Abstract

Here we describe a pilot wetland carbon project located 30 km west of New Orleans where measurements were taken in 2013 and 2018, and applied to a carbon offset methodology published by the American Carbon Registry (ACR). Baseline emissions were modeled using values derived from scientific literature, which resulted in a net sequestration rate of 16,527 t CO2-e (tons carbon dioxide equivalents) per year if wetland greenhouse gases (CH₄ & N₂O) were included (619,727 over the 40-year project duration), and 5,003 t CO2-e/yr if wetland greenhouse gases were conservatively omitted (200,143 t CO₂e over 40 years). Alternatively, a kriging exercise was carried out that modeled the tree and soil pools, resulting in higher net sequestration of 18,084 t CO2-e/yr with greenhouse gases (723,375 t CO2-e over 40 years), and 6,560 t CO2-e/yr if greenhouse gases were omitted (262,472 t CO2-e over 40 years). Unfortunately, the project was withdrawn, prohibiting the issuance and eventual transaction of carbon credits, due to very large uncertainty estimates mostly associated with methane and nitrous oxide emissions as well as the kriging approach since in situ sampling could not be carried out as required by the methodology. Next steps to increase the commercial viability of wetland carbon offsets include: closing knowledge gaps in wetland emissions of methane and nitrous oxide; developing means to reduce costs of monitoring, reporting and verification; fully accounting for prevented loss; developing remote sensing methods for monitoring and verification; and development of biogeochemical models to predict methane and nitrous oxide fluxes and sequestration pools. Though the project did not generate carbon credits, the results and lessons learned are intended to inform managers, and blue carbon project developers on how to develop wetland carbon credits that are high quality, economically competitive, and scientifically defensible.

摘要

在这里，我们描述了一个位于新奥尔良以西 30 公里处的试点湿地碳项目，该项目于 2013 年和 2018 年进行了测量，并应用于美国碳登记处 (ACR) 发布的碳抵消方法。使用来自科学文献的值对基线排放进行建模，如果包括湿地温室气体（CH ₄和 N ₂ O），则每年的净封存率为 16,527 吨 CO2-e（吨二氧化碳当量）（619,727 吨二氧化碳当量）。 40 年项目持续时间），如果保守地省略湿地温室气体排放量（200,143 t CO ₂e 40 岁以上）。或者，进行了模拟树木和土壤池的克里金法练习，导致温室气体净封存量更高，达到 18,084 吨 CO2-e/年（40 年内 723,375 吨 CO2-e）和 6,560 吨 CO2-e/年yr 如果省略温室气体（262,472 吨 CO2-e 超过 40 年）。不幸的是，该项目被撤回，禁止碳信用额的发行和最终交易，因为非常大的不确定性估计主要与甲烷和一氧化二氮排放以及原地克里金法有关无法按照方法学的要求进行抽样。提高湿地碳补偿商业可行性的下一步措施包括：缩小湿地甲烷和一氧化二氮排放方面的知识差距；开发降低监测、报告和核查成本的方法；充分考虑防止损失；开发用于监测和验证的遥感方法；开发生物地球化学模型以预测甲烷和一氧化二氮通量和封存池。尽管该项目没有产生碳信用额，但其结果和经验教训旨在告知管理者和蓝碳项目开发商如何开发高质量、具有经济竞争力和科学依据的湿地碳信用额。