Tree Growth Profiles and What They Mean for Carbon Credit Vintages
Exploring the non-linear growth of trees to understand its connection and significance to carbon credit yields throughout project lifecycles
Carbon Credits
Science & Tech
Apr 24, 2024
Emily Houston
In a previous blog, we unpacked why the timing of vintages matters for credit issuances and purchases. To recap, a vintage is the year a carbon credit is generated. It is, therefore, the year that the emissions were avoided, reduced, or sequestered and the year in which a carbon credit can be verified and retired from a registry.
In this blog, we will cover another important aspect to consider when examining vintages—the amount of carbon generated from a nature-based project each year. Understanding this factor is especially important when procuring carbon credits through an offtake agreement.
Understanding carbon sequestration rates in forests is critical to building a voluntary carbon market based on strong scientific evidence and robust datasets.
Trees don’t grow at a constant rate - what does that mean for carbon sequestration?
The growth of a typical tree follows a growth pattern known as a sigmoid growth curve (S-curve). This means that once a seed is planted, growth is initially slow. Then, if in favourable conditions, growth exponentially increases as the tree grows rapidly in the middle of its life. Finally, growth slows down, with little to no visible ongoing growth.
Through a series of calculations, the above-ground biomass of the tree (the physical size of the trunk and branches) can be converted to provide an equivalent carbon figure. Thus, the larger a tree, the more carbon is held in its biomass and, therefore, the more carbon it has sequestered over its lifetime. In this respect, understanding the growth curve of a tree is crucial because it determines how much carbon is likely to be sequestered by a specific tree at any given point in its lifecycle. This is shown very simply in the illustration below. (Reference).
When planning and executing a nature-based carbon removal project, carbon curves must be considered. They illustrate, as above, the likely carbon sequestration of the project across its lifetime, using estimated growth profiles and growth curves derived mainly from the timber industry, where yield classes are used to indicate the number of cubic metres per hectare that given trees are putting on annually. The carbon curves produced give project developers and financiers an understanding of the gross potential yield of a project. These carbon curves are also critical to carbon offtake buyers, who must procure specific carbon volumes yearly.
The carbon sequestration curve and its importance in offtakes
As explained above, carbon sequestration is an S-curve; therefore, the amount of carbon a project generates per vintage will vary across its lifetime. Buying a carbon offtake agreement for 10,000 tonnes over ten years does not mean you will have 1,000 retriable credits issued to you each year. The volumes will vary throughout the project's life, and the underlying trees. You may get only a few tens of tonnes in the first years, increasing to a few thousand as the forest grows and matures. As a buyer, if you have a carbon footprint for which you require retriable credits annually, understanding this before you enter into a carbon offtake agreement is essential.
An important takeaway is that these calculations and carbon sequestration projections are based on timber-derived estimations. They are robust and provide a solid starting point for global carbon standards. However, technology is developing and providing new, more granular information on forest growth that can be specifically applied to carbon.
Remote sensing for more accurate carbon stock assessments
Remote sensing allows us to evaluate closely, on a project-by-project basis, if a forest is growing in line with what the yield calculations would predict. Keeping in mind the carbon curves are predictions of sequestration across the project's lifecycle, ongoing monitoring to confirm what is actually happening is essential. Is a project overperforming? If so, is a species-driven disaggregation causing this or site-specific factors? Is a project underperforming? If so, what empirical evidence do we have of what is causing this, and how can we apply these learnings to other project sites?
Why does all of this matter?
- This matters for buyers, particularly those acquiring carbon credits through offtake agreements. It offers them greater certainty regarding the delivery of carbon credits through such agreements by providing a clearer understanding of carbon yields throughout a project's lifecycle.
- This matters for project developers as it enables them to pre-sell carbon more effectively by providing buyers with a more accurate estimate of potential carbon yield over the project's lifecycle. This assurance can facilitate project financing earlier.
- This matters for the market, as increased transparency in carbon sequestration estimation and carbon credit pricing instils confidence among corporates and investors to invest in pre-development projects through offtake agreements. This is crucial for initiating more nature-based projects and achieving the necessary carbon removal levels to expand and scale the voluntary carbon markets (VCM) in the fight against climate change.
- This matters for science, as it encourages the development of more accurate tree growth models across a project's lifespan. This, in turn, enhances the quantification of carbon sequestration by leveraging remote sensing and fosters greater trust in nature-based carbon removal projects.
How Treeconomy can help
If this blog on the impact of tree growth profiles on carbon credits has piqued your interest in projects offering more accurate carbon quantification across their lifecycle – Treeconomy can help!
Explore our marketplace for a curated selection of high-quality, nature-based carbon removal projects, all monitored and analysed using our remote sensing technology. Within the platform, you'll find a vintage-by-vintage breakdown for each project, ensuring you have all the necessary information to understand how many carbon credits will get delivered and when.
We offer various innovative ways to support projects, including offtake agreements that allow engagement from an early stage, with the assurance of more accurate and transparent carbon stock assessments.
Don't hesitate any longer. Explore our marketplace or contact us at hello@treeconomy.co to take the first step toward achieving your climate targets.
