A framework for assessing atmospheric oxidation enhancement approaches

Atmospheric oxidation enhancement (AOE) is a proposed category of methane removal that involves dispersing oxidizing agents to accelerate the natural oxidation of atmospheric methane. There is currently a lack of standardized metrics for assessing and comparing proposed AOE approaches. We present a quantitative assessment framework centered on conversion efficiency—the ratio of oxidized methane mass to dispersed material mass—to evaluate the feasibility of AOE approaches.

We propose two necessary but insufficient criteria: (1) climate beneficial (net carbon negative in CO₂e, accounting for methane oxidation and emissions from material production/transport), and (2) cost-effectiveness (cheaper than the social cost of methane, currently estimated to be ~$2000/tCH₄). These thresholds define minimum conversion efficiency requirements for each approach. 

We apply this framework to two case studies: (1) iron salt aerosols (ISA), 40% FeCl₃ dispersed from marine vessels, and (2) hydrogen peroxide, 50% H₂O₂ dispersed from land-based towers. Drawing on published atmospheric modeling results and assumptions for material production costs and carbon intensities, we evaluate the conversion efficiencies that would be required to meet the climate beneficial and cost-effective criteria.

Conversion efficiency varies by location for both ISA and H₂O₂, with some deployment scenarios being climate detrimental. Critical uncertainties include regional variations in OH and Cl recycling rates and poorly constrained atmospheric loss pathways—uncertainties that could shift the conversion efficiency by orders of magnitude.

This proposed framework enables standardized comparisons and identifies priority research questions. Approaches failing to meet these criteria under optimistic assumptions suggest resources may be better allocated elsewhere, while those showing potential under plausible conditions merit deeper investigation. The goal is to provide a shared analytical foundation to help the community efficiently navigate the expanding solution space for atmospheric oxidation enhancement.