TreeSisters Tree References

Estimation of CO2 uptake in TreeSisters’ reforestation projects

By Lauriane Cayet-Boisrobert 

Interest has been increasing regarding TreeSisters’ stand on carbon offsetting,
and requests to offset certain activities through our reforestation projects. 

Because of these enquiries, we have calculated the emission reduction potential across our reforestation project portfolio as of August 2019 - across eight projects located in various locations in the tropics.  Our methodology is described here.  

We’re offering this estimate to help increase understanding about the vast capacity that tropical forests and trees have to help cool our world, as they draw carbon out of the atmosphere. Tropical forests are the largest terrestrial carbon reservoirs on our planet.  

Before we get to the calculation, it feels important to share that as an organisation we have chosen a different route than the carbon offset path for various reasons (and then we will give you a calculation to make!) 

Firstly, TreeSisters looks through the multifaceted lens of living systems (of which carbon is one facet) which are complex, interdependent, multi-species communities that provide vital ecosystem services that have foundational importance to the whole web of life. To measure carbon without looking at water, soil, biodiversity, oxygen etc is like looking at the bones of a human and ignoring the rest. In just looking at carbon offsets, we ‘lose’ what a forest is, and we completely miss the subtle and the sacred.

Secondly, calculating carbon tends to be reductionist rather than generative or generous. It can steer towards the least that can be done to feel good, rather than the most that can be done to do good. Forest plantations are a preferred means for offsetting carbon, but they provide relatively few benefits to native biodiversity and watershed health.

If your house was on fire, would you expect your neighbours to stand by trying to assess how much of it they might have been responsible for, before getting a watering can and watering a few flames? Or would you want them to give it all they’d got to put out the fire? Because our world is on fire, TreeSisters has chosen the latter, rather than the former position. 

Having said that, we are not ‘against’ the activity of offsetting, and indeed it needs to happen. It’s just that wildly more than that needs to happen for us to touch the edges of this fire. TreeSisters will always be a call for the most that you are able to do, in terms of radical generosity.  If you figure out the most that you can do, we will plant trees for you.

The Carbon Sequestration Potential of the TreeSisters Portfolio as of August 2019:

  • We estimate that nearly 800,000 tonnes of carbon dioxide (CO2) will be sequestered over 20 years, from the 6 million trees funded (1) by TreeSisters. These numbers are our best estimation.
  • We estimate that for every £3 or USD$4 donated1 tonne of carbon dioxide is drawn down over 20 years. This is equivalent to the CO2  emitted for a round trip when one person is flying from London Heathrow to New York John F. Kennedy and back. (2)
  • At £0.40 per tree, a donor who gives £10 per month for one year funds approximately 300 trees per year and sequesters 40 tonnes of carbon dioxide which will be drawn out of the atmosphere over a 20 year period. As a comparison, 40 tonnes of carbon dioxide is equivalent to what’s emitted when charging your smartphone 5 million times or of 8.5 passenger vehicles driven for one year in the United States. (3)

Note: these estimates should be used with caution bearing in mind the limitations discussed here.

TreeSisters is not a carbon offset provider. We do not issue carbon certified units or credits, and none of our current projects are carbon certified. We can’t lead complex experimental work and research that’s required (4) to reach the level of accuracy needed to issue valid carbon credits ‒ we instead focus our finances and energy on ethical and effective reforestation. 

Nevertheless, if you decide to address your carbon footprint, we can offer a quick and easy way for you to compensate for your carbon emissions, by running a simple calculation and donating to our reforestation projects. 

This is a quick method to compute how many trees to fund to help offset your carbon footprint:

  1. Calculate your footprint at a site like
  2. For every tonne of carbon dioxide you have emitted, allocate £3 or USD$4 to plant trees.
  3. Understand that these trees will sequester that carbon over 20 years.
  4. Make a donation here and your account will show your number of trees.
  5. Note: adding/removing reforestation projects to our portfolio may slightly change the estimates, and thus the amount to donate per 1 tonne of carbon emitted may vary

You might also be interested in:

~Joining or starting a local movement of people who stand for planetary care, and flourish in a variety of ways including local tree planting by joining or creating a Reforestation Grove;
~ Educating about trees and reforestation by organizing a Tree Conference in your area;
~ Embedding ecological restoration into your business by becoming a Company Partner.

To learn more about the important role of tropical forests and trees in the water cycle and weather patterns, read this article.

To learn more about our projects please visit our Tree page..

To make a donation to support this work please visit our Give page.

Written by Lauriane Cayet-Boisrobert
Published February 27, 2020
Top photo by WeForest

Lauriane Cayet-Boisrobert
is our Reforestation Programme Manager. She develops and manages our reforestation projects portfolio. She started by co-developing TreeSisters' forest strategy and project selection process. Lauriane is passionate about the many cultures on Earth. She tries to live in harmony with the Earth; so the Earth must stay wild and generous to us all. She feels deeply sad when the Earth is been abused at all prices, and mostly at the expenses of the people who rely on it.

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1. Trees funded have been either planted, are being planted within a year, or are assisted to naturally regenerate and thus would emerge progressively over 20 years time.

2. Figures from published by the Guardian Newspaper 19th July 2019.
3. US EPA, OAR. “Greenhouse Gases Equivalencies Calculator - Calculations and References.” Data and Tools. US EPA, August 10, 2015.  Available here.
4. They require the collection of field data and make use of complex model simulations and remote sensing data that is complex and costly to acquire.
5. In 2019, TreeSisters started funding new reforestation projects in Mozambique, in West Papua and in the Brazilian Amazon, which are not accounted for here.