Last month, the National Academies of Sciences, Engineering, and Medicine (NASEM) released a report on a relatively new field of research – atmospheric methane removal. Addressing methane is critically important in addressing climate change – methane is the second largest contributor to human-driven warming after carbon dioxide. Although the concentration of methane is much lower than carbon dioxide and remains in the atmosphere for less time, a ton of methane has 80 times the heat trapping potential of a ton of carbon dioxide over a 20 year period. As the NASEM report highlights, “rapid and sustained reductions in anthropogenic methane emissions are critical to limit warming in future decades.” However, rising human-driven methane emissions in recent years, coupled with concern about the risk of rising natural emissions in a warming world, have increased interest in exploring the feasibility of removing methane already in the atmosphere. This report represents a key milestone in the evaluation of whether atmospheric methane removal will be a viable and socially acceptable additional tool to help fight climate change.
The NASEM report calls for $50-80 million per year in research funding over the next 3-5 years. The funding would go towards better scientific understanding of methane sinks and sources and methane removal approaches. Crucially, the funding would also go towards social science, governance, and systems research – an acknowledgment from the NASEM committee that public engagement on emerging technologies, and whether we can govern them effectively, must be an integral part of assessing whether they should move forward.
As part of its report, NASEM commissioned a series of papers from outside experts. The Sabin Center contributed one of these papers on Legal Considerations for Atmospheric Methane Removal. Although the field is new, early investigation of legal frameworks, alongside other social science research, is essential to better inform decisions about whether and how the field should develop.
Background on Atmospheric Methane Removal
Methane concentrations in the atmosphere have grown 2.5 times their preindustrial average – to about 2 parts per million. Methane has contributed 0.5°C of the 1.1°C of current global warming. Human-driven sources of methane, including fossil fuels, agriculture, and waste, account for about 60% of emissions. Natural sources, most importantly wetlands, account for about 40%. While technologies exist to reduce emissions from fossil fuel sources cheaply and efficiently, agricultural emissions and natural emissions are often diffuse. This means they are emitted at low concentration, and existing technology cannot prevent the emissions at the source. This, coupled with concerns that climate change could unlock significant additional natural emissions from tropical wetlands and melting permafrost, has increased interest in atmospheric methane removal.
Atmospheric methane removal refers to human interventions to accelerate the conversion of methane in the atmosphere to a form that causes less warming, to physically remove methane from the atmosphere and store it elsewhere, or to increase the methane sink in ecosystems like forests or soils. The graphic and table below, from the NASEM report, represent five different approaches to atmospheric methane removal.
The five methane removal approach categories analyzed in the NASEM report differ across several dimensions, including associated costs and impacts. Two key distinctions are highly relevant to legal analysis of the approaches. First is whether they involve open or closed systems. Methane reactors and methane concentrators are partially closed systems – meaning that they are bounded by physical barriers where catalysts stay inside the barrier, whereas air and energy flow through the system. Surface treatments, ecosystem uptake enhancement, and atmospheric oxidation enhancement are open systems – meaning that they lack a physical boundary and activities occur in the open environment. Another key distinction between the approaches is in potential environmental impacts. For example, potential air pollution effects from atmospheric oxidation enhancement might differ from local ecosystem impacts from adding materials to soils as part of ecosystem uptake enhancement.
There are also key differences in technological readiness levels between different approaches, but all are in the very early stages of development and significant research is still needed to evaluate feasibility, scalability, net climate impact, social acceptability, and legal frameworks applicable to each. One technical challenge for each approach is the low concentration of methane in the atmosphere – about 2 parts per million – which is about 200 times lower than that of carbon dioxide.
Some Key Takeaways from the NASEM Report
- Rising methane concentrations in the atmosphere present significant near-term warming risks. Rapid and sustained reductions in human-driven methane emissions are critical to limit warming in future decades.
- Atmospheric methane removal technologies, even if successfully developed, will not replace emissions reductions on timescales relevant to limiting peak warming this century.
- Now is the time to invest in research into atmospheric methane removal. That’s because the approaches may be needed to address rising methane emissions, particularly the warming-induced rising natural emissions from wetlands and permafrost.
- Research is needed into atmospheric and ecosystem methane sinks in order to better understand the potential to enhance those sinks, determine how much removal is needed, and determine how to monitor and verify the removal.
- Foundational research into atmospheric methane removal approaches is needed to increase a currently “very limited” knowledge base. The committee noted that all research questions at this stage “can be assessed without requiring deployment” of the technologies, but noted that “technology research may require thoughtful demonstration efforts.” The committee later clarified that the definition of research projects, and how these are differentiated from demonstration and deployment, are key questions that need to be answered.
- Foundational research is needed across social and policy dimensions of methane removal in order to better understand how research would affect or be affected by the public.
- Establishing early governance of atmospheric methane removal research is important to facilitate research that enhances benefits, minimizes costs, and justly distributes benefits across populations.
- Research should move forward in two phases. In the first phase, $50 million–80 million per year over 3-5 years should be invested in some of the key foundational research areas described above. After 3-5 years, a second phase may be required to advance further research and assessment.
Legal Considerations for Atmospheric Methane Removal
As mentioned above, the NASEM committee commissioned the Sabin Center to analyze legal considerations surrounding atmospheric methane removal. Our paper found that while there is no specific legal framework governing atmospheric methane removal, a variety of general environmental and other U.S. and international laws may apply to field research and deployment. The applicability of different laws will depend on a range of factors, including the specific nature of the activities (e.g., whether they involve open or closed systems), the purpose for which they are conducted (e.g., whether they involve research or commercial activities), where they take place (e.g., on land or in the ocean), and the nature and location of their impacts.
The paper analyzes applicable international law, including both customary international law and international agreements. Of particular relevance are a series of decisions governing ocean fertilization and geoengineering adopted by parties to the Convention on Biological Diversity, London Convention, and London Protocol, which can shed light on the way international legal institutions and individual countries might be expected to treat atmospheric methane removal activities.
The paper also analyzes domestic U.S. law. Atmospheric methane removal activities will need to comply with a variety of federal environmental laws, in addition to any tribal, state, and local laws applicable to a given project. This patchwork approach to regulating atmospheric methane removal projects is likely to result in significant uncertainties and complexities for project developers. Legal reforms may, therefore, be useful or necessary to ensure efficient, safe, and responsible atmospheric methane removal research and deployment (if the latter is deemed appropriate).
The NASEM report is available here.
The commissioned paper on legal considerations for atmospheric methane removal is available here.
The Sabin Center previously published a report analyzing the legal framework applicable to one atmospheric methane removal approach, atmospheric oxidation enhancement, which is available here.
Korey is the senior fellow in carbon management and negative emissions at the Sabin Center for Climate Change Law
