Comparative Permanence Models in Voluntary Carbon Markets - Informing the American Forest Foundation’s Proposed Permanence Trust - ENVS 50 Environmental Problem Analysis and Policy Formation

Sep 24, 2026

Carbon markets use incentives to reduce greenhouse gas emissions, yet voluntary markets lack standardized models to evaluate carbon permanence and reversal risk. This paper analyzes comparative permanence and carbon-decay modeling approaches to support the American Forest Foundation’s proposed Permanence Trust, designed to ensure durable storage of carbon benefits from nature-based projects and compensate for future carbon losses. Using consistent definitions for permanence, reversals, credits, and crediting periods, the work benchmarks risks and identifies gaps for a more comprehensive, standardized decay model.

LanguageEnglish

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Introduction

Literature Review

Key organizations and players

Definitions and quantification gaps

ENVS 50: Environmental Problem Analysis and Policy Formation Dartmouth College Environmental Studies Program Hanover New Hampshire USA Advisors: Michael Cox and Karen Bieluch June 2025 Comparative Permanence Models in Voluntary Carbon Markets: Informing the American Forest Foundation’s Proposed Permanence Trust Ali Bauer, Anya Roodnitsky, Brian Arruda, and Sarah Olson Michael Cox and Karen Bieluch Environmental Problem Analysis and Policy Formulation 09 June, 2025 Introduction Carbon markets are a leading course of action to reduce greenhouse gas emissions (GHGs) through positive incentives. Increasing understanding of carbon markets and associated risk factors is crucial in the global mission to combat climate change, however, the landscape of voluntary carbon markets lacks accurate and standardized models to assess carbon permanence. In response, the American Forest Foundation (AFF), a nonprofit whose mission is to deliver meaningful conservation impact through the empowerment of family forest owners, is creating a Permanence Trust with the goal of developing a more effective system to monitor the durability of climate benefits and compensate for carbon losses when they occur. The Permanence Trust is a financial mechanism designed by the American Forest Foundation to guarantee that carbon benefits from nature-based projects (especially forest projects) remain stored over the long term, even if a future disturbance (such as a wildfire or pest outbreak) causes some of that sequestered carbon to be released. In essence, it functions like centralized “insurance” for carbon credits, ensuring they are equivalent to permanent geologic storage. This effort seeks to strengthen the credibility of natural climate solutions and unlock greater financial support for ecosystem restoration and conservation on a global scale. To frame the paper, consistent definitions are needed. Carbon permanence, as defined by the Climate Action Reserve (CAR), is when removing CO₂ from the atmosphere for 100 years is achieved by storing carbon in biological or geological reservoirs (Climate Action Reserve 2024, pp. 15). A reversal occurs when carbon that was previously sequestered or avoided by a project (like in a forest) is later released back into the atmosphere. Generally, reversals refer to reductions in forest biomass that cause CO₂ emissions, with reversal risk assessed by estimating the likelihood and severity of natural or anthropogenic disturbances such as wildfire, disease, drought, or deforestation (Isometric 2024) . A carbon credit is a quantifiable volume of carbon dioxide extracted from the atmosphere through activities such as forest conservation or restoration. For example, if a project has a 40-year crediting period, that means it can issue carbon credits for greenhouse gas reductions or removals that occur anytime within those 40 years. To mitigate reversal risk, mechanisms like buffer pools are employed; for example, Verra’s Pooled Buffer System requires projects to set asidea portion of credits based on assessed risk, pooling this reserve across projects in a collective insurance-like model to ensure 100-year credit integrity (Verra 2023) . Carbon crediting periods define the duration during which GHG reductions can be verified and credited—typically 10 years for non-sequestration projects and up to 100 years for sequestration projects, with ongoing monitoring to ensure permanence (Climate Action Reserve 2022) . Finally, carbon markets themselves are systems for trading carbon credits that represent verified emissions reductions or removals; these markets may be compliance-based, where reductions are mandated by law, or voluntary where organizations participate to meet self-imposed climate goals (CRS 2024) . Carbon decay models estimate how and at what rate sequestered carbon is released back into the atmosphere over time. This paper examines a range of existing tools and carbon decay models from leading

FAQs

What problem does the paper address in voluntary carbon markets?

Voluntary carbon markets lack accurate and standardized models to assess carbon permanence and associated risk factors, especially the durability of climate benefits over long time horizons.

How is carbon permanence defined in the paper?

Carbon permanence is defined as achieving 100 years of CO2 removal by storing carbon in biological or geological reservoirs, consistent with the Climate Action Reserve (CAR) definition.

What is the purpose of the American Forest Foundation’s proposed Permanence Trust?

It is a financial mechanism intended to guarantee that carbon benefits from nature-based projects remain stored over the long term, and to compensate for carbon losses when disturbances cause previously sequestered carbon to be released.

Sep 24, 2026

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