Impact
Trees remove methane through their bark. A restoration claim would require evidence that a payment changed a documented project decision. The spatial model estimates which grid cells meet a 12% required return. The spatial model also estimates peak funding need. A separate completion scenario applies an assumed response that has not been fitted to observed project data.
16.8 kg
CH₄/ha/year
Upper-end tropical uptake used in the model
0.45 t
CO₂e/ha/year
GWP100 value before project deductions
+1.7 Mha
at $50, GWP100
Increase in modeled bankable area
+6.5 Mha
at $50, GWP*
New-sink scenario with full uptake from year one
The area figures report modeled bankability. They do not report planted or delivered forest. No carbon registry currently credits bark methane. The GWP* results are a separate accounting scenario.
Project causation
A restoration claim requires a future project decision. Project records must show that the payment changed that decision.
An advance purchase can contribute to a documented financing gap. A restoration claim would require evidence that the purchase changed the planting decision.
Evidence needed
Affected hectares, budget gap, planting schedule, and financing decision
New funding can support remaining planting, maintenance, monitoring, or continuation when those activities still depend on finance.
Evidence needed
Unfunded work, timing, use of proceeds, and the consequence without the purchase
A new purchase cannot be credited with past planting. It can fund methane measurement or affect a later expansion or a separate project.
Evidence needed
Existing uptake reported separately from any later restoration decision
A modeled methane price changes which sites meet the required return. Developer records would be needed to show that the price changed site selection or delivery.
Evidence needed
Pipeline budgets, site decisions, capital allocation, and project outcomes
Advance purchase before planting
A prepayment can contribute to financial close or a defined expansion. The study does not model an advance-purchase transaction.
Revenue from issued credits
In the spatial model, credit revenue arrives one year after removal. Under that assumption, methane reduces peak funding need across land already bankable at $50 by 1.3% under GWP100 and 4.5% under GWP*.
Additionality
Field measurements establish physical uptake. The host-project method must establish the forest counterfactual. An approved methane method must define credit eligibility. Project records must connect a purchase to a decision. Separate models estimate the wider market response.
Are the trees removing methane, and how much? Field measurements estimate the flux, and the forest inventory scales it across the eligible area.
Would the forest have been restored or protected without the underlying project? The host forest method must answer this question.
An approved method must define the methane baseline, uncertainty, leakage, permanence, and controls against overlapping claims.
Which present decision changes because of this purchase? The answer may concern planting, completion, expansion, or measurement.
How does a methane price change later project development across many sites? The spatial and finance models test this effect under stated assumptions.
For trees already growing, a buyer did not cause the original planting. We report uptake on those trees separately. A claim for additional restoration would require the host project to meet additionality rules, an approved methane method, and project records showing that the purchase changed a financing or planting decision.
Spatial model
The model evaluates a 30-year reforestation project in 5.35 million one-kilometer grid cells covering 89.0 million hectares of constrained tropical restoration land. Each cell uses mapped forest growth and net agricultural income. The model assigns a project type and its fixed costs, then calculates a break-even carbon price with and without prospective methane revenue. Across the modeled area, methane increases the present value of credit revenue by an area-weighted average of 2.9% under GWP100 and 10.8% under GWP*.
Bankable at $50 without methane
32.0 Mha
This is the modeled base at a 12% required return.
Newly bankable under GWP100
+1.7 Mha
This is the modeled increase at $50 per tonne.
Newly bankable under GWP*
+6.5 Mha
The model treats GWP* as a separate new-sink scenario.
| Credit price | Without methane | With GWP100 | With GWP* |
|---|---|---|---|
| $20 | 5.1 Mha | 5.5 Mha | 6.4 Mha |
| $50 | 32.0 Mha | 33.7 Mha | 38.5 Mha |
| $75 | 59.9 Mha | 61.7 Mha | 66.3 Mha |
Across three assumed price distributions
GWP100+0.8 to 1.7 Mha
Separate GWP* scenario
GWP*+3.1 to 6.3 Mha
The weighting uses assumed carbon-price distributions. Observed transaction volumes are not an input. At higher prices, more land is bankable without methane, so methane adds fewer newly bankable hectares.
Project delivery
A bankable grid cell meets the required return. Financing and completion are two factors that affect delivery. The model reports them separately, and the results below should not be added.
Each step is conditional. The model does not estimate advance-purchase effects, and a project claim requires records showing that the purchase changed the decision.
Prospective methane revenue lowers each grid cell's break-even carbon price. Some marginal sites then meet the model's 12% required return.
The modeled increase is 0.8 to 1.7 Mha under GWP100 across the demand scenarios tested.
In the spatial cash-flow model, annual methane revenue reduces peak funding need. The model assumes that credit revenue arrives one year after removal. It does not estimate an advance-purchase transaction.
Peak funding need falls 1.3% under GWP100 and 4.5% under GWP*.
The scenario assumes that completion rates rise with project returns on land that was already bankable. At $50, it applies to about 32 Mha bankable without methane.
The scenario estimates an increase in completed area of 0.3 to 0.5 Mha under GWP100 and 1.2 to 1.9 Mha under GWP* at $50. The completion response has not been fitted to observed project data.
2.6 Mha
per percentage point near a 12% required return at $50
The required return is a major sensitivity. The study does not estimate how much methane revenue would lower that rate. Any methane-attributed reduction remains a labeled scenario.
Finance and land constraints
The model does not multiply the bankable-area result by the financing result. The cases below are conceptual scenarios. Current evidence does not identify which constraint limits a specific market or project portfolio.
Scenario: finance is scarce
More land meets the return threshold. Scarce finance leaves much of it unbuilt. The modeled funding need and completion assumptions determine the conditional effect. Advance purchases remain outside the model.
Scenario: capital is abundant
When finance can cover all bankable land, reducing funding need does not add hectares. Bankable land and completion determine the conditional effect.
Methane accounting
The reforestation scenario initializes methane uptake at zero and assumes the full mature uptake rate from year one. For that modeled step change, the annual GWP* value is about four times the GWP100 value for 20 years and about one quarter of it after year 20. If uptake began before measurement, the measurement date cannot be used as the sink's establishment date.
Years 1 to 20
~1.81 tCO₂-we/ha/year
This gross value is about four times the GWP100 value for a newly established constant sink.
After year 20
~0.11 tCO₂-we/ha/year
This gross value is about one quarter of the GWP100 value while the sink remains stable.
Our 2024 Nature study did not measure how uptake develops as restored forests age. Full mature uptake from year one is an explicit model assumption.
Published supply curves
An earlier calculation estimates a central reforestation supply elasticity near 1.0 from published supply curves. Near the prices tested, this means that a 1% increase in effective project revenue corresponds to about a 1% increase in modeled reforestation supply. The spatial model provides the main estimate on this page. The elasticity result is reported separately.
Central elasticity
~1.0
The estimate is derived from published tropical reforestation supply curves.
The calculation applies the modeled revenue change to published global reforestation potential. The high case uses GWP*, the high biological potential estimate, and an elasticity of 2.0. This provides a separate comparison with the spatial result. It is not an estimate of SelvaFlux project delivery or purchase attribution.
Evidence and assumptions
Published measurements provide the methane and forest-growth inputs. Other results depend on model choices or scenario assumptions.
Published or measured inputs
Core model choices
Scenario assumptions
Evidence still needed
A separate illustrative project calculation uses simplified costs and timing. Under its selected inputs, methane reduces peak funding need. We do not use that result as a study estimate. The spatial cash-flow model provides the funding-need figures on this page.
Sources