Methane Removal FAQs — Spark Climate Solutions

What is methane removal?

Methane removal is an emerging climate field that explores whether there are ways to break down methane once it is already in the atmosphere faster than existing natural systems would on their own to further mitigate climate change.

Why might methane removal be a helpful climate solution?

Methane is a powerful greenhouse gas that plays an outsized role in near-term warming. Natural systems are an important source of this gas, and evidence indicates that these sources may be amplified in a warming world and emit even more. Even if we succeed in reducing anthropogenic emissions of methane, we “cannot ignore the possibility of accelerated methane release from natural systems, such as widespread permafrost thaw or release of methane hydrates from coastal systems in the Arctic.” (Jackson 2021)

Methane removal could potentially play two important roles: (1) serving as a potential partial response to such methane-emitting natural feedback loops and tipping elements to reduce how much these systems further accelerate warming, and (2) addressing residual atmospheric methane in order to reduce near-term warming, lower peak temperature, and reduce natural feedback and tipping element risk.

Can methane removal be used in place of methane emissions reduction?

No. Aggressive emissions reductions—for all greenhouse gases, including methane—are the highest priority. Methane removal cannot be used in place of methane emissions reduction. It’s incredibly urgent and important that methane emissions be reduced to the greatest extent possible, and that further innovation to develop additional methane abatement approaches is accelerated.

What’s the current state of methane removal?

There are several potential approaches to accelerate the breakdown of atmospheric methane. All of these are in early research or idea stages. In each case, fundamental questions remain about their feasibility, scalability, and side effects. Research funding is a bottleneck for much of the field.

Is large-scale methane removal possible?

More research is needed to determine the viability and safety of large-scale methane removal. The current state of knowledge indicates several approaches may have the potential to remove >10 Mt of methane per year (~0.8 Gt CO₂ equivalent over a 20 year period), but the research is too early to verify feasibility, safety, and effectiveness. Methane has certain characteristics that suggest that large-scale and cost-effective removal could be possible, including favorable energy dynamics in turning it into CO₂ and the lack of a need for storage.

How much methane removal do we need?

The volume of methane removal “needed” will depend on our overall climate trajectory, atmospheric methane levels as influenced by anthropogenic emissions and anthropogenically amplified natural systems feedbacks, and target global temperatures. Some evidence indicates we may have already passed warming thresholds that trigger natural system feedbacks with increasing methane emissions (Peng 2022). Depending on the ultimate extent of warming, permafrost methane release and enhanced methane emissions from wetland systems are estimated to potentially lead to ~40-200 Mt/yr of additional methane emissions and a further rise in global average temperatures (Zhang 2023, Kleinen 2021, Walter 2018, Turetsky 2020). Methane removal may prove to be the primary strategy to address these emissions.

Is methane removal permanent?

Methane removal permanently removes methane from the atmosphere. Most methane removal methods being researched oxidize, or break down, methane into carbon dioxide, water, and other byproducts, or if biological processes are used, consumed to produce new biomass. These products and byproducts will remain cycling through their respective systems, but without the more potent warming impact of methane.

The carbon dioxidethat remains following oxidation will still cause warming, but this is no different than what happens to the carbon in methane through natural removal processes. Methane removal approaches accelerate this process of turning the more potent greenhouse gas methane into the less potent greenhouse gas carbon dioxide, permanently removing the methane to reduce warming.

How much does methane removal cost?

The cost of methane removal will depend on the specific potential approach and further innovation, specific costs are not yet known at this stage. Some approaches have easier paths to cost plausibility, while others will require significant increases in catalytic, thermal or air processing efficiency to achieve cost plausibility. More research is needed to determine credible estimates, and innovation has the potential to significantly lower costs.

How does methane removal interact with other strategies to tackle the climate crisis?

Tackling the climate crisis will require a full portfolio of solutions, and methane removal is not a replacement for anything else. We need to scale up methane emissions reduction strategies that we already know, pursue R&D into additional strategies for emissions sources that we don’t know how to reduce, and explore methane removal as one way to manage growing risks from elevated natural emissions. These strategies collectively can address the full range of methane-induced climate risks.

Why don't we just reduce methane emissions versus developing methane removal?

Reducing methane emissions will be critical to addressing climate change, and the development of methane removal cannot displace this important work. Recent scientific evidence indicates that methane emissions may also increase in the coming years from natural systems like wetlands and permafrost, and because these emissions cannot be addressed with traditional emissions reduction measures there is reason to believe methane removal may serve as an important climate risk reduction strategy.

Can methane removal be used in place of carbon dioxide removal?

Greenhouse gases are not interchangeable. Methane removal cannot be used in place of carbon dioxide removal because it cannot address historical carbon dioxide emissions, manage long-term warming or counteract other effects (e.g., ocean acidification) that are results of humanity’s carbon dioxide emissions.

How is methane removed from the atmosphere today? What are the natural methane sinks?

Methane has a short atmospheric lifetime due to substantial methane sinks. The primary methane sink is atmospheric oxidation, from hydroxyl radicals (~90% of the total sink) and chlorine radicals (0-5% of the total sink). The rest is consumed by methane-oxidizing bacteria and archaea in soils (~5%). While understood at a high level, there is substantial uncertainty in the strength of the sinks and their dynamics.

Methane isn’t captured from the atmosphere and stored, like it is for carbon dioxide, but “broken down.” When methane breaks down in the atmosphere, it also produces additional climate forcers, including tropospheric ozone, carbon dioxide, and stratospheric water, which contribute to its overall impact. These oxidation processes, even including the other effects, are all highly climate beneficial because of methane’s high GWP.

Why would we want to oxidize methane if it only turns into carbon dioxide, another greenhouse gas?

Methane is a potent greenhouse gas, 43 times stronger than carbon dioxide molecule for molecule, with an atmospheric lifetime of roughly a decade (IPCC, calculation from Table 7.15). Existing methane sinks convert the carbon in methane to carbon dioxide, methane removal approaches would be accelerating this process to shorten the time period for which the carbon is in the more potent form of methane.

What are the drivers of the current rise in atmospheric methane levels?

Up until about 2000, the growth of methane was clearly driven by growing human-caused emissions from fossil fuels, agriculture, and waste. But starting in the mid-2000s, after a brief pause where global emissions were balanced by sinks, the level of methane in the atmosphere started growing again. At the same time, atmospheric measurements detected an isotopic signal that the new growth in methane may be from recent biological—as opposed to older fossil—origin. Multiple hypotheses exist for what the drivers might be, though the answer is almost certainly some combination of these. Hypotheses include changes in global food systems, growth of wetlands emissions as a result of the changing climate, a reduction in the rate of methane breakdown and/or the growth of fracking. Learn more in our blog post.

Methane’s atmospheric lifetime is only 9-12 years. Why would we need to remove it when it’s going to remove itself soon anyway?

Methane has a significant warming effect for the 9-12 years that it remains in the atmosphere. Given how potent methane is, and how much is currently being emitted, even with a short atmospheric lifetime, methane is accumulating in the atmosphere and the overall warming impact of current and recent methane emissions is 0.5°C. Methane removal approaches may someday be able to bring methane-driven warming down faster than with natural sinks alone. The significant risk of ongoing substantial methane sources, such as natural methane emissions from permafrost and wetlands, would lead to further accumulation. Exploring options to remove atmospheric methane is one strategy to better manage this risk.

Can the same problems that methane removal potentially solve already be solved by carbon dioxide removal?

Carbon dioxide removal will play an important role in managing climate risk, addressing historical emissions, limiting long-term warming, and decreasing ocean acidification. Most potential ethane removal approaches are independent from carbon dioxide removal approaches, and would provide additional tools to further mitigate warming, and address methane-specific risks. Some methane removal approaches have characteristics that suggest that they may be able to get to scale quickly once developed and validated, should deployment be deemed appropriate, which could augment our near-term warming mitigation capacity on top of what carbon dioxide removal and emissions reductions offer.

When will these approaches be available?

Research into all methane removal approaches is just beginning, and there is no known timeline for their development or guarantee that they will prove to be viable and safe.

How big is the methane removal research field?

The methane removal research field is just beginning and has a lot of room to grow. For a better sense of the size of the field, read more here about the positive scientific community response to Spark’s first round of exploratory grants for atmospheric methane research.

How can we ensure methane removal is done responsibly and safely?

All methane removal approaches must be carefully researched to determine their feasibility, scalability, and side effects. Robust public research programs are an important first step in making sure that methane removal is done responsibly. Any field testing, or potential future deployment of a proposed solution must be supported by rigorous research into social and environmental impacts, including unintended consequences, and effective governance will need to prioritize the public interest and ensure transparency and accountability.

What do we need next for methane removal?

Methane removal stands to benefit most from public funding advocacy and engagement, scientific field-building and early philanthropic funding targeted towards the establishment of integrated research programs to develop and evaluate critical new approaches. Researchers and supporters must also ensure that methane removal always increases our overall climate mitigation ambition.

How could methane removal be paired with carbon dioxide removal? Could we just add methane sorbents or solvents to direct air capture systems?

Some methane removal and carbon dioxide removal approaches overlap. Some soil amendments may have an impact on both methane and carbon dioxide removal, and are currently being researched. Catalytic methane-oxidizing processes could be added to direct air capture (DAC) systems for carbon dioxide, but more innovation will be needed to make these systems sufficiently efficient to be feasible. If all planned DAC capacity also removed methane, it would make a meaningful difference, but still fall very short of the scale of methane removal that could be needed to address rising natural methane emissions, and additional approaches should be researched in parallel.

How much overlap is there between methane removal approaches and mitigation options, for example around landfills, rice paddies and dairy barns?

Methane emissions destruction refers to the oxidation of methane from higher-methane-concentration air streams from sources, for example air in dairy barns. There is technical overlap between some methane emissions destruction and methane removal approaches, but each area has its own set of constraints that will also lead to non-overlapping approaches, given different methane concentrations to treat, and different form-factor constraints.

What kind of approaches are being explored for methane removal?

Several approaches are being considered for methane removal:

Breakdown reactors: Closed systems that process large volumes of air to oxidize methane using a biological or catalytic process. Catalytic processes may use energy from the sun, artificial light, or heat.
Surface treatments: Coating panels, rooftops or other large surfaces with catalysts that oxidize methane using sunlight.
Methanotrophy enhancement: Accelerating the activity of methane-consuming bacteria and archaea (for example, methanotrophic soil bacteria).

Atmospheric oxidation enhancement: Enhancing the reactive oxidation of methane in the atmosphere by generating or introducing airborne materials, like chlorine and hydroxyl radicals.

Why pursue strategies to oxidize (break down) atmospheric methane instead of adsorbing, separating, or concentrating the methane as is done with carbon dioxide?

Given methane’s dilution in the atmosphere (roughly 2 parts per million), current literature suggests that its oxidation would likely be more efficient than approaches that first require adsorption, separation, or concentration. This is a relatively early field, and researchers are considering various ideas for further exploration in this area.

Atmospheric Methane Removal

Methane Removal Frequently Asked Questions

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