Spatial Tradeoffs and Prioritization for Ocean Alkalinity Enhancement Deployment

Abstract

Marine carbon dioxide removal (mCDR) is increasingly discussed as a complement to emissions reduction, but the conditions under which it could be deployed at meaningful scale remain poorly resolved. Ocean alkalinity enhancement (OAE) has attracted particular attention because of its large theoretical storage potential, relatively durable carbon sequestration, and growing body of modeling and experimental work. Yet suitability for OAE cannot be assessed on carbon uptake efficiency alone. Potential deployment areas are already embedded within crowded marine spaces shaped by human use including – but not limited to – fishing effort, shipping density, coastal management regimes, and emerging governance requirements. This paper employs a spatial tradeoff framework for evaluating where high-efficiency OAE conditions coincide with other competing, or complementary, ocean uses. Using a public OAE efficiency atlas as the core efficacy layer, the analysis overlays cells with processed ocean use data at a comparable spatial resolution. The paper asks one primary question: what levels of existing ocean use occur within the most favorable modeled OAE areas? Rather than treating suitability as a purely biogeochemical problem, the study reframes deployment as a marine spatial planning question in which efficacy and conflict or complement with existing uses must be evaluated together. The resulting approach is intended as a pragmatic first step toward more policy-relevant prioritization exercises, including future optimization analyses that seek to meet carbon-removal targets while minimizing impact on other ocean uses. In doing so, the project contributes an environmental management perspective to the mCDR literature by linking emerging OAE science to ocean-use compatibility and governance.