Carbon credits purchased in the voluntary carbon market allow unavoidable emissions, such as from international flights for essential travel, to be offset by an equivalent climate benefit, such as avoiding emissions from tropical deforestation. However, many concerns regarding the credibility of these offsetting claims have been raised. Moreover, the credit market is manual, therefore inefficient and unscalable, and non-fungible, therefore illiquid. To address these issues, we propose an efficient digital methodology that combines remote sensing data, modern econometric techniques, and on-chain certification and trading to create a new digital carbon asset (the PACT stablecoin) against which carbon offsetting claims can be transparently verified. PACT stablecoins are produced as outputs from a reproducible computational pipeline for estimating the climate benefits of carbon offset projects that not only quantifies the CO2 emissions involved, but also allows for similar credits to be pooled based on their co-benefits such as biodiversity and jurisdictional attributes, increasing liquidity through fungibility within pools. We implement and evaluate the PACT carbon stablecoin on the Tezos blockchain, which is designed to facilitate low-cost transactions while minimizing environmental impact. Our implementation includes a contract for a registry for tracking issuance, ownership, and retirement of credits, and a custodian contract to bridge on-chain and off-chain transactions. Our work brings scale and trust to the voluntary carbon market by providing a transparent, scalable, and efficient framework for high integrity carbon credit transactions.

翻译：在自愿碳市场中购买的碳信用额度允许将不可避免的排放（例如国际航班必要旅行产生的排放）通过同等的气候效益（如避免热带森林砍伐产生的排放）进行抵消。然而，人们对这些抵消声明的可信度提出了诸多质疑。此外，碳信用市场目前仍依赖人工操作，因此效率低下、难以规模化，且非同质化导致流动性不足。为解决这些问题，我们提出了一种高效的数字方法论，结合遥感数据、现代计量经济学技术以及链上认证与交易，创建了一种新型数字碳资产（PACT稳定币），碳抵消声明可通过其实现透明验证。PACT稳定币通过可复现的计算流水线产出，该流水线用于估算碳抵消项目的气候效益，不仅量化了涉及的二氧化碳排放量，还允许基于共生效益（如生物多样性和行政区域属性）对相似信用额度进行池化，从而通过池内的同质化提升流动性。我们在Tezos区块链上实施并评估了PACT碳稳定币，该区块链旨在促进低成本交易并最小化环境影响。我们的实现包括一个用于跟踪信用额度发行、所有权和注销的注册合约，以及一个桥接链上与链下交易的托管合约。通过提供透明、可扩展且高效的高完整性碳信用交易框架，我们的工作为自愿碳市场带来了规模与信任。