Why is monitoring marine carbon removal so hard?
The ocean is not a bathtub — it's a highly variable, strongly advective system where carbon and tracers can be rapidly redistributed across space, depth, and even national boundaries [4]. This means that if you add alkalinity or stimulate a phytoplankton bloom to pull CO₂ out of the atmosphere, you cannot simply measure the carbon at the deployment site and call it done. The carbon can move elsewhere, making it extremely difficult to prove that the removal actually happened and that it will stay stored for centuries. As [2] puts it, there are 'significant knowledge gaps and challenges, particularly in monitoring, reporting, and verification' for marine carbon dioxide removal (mCDR).
To address this, [4] proposes a six-pillar MRV framework covering baselines, additionality, detection and attribution, durability, non-CO₂ greenhouse gases, and environmental indicators. But even this framework acknowledges that current observing systems are insufficient — they recommend integrating in situ observations, autonomous platforms, and Earth system modeling, and they explicitly state that scaling should be limited 'until MRV protocols are demonstrated.' In other words, the monitoring challenge is so fundamental that it should constrain how fast we deploy these technologies.
What about land-based durable removal — is it any easier?
Not really. In the Arctic, permafrost dynamics, hydrology, and ecological sensitivity create 'considerable uncertainty and context-dependent trade-offs' for every CDR method examined [1]. Peatland restoration and blue carbon protection are the most immediately actionable options, but even they face major monitoring hurdles because thawing permafrost can release stored carbon, potentially offsetting any removal. The paper concludes that 'none currently demonstrates unequivocal feasibility at scale under Arctic conditions,' and that governance fragmentation and geopolitical tensions add further complications.
For enhanced weathering (spreading crushed silicate rock on soils to accelerate natural CO₂ uptake), the monitoring challenge is equally daunting. As [3] explains, this is an 'open-system pathway' — the carbon is ultimately stored in the oceans, with potential losses occurring during transfer from soil to ocean. Measuring the weathering rate in the field requires combining solid-phase measurements (analyzing the rock and soil minerals), aqueous-phase measurements (analyzing water chemistry), and gas-phase measurements (tracking CO₂ fluxes). Each method has strengths and limitations, and the paper stresses that 'surplus measurement strategies and well-designed experiments' are critical because the industry is still in its early stages. So no, land-based methods are not a simple fix for the monitoring problem.
What does this mean for the future of durable CDR?
The papers converge on a clear message: monitoring challenges are not a minor technical detail — they are a core barrier to scaling durable carbon removal. [5] emphasizes that governance frameworks are 'fragmented and fall short in adequately regulating the approaches under development,' and that research on monitoring, reporting, and verification must be a top priority. [4] goes further, recommending 'clear limits on scaling or co-deployment until MRV protocols are demonstrated.'
All five papers agree that rapid emissions reductions must remain the top priority, and that CDR should not be used as an excuse to delay decarbonization. The monitoring challenges are real, they are being underestimated, and they demand a much more cautious, well-funded, and internationally coordinated approach than current efforts reflect.
About These Sources
This answer is built on 5 peer-reviewed studies — published from 2024 to 2026, 5 from 2024 or later, 1 in Q1 journals — selected as the most relevant from 5 studies that passed quality screening, drawn from 51 papers retrieved from a database of over 500 million.
Sources used in this answer
Is carbon dioxide removal in the Arctic region really feasible?
In a synthesis of evidence on Arctic CDR, none of the methods examined (peatland restoration, blue carbon, afforestation, enhanced weathering, ocean alkalinity enhancement, direct air capture) demonstrate unequivocal feasibility at scale, with feasibility constrained by permafrost dynamics, hydrology, ecological sensitivity, and governance fragmentation.
Marine carbon dioxide removal may be a future climate solution
This review of marine CDR finds that while abiotic approaches (e.g., ocean alkalinity enhancement) offer higher sequestration potential and longer-term storage than biotic methods, significant knowledge gaps remain in monitoring, reporting, and verification.
A review of measurement for quantification of carbon dioxide removal by enhanced weathering in soil
This review of measurement methods for enhanced weathering in soils concludes that the open-system nature of the pathway makes monitoring challenging, requiring surplus measurement strategies combining solid, aqueous, and gas-phase analyses, and that the industry is still in its early stages.
Advancing Monitoring Reporting and Verification for marine Carbon Dioxide Removal
This synthesis on MRV for marine CDR identifies a fundamental challenge: the ocean's high variability and strong advection mean carbon and tracers can be rapidly redistributed, and it recommends a six-pillar MRV framework with clear limits on scaling until protocols are demonstrated.
Challenges and opportunities for marine carbon dioxide removal (mCDR)
This review of marine CDR finds that governance frameworks are fragmented and inadequate, and recommends prioritizing decarbonization over CDR deployment, strengthening MRV research, and harmonizing governance through international bodies like the London Convention and UNFCCC.