From flux tower to carbon credit – strengths, weaknesses, opportunities, threats

Background/Question/Methods

At the 2021 Glasgow Climate Summit, the US committed to reducing its net greenhouse gas emissions to 50% below 2005 levels by 2030. In addition to decarbonizing the US economy, two principal carbon sequestration categories are envisioned for implementing this commitment: intensive abiotic sequestration such as Carbon Capture and Storage (CCS) and extensive biotic sequestration such as Nature-based Climate Solutions (NbCS). Measuring, reporting and verifying (MRV) the true climate benefits of these mitigation approaches are essential challenges that require balancing robustness and feasibility. Here, we explore a dialogue between academia and industry in pursuit of appropriately balanced MRV depending on mitigation project category, scale, policy requirements, and the acceptable level of uncertainty. Eddy-covariance flux towers provide one of the few methods for direct observations of net carbon, water, and heat exchanges between the earth’s surface and its atmosphere. This has led to their acceptance as the de facto gold-standard for basic research in hectare-scale urban and natural settings, such as at National Ecological Observatory Network sites. However, the rich information provided by flux towers is rarely applied to market-ready MRV, owing to cost of implementation and complexity of data interpretation.

Results/Conclusions

Here, we present progress towards a turnkey Emissions Observation and Data Analysis System (EODAS) that overcomes those challenges by integrating flux towers with simultaneously available ground-based, airborne and spaceborne observations. This approach aims to harness the benefits and overcome the limitations of each individual observational asset. Flux tower EODAS produces carbon, water and heat flux maps at half-hourly and decameter resolutions over 1 km2 - 100 km2 mitigation project domains. The near-real time spatialization enables continuous MRV, precise problem tracking and resolution for underperforming locations, and ultimately provides robust information for mitigation action. An initial sensitivity study shows that flux tower EODAS can reduce the MRV cost per unit area by at least one order of magnitude compared to current industry practices. Implementing such cost savings can increase the accessibility and economic attractiveness of carbon sequestration, and accelerate widespread adoption. We expect to further specify Strengths, Weaknesses, Opportunities and Threats (SWOT) from applying EODAS to the CHEESEHEAD19 (https://doi.org/10.1175/BAMS-D-19-0346.1) 100 km2 high-density dataset. Key applications include: industry leak detection such as for CCUS; NbCS and precision agriculture; biophysical and permafrost feedbacks; emissions inventory validation and urban air quality.