cannot achieve the climate change goals outlined by the IPCC and the Paris Agreement without protecting and enhancing our forests and other natural carbon sinks, for instance by planting more trees. If we lose them, a catastrophic increase in global temperatures above 2°C is inevitable.30 A mass extinction would ensue with devastating repercussions for biodiversity since 80 per cent of terrestrial species live in forests.31 It would also plunge the 1.6 billion people who depend on them for their livelihoods into poverty or worse.32
How many essential reasons to save our trees do we need before we stop cutting them down for quick profits?
Sources
- IPCC (2018). Summary for Policymakers — Global Warming of 1.5 oC. [online] Ipcc.ch. Available at: https://www.ipcc.ch/sr15/chapter/spm/.
- Penn State Extension. (n.d.). How Forests Store Carbon. [online] Available at: https://extension.psu.edu/how-forests-store-carbon.
- Pirates, C. (2019). How much Carbon does one Tree absorb? [online] CarbonPirates. Available at: https://www.carbonpirates.com/blog/how-much-carbon-do-trees-absorb/.
- NASA (2018). The Causes of Climate Change. [online] Climate Change: Vital Signs of the Planet. Available at: https://climate.nasa.gov/causes/.
- NASA (2018). The Causes of Climate Change. [online] Climate Change: Vital Signs of the Planet. Available at: https://climate.nasa.gov/causes/.
- Lindsey, R. (2020). Climate Change: Atmospheric Carbon Dioxide | NOAA Climate.gov. [online] Climate.gov. Available at: https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide.
- IPCC (2018). Summary for Policymakers — Global Warming of 1.5 oC. [online] Ipcc.ch. Available at: https://www.ipcc.ch/sr15/chapter/spm/.
- IPCC (2018). Summary for Policymakers — Global Warming of 1.5 oC. [online] Ipcc.ch. Available at: https://www.ipcc.ch/sr15/chapter/spm/.
- IPCC (2018). Summary for Policymakers — Global Warming of 1.5 oC. [online] Ipcc.ch. Available at: https://www.ipcc.ch/sr15/chapter/spm/.
- United Nations Climate Change (2016). The Paris Agreement | UNFCCC. [online] Unfccc.int. Available at: https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement.
- http://treeplantation.com (n.d.). Tree Carbon Calculator. [online] Tree Plantation. Available at: https://www.treeplantation.com/tree-carbon-calculator.html.
- www.viessmann.co.uk. (n.d.). How much CO2 does a tree absorb? [online] Available at: https://www.viessmann.co.uk/heating-advice/how-much-co2-does-tree-absorb.
- www.viessmann.co.uk. (n.d.). How much CO2 does a tree absorb? [online] Available at: https://www.viessmann.co.uk/heating-advice/how-much-co2-does-tree-absorb.
- Tenmilliontrees.org. (2018). All About Trees. [online] Available at: http://www.tenmilliontrees.org/trees/.
- Carrington, D. (2019). Tree planting “has mind-blowing potential” to tackle climate crisis. [online] the Guardian. Available at: https://www.theguardian.com/environment/2019/jul/04/planting-billions-trees-best-tackle-climate-crisis-scientists-canopy-emissions.
- www.viessmann.co.uk. (n.d.). How much CO2 does a tree absorb? [online] Available at: https://www.viessmann.co.uk/heating-advice/how-much-co2-does-tree-absorb.
- www.viessmann.co.uk. (n.d.). How much CO2 does a tree absorb? [online] Available at: https://www.viessmann.co.uk/heating-advice/how-much-co2-does-tree-absorb.
- Griscom, B.W., Adams, J., Ellis, P.W., Houghton, R.A., Lomax, G., Miteva, D.A., Schlesinger, W.H., Shoch, D., Siikamäki, J.V., Smith, P., Woodbury, P., Zganjar, C., Blackman, A., Campari, J., Conant, R.T., Delgado, C., Elias, P., Gopalakrishna, T., Hamsik, M.R. and Herrero, M. (2017). Natural climate solutions. Proceedings of the National Academy of Sciences, [online] 114(44), pp.11645–11650. Available at: https://www.pnas.org/content/114/44/11645.
- correspondent, F.H.E. (2019). World losing area of forest the size of the UK each year, report finds. The Guardian. [online] 12 Sep. Available at: https://www.theguardian.com/environment/2019/sep/12/deforestation-world-losing-area-forest-size-of-uk-each-year-report-finds#:~:text=The%20rate%20of%20loss%20has.
- World Wildlife Fund. (n.d.). Forest Habitat | Habitats | WWF. [online] Available at: https://www.worldwildlife.org/habitats/forest-habitat#:~:text=Eighty%20percent%20of%20the%20world.
- Silva Junior, C.H.L., Pessôa, A.C.M., Carvalho, N.S., Reis, J.B.C., Anderson, L.O. and Aragão, L.E.O.C. (2021). The Brazilian Amazon deforestation rate in 2020 is the greatest of the decade. Nature Ecology & Evolution, [online] 5(2), pp.144–145. Available at: https://www.nature.com/articles/s41559-020-01368-x [Accessed 14 Feb. 2021].
- Mongabay Environmental News. (2020). Poor governance fuels “horrible dynamic” of deforestation in DRC. [online] Available at: https://news.mongabay.com/2020/12/poor-governance-fuels-horrible-dynamic-of-deforestation-in-drc/.
- Dean, A. (2018). How does deforestation contribute to climate change? – Climate Council. [online] Climate Council. Available at: https://www.climatecouncil.org.au/deforestation/.
- Vidal, J. (2018). We are destroying rainforests so quickly they may be gone in 100 years | John Vidal. [online] the Guardian. Available at: https://www.theguardian.com/global-development-professionals-network/2017/jan/23/destroying-rainforests-quickly-gone-100-years-deforestation.
- Nations, U. (n.d.). Key Findings. [online] United Nations. Available at: https://www.un.org/en/climatechange/science/key-findings.
- Ritchie, H. (2020). Sector by sector: where do global greenhouse gas emissions come from? [online] Our World in Data. Available at: https://ourworldindata.org/ghg-emissions-by-sector.
- Ritchie, H. (2020). Sector by sector: where do global greenhouse gas emissions come from? [online] Our World in Data. Available at: https://ourworldindata.org/ghg-emissions-by-sector.
- Marshall, M. (2020). Planting trees doesn’t always help with climate change. [online] www.bbc.com. Available at: https://www.bbc.com/future/article/20200521-planting-trees-doesnt-always-help-with-climate-change.
- NASA (2018). The Causes of Climate Change. [online] Climate Change: Vital Signs of the Planet. Available at: https://climate.nasa.gov/causes/.
- IPCC (2018). Summary for Policymakers — Global Warming of 1.5 oC. [online] Ipcc.ch. Available at: https://www.ipcc.ch/sr15/chapter/spm/.
- World Wildlife Fund. (n.d.). Forest Habitat | Habitats | WWF. [online] Available at: https://www.worldwildlife.org/habitats/forest-habitat#:~:text=Eighty%20percent%20of%20the%20world.
- World Wildlife Fund. (n.d.). Forest Habitat | Habitats | WWF. [online] Available at: https://www.worldwildlife.org/habitats/forest-habitat#:~:text=Eighty%20percent%20of%20the%20world.