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 and offsets, 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 protocol annual offsets, resulting from forest mensuration and growth simulation models, are compared with a population of forest field sites for which annual net ecosystem exchange (NEE) of carbon was measured directly as flux by CO2 eddy covariance, a meteorologically based method integrating forest carbon pools. We characterize differences between the protocols by testing the null hypothesis that the CARB-CAR commercial annual offset data fall within the boundaries of directly measured forest carbon NEE; gC m-2yr-1 are compared for both datasets. Irrespective of geographic location and project type, the CARB-CAR population annual mean value is significantly different from the NEE population mean at the 95% confidence interval, rejecting the null hypothesis. The CARB-CAR population exhibits standard deviation ~5x that of the NEE natural ranges; the variance exceeds the 5% compliance limit for invalidation of CARB-CAR offsets. Exclusion of the soil carbon pool typical for CARB-CAR net carbon budgets pose insuperable carbon accounting uncertainty for offsets that extend to vendor platforms and policies including the United Nations Program on Reducing Emissions from Deforestation and Forest Degradation and the Paris Agreement. NEE methodology for commercial forest carbon offsets ensures in situ molecular specificity, verification of claims for net carbon balance, performance-based pricing and harmonization of carbon protocols for voluntary and compliance markets worldwide, in contrast to continuing uncertainty posed by traditional estimation-based forest carbon protocols.

Multi‐Decadal Carbon Cycle Measurements Indicate Resistance to External Drivers of Change at the Howland Forest AmeriFlux Site

“…This applies especially with assessing hard‐to‐observe carbon pools such as soils, important non‐CO 2 greenhouse gas fluxes, and changes in ecosystem energy balance (Hemes et al., 2021). Based on our own experiences, however, we are more cautious about the use of eddy flux methods for commercial‐scale accounting of forest C storage, especially in lieu of inventory data (e.g., Bautista et al., 2021; Marino et al., 2019). Marino et al.…”

“…Marino et al. (2019) argued that a greater than 10‐fold disparity between Howland eddy flux results and inventory data collected to register the Howland Forest as a Climate Action Reserve under the California Air Resources Board (CARB) should invalidate the approach of the registry. However, the difference exists because credit was given for initial standing live carbon stocks at Howland that greatly exceeded the average standing live carbon stocks on similar lands within the region (Section 6.2.1, Compliance Offset Protocols U.S. Forest Projects, https://www.arb.ca.gov/regact/2010/capandtrade10/copusforest.pdf).…”

Linking the EU ETS with California’s Cap-and-Trade Program

“…These projects may even provide perverse economic incentives for the perpetuation of coal mining and for switching from crop to rice production, which could lead to increased GHG emissions in the long run. Moreover, evidence suggests that the current design of MRV methodologies for California's forest carbon offsets cannot sufficiently prevent over-crediting (Marino et al 2019).…”

“…To that end, certain improvements to California's MRV framework for offsets can enhance its acceptability by the EU and, simultaneously, augment its environmental stringency. For instance, CARB has been advised to update and strengthen the methodology for calculating emissions reductions from forest offset programs (Marino et al 2019). The Californian authorities should also assess and mitigate the risk of perverse incentives within eligible project types, as well as consider reinforcing the assessment of project additionality, narrowing down project eligibility criteria and conducting systematic analyses to diminish the risk of overcrediting (Haya et al 2020).…”