Adaptive Autonomous Underwater Sampling for Marine Carbon Dioxide Removal Verification
Closing the Onboard Decision Loop on the Cost Line That Is Blocking Credit Issuance
Hass Dhia — Smart Technology Investments Research Institute
Market opportunity analysis for autonomous underwater vehicles that decide where to sample next while tracking an alkalinity plume, rather than flying pre-planned transects. Buyers have contracted 578,000 tonnes of marine carbon dioxide removal, and 0.3% of that volume has been formally issued as credits (AlliedOffsets, October 2025). The bottleneck is in-water verification. A WHOI-led field study measured an alkalinity patch travelling 14.8 km in 36 hours while a research vessel sampled it once every 1,200 metres, capturing only 10% of the intended carbon uptake before the campaign ended (Subhas et al., Biogeosciences, 2025); its authors name the ability to track the intervention through space and time as the central challenge of in-water MRV. Both halves of the solution are separately validated: lab-on-chip alkalinity sensors have flown on a long-range AUV in the Celtic Sea to better than 5 micromoles per kilogram, and long-range AUVs have autonomously tracked a chlorophyll feature for four days without surfacing. Nothing joins them. ARPA-E's $36 million SEA-CO2 portfolio funded eleven projects, every one a sensor or a model, and none the decision layer in between.















