California air resources board forest carbon protocol invalidates offsets

Abstract

The commercial asset value of sequestered forest carbon is based on protocols employed globally; however, their scientific basis has not been validated. We review and analyze commercial forest carbon protocols, claimed to have reduced net greenhouse gas emissions, issued by the California Air Resources Board and validated by the Climate Action Reserve (CARB-CAR). CARB-CAR forest carbon offsets, based on forest mensuration and model simulation, are compared to a global database of directly measured forest carbon sequestration, or net ecosystem exchange (NEE) of forest CO2. NEE is a meteorologically based method integrating CO2 fluxes between the atmosphere, forest and soils and is independent of the CARB-CAR methodology. Annual carbon accounting results for CAR681 are compared with NEE for the Ameriflux site, Howland Forest Maine, USA, (Ho-1), the only site where both methods were applied contemporaneously, invalidating CARB-CAR protocol offsets. We then test the null hypothesis that CARB-CAR project population data fall within global NEE population values for natural and managed forests measured in the field; net annual gC m−2yr−1 are compared for both protocols. Irrespective of geography, biome and project type, the CARB-CAR population mean is significantly different from the NEE population mean at the 95% confidence interval, rejecting the null hypothesis. The CARB-CAR population exhibits standard deviation ∼5× that of known interannual NEE ranges, is overcrediting biased, incapable of detecting forest transition to net positive CO2 emissions, and exceeds the 5% CARB compliance limit for invalidation. Exclusion of CO2 efflux via soil and ecosystem respiration precludes a valid net carbon accounting result for CARB-CAR and related protocols, consistent with our findings. Protocol invalidation risk extends to vendors and policy platforms such as the United Nations Program on Reducing Emissions from Deforestation and Forest Degradation (REDD+) and the Paris Agreement. We suggest that CARB-CAR and related protocols include NEE methodology for commercial forest carbon offsets to standardize methods, ensure in situ molecular specificity, verify claims of carbon emission reduction and harmonize carbon protocols for voluntary and compliance markets worldwide.

Science to Commerce: A Commercial-Scale Protocol for Carbon Trading Applied to a 28-Year Record of Forest Carbon Monitoring at the Harvard Forest

“…A universal scientifically accepted methodology based on direct measurement of CO 2 flux (EC) and net carbon sequestration (NEE), applied to the US-Ha1 28-year record, establishes the foundation for verifiable commercial carbon products. Relying upon the NEE methodology, forest carbon protocols that exclude CO 2 data for R eco would result in a project error (1992 to 2019) of~466% given that R eco represents~45% of NEE and cannot be excluded from a full net forest carbon accounting for financial products and trading [4]. As a result, forest carbon model based determinations of sequestered carbon are likely more uncertain as proxy data cannot be validated without independent direct measurement [5].…”

“…We emphasize that existing forest carbon protocols require that each tCO 2 captured remains fixed in the trees or soil for at least 100 years fulfilling the arbitrary permanence requirement of non-CO 2 based protocols such as the CARB and Climate Action Reserve (CAR) [4,77,78]. According to CARB-CAR protocols, landowners who exit the project prior to 100 years must repay the value of all issued offsets in the cases of reforestation and avoided emissions, and pay an additional penalty in the case of improved forest management [7], making exits punitive and infeasible.…”

“…Furthermore, variance in the no exit case for US-Ha1 is higher than in exited projects ( Figure 2 and Table A1 from the Supplemental) emphasizing the variable nature of annual carbon sequestration even over long intervals [81] and the need for direct measurement to validate claims of annual net CO 2 emission reduction for carbon markets by ecosystems, and R eco as represented by isofluxes. This approach incentivizes many of the potential short projects that are outside any existing net forest carbon protocol because the 100-year required project term is a high barrier to entry for landowners reflected in CARB-CAR projects representing less than~0.2% of available US land [4,77]. Moreover, the implementation of AB398 imposes new changes in offset pricing including an arbitrary price ceiling of $65 per allowance, and requires at least 50% of projects to directly benefit the State of California implying a carve-out for projects that must originate in the state [82].…”

“…Forest carbon net ecosystem exchange (NEE) for US-Ha1 employing eddy covariance (EC) for direct in situ CO 2 measurement for research purposes has been reported [1][2][3][4][5][6]. An objective of this study focuses on the requirements for implementing and validating a commercial protocol for net forest carbon storage products suitable for financial market transactions, requirements that have not been elucidated.…”

“…In this study we describe the financialization process for NEE (gC m −2 year −1 ) forest products through a retrospective analysis of the longest running forest carbon EC platform in the world, the Harvard Forest, Petersham, MA, USA. Model based forest carbon protocols that exclude CO 2 measurement cannot support equivalent transactions or be subject to retrospective analysis and validation employing direct CO 2 measurement methods [4]. We analyze the temporal and spatial dimensions of the US-Ha1 Environmental Measurement Site NEE CO 2 flux partitioned into Gross Primary Productivity (GPP) and Ecosystem Respiration (R eco ) including extrapolation of US-Ha1 tower data to the Prospect Hill area (~1500 hectares (ha)), where the US-Ha1 EC tower is located, and to 40,468 ha, based solely on numerical projection, to illustrate potential project revenue with increasing land area.…”