Some of the world’s most powerful work is done in silence. Underground, in the roots of trees. In the slow layering of soil. In the thickening of trunks and the unseen molecules drifting between atmosphere and leaf.
This is carbon sequestration—the quiet capture of carbon dioxide from the air, locked away in forests and their shadows. It is nature’s ancient response to excess, and perhaps humanity’s last great ally in the fight against climate change.
But how do we value this silence? How do we measure the invisible?
In Chapter 7 of Applied Environmental Economics, the authors attempt just that: to model and assign economic value to carbon stored in live trees, harvested wood products, and the very soils beneath our feet. It is one of the most technically intricate chapters—and one of the most urgent.
What Is Carbon Sequestration Worth?
When we think of forests storing carbon, we often imagine only the trees. But in truth, the carbon cycle in a woodland is complex. Carbon is:
- Sequestered in growing biomass (branches, trunks, leaves).
- Transferred into timber products—furniture, construction, paper.
- Released over time as those products degrade or burn.
- Stored or emitted through changes in forest soils, which can gain or lose carbon depending on land use history and tree type.
To model this system, the authors distinguish between these compartments and trace carbon over time—tracking how long it stays “locked up,” and when it returns to the atmosphere.
This time element is crucial. A carbon atom stored in a house beam for 80 years is not the same as one released tomorrow. It’s this temporal dance that makes carbon valuation both powerful and delicate.
Discounting the Future, Again
Just as with timber value, economists use Net Present Value (NPV) to account for time in carbon sequestration. But here, the ethical implications deepen.
If you value the future less (with a high discount rate), then long-term carbon storage seems less important. If you value the future more (with a low discount rate), forests become goldmines of climate benefit.
The chapter explores both ends of the spectrum—modelling carbon NPVs at different rates and showing just how much this affects whether forestry looks “worth it” on paper.
But behind the numbers lies a philosophical question: How much do we care about tomorrow’s atmosphere?
Tree Species and Sequestration Patterns
The research focuses on two common UK tree species: Sitka spruce and beech. Sitka grows quickly and sequesters carbon rapidly but is often used in short-lived products like paper. Beech grows more slowly but is often used in longer-lasting products—and affects soil differently.
Each species has a different carbon profile over time. The authors model these profiles through forest lifecycles, accounting for:
- Growth and thinning cycles.
- Harvest timing.
- Allocation to different product types (e.g., sawtimber vs. pulp).
- Decomposition and combustion rates.
- Soil carbon changes based on land conversion scenarios.
By doing this, they produce carbon flux timelines—charts that show how carbon moves in and out of the system, year by year.
The results? A deeply spatial, deeply temporal view of sequestration. Forests aren’t static carbon sinks—they are dynamic systems, and their climate benefit depends on how we manage them.
The Soil Beneath Our Models
One of the chapter’s most innovative contributions is its inclusion of forest soil in the sequestration analysis.
When agricultural land is converted to woodland, soils can store more carbon—but not always. The effect depends on initial land use, soil type, and the chosen tree species. Sometimes, conversion leads to a temporary loss of soil carbon before gains emerge decades later.
Modelling this requires linking forest data with detailed soil maps (from the LandIS database) and incorporating long-term soil carbon equilibrium curves.
This is climate modelling at the ground level. Literally.
Turning Carbon into Currency
Once sequestration is modelled, the next step is valuation.
What is one tonne of stored carbon worth?
The answer depends on social cost estimates—figures representing the economic damage avoided by not releasing that carbon. The chapter surveys a range of values from past studies and applies them to their models, calculating the monetary value of carbon stored by Sitka and beech plantations under various scenarios.
At low discount rates and with moderate carbon prices, the value of sequestration is substantial—often comparable to or exceeding timber value itself.
Which means that in many cases, planting trees for carbon may be as justifiable economically as planting them for wood.
Why This Matters
This chapter is not just academic. Its findings touch real decisions—about land use, climate policy, farm subsidies, and even how nations meet their international commitments.
If we undervalue carbon sequestration, forests will lose to farmland. If we ignore soil, we may miscalculate our gains. And if we apply high discount rates, we may mortgage the future for fleeting present benefits.
But if we model carefully, map accurately, and price wisely, then forests become more than scenery. They become strategic assets—climate allies that generate value by standing tall, not just by being cut.
Closing Reflections
Carbon sequestration is invisible. But its impact is not.
It is stored in the shade of woodlands, in beams of homes, in the softness of leaf-covered soil. It is the breath we don’t see—the atmosphere we share with every living thing.
And now, at last, it has a number. A model. A value.
So when we plant a tree today, we do more than shape the landscape. We shape the air. And in that act, we choose a quieter, more stable tomorrow.