From Whack-a-Mole to a Metabolic Overhaul: A New Framework for Climate Action

For years, my role as a corporate sustainability director felt like a high-stakes game of whack-a-mole.

We would identify an emission source, invest millions in a technological fix, and celebrate a narrow victory, only to find that our solution had created new, often unforeseen, problems elsewhere.

The breaking point came with a state-of-the-art nitrous oxide (N2​O) abatement system we installed at a chemical plant.

It worked, slashing our N2​O emissions from that specific process vent.

But the victory was hollow.

The system was incredibly energy-intensive, driving up our electricity consumption and, with it, our carbon dioxide (CO2​) emissions.

Worse, the proprietary catalyst it used had a complex supply chain with a significant footprint of fluorinated gases (F-gases).

We had plugged one leak only to spring two more.

This costly failure was a profound lesson: tackling greenhouse gases (GHGs) one by one, as isolated problems, was a losing strategy.

The epiphany arrived not in an engineering manual, but in a book on urban planning.

It described the concept of a city’s “metabolic system”—the complex web of flows that brings in energy, water, and resources, and sends out products, services, and waste.

A healthy, sustainable city doesn’t just treat its pollution with end-of-pipe filters; it redesignes its metabolism for efficiency and circularity, turning waste streams into value streams.

This was the paradigm shift I needed.

I began to see our global industrial and agricultural systems not as a collection of discrete emission sources, but as a single, interconnected Global Metabolism.

Within this framework, each greenhouse gas is not a unique villain but a symptom of a specific metabolic disorder:

• Carbon Dioxide (CO2​) is the primary exhaust of an inefficient and linear Energy Metabolism, built on the one-way combustion of fossil fuels.
• Methane (CH4​) is the gaseous byproduct of an incomplete Waste Metabolism, representing undigested organic matter and fugitive, uncaptured energy.
• Nitrous Oxide (N2​O) is a sign of an imbalanced Nutrient Metabolism, a system overloaded with reactive nitrogen that it cannot fully process.
• Fluorinated Gases (F-gases) are potent Synthetic Toxins we have deliberately introduced, which the system has no natural way to break down.

This report is structured around this metabolic framework.

It moves beyond a simple list of fixes to present a systemic diagnosis and a series of integrated cures.

The urgency for this new approach is undeniable.

The Intergovernmental Panel on Climate Change (IPCC) in its Sixth Assessment Report (AR6) states with unequivocal certainty that human activities have already warmed the planet to 1.1°C above pre-industrial levels, spurring unprecedented changes to our climate system.¹

To have a chance of limiting this warming to the critical threshold of 1.5°C, global GHG emissions must peak before 2025 and be reduced by 43% by 2030.⁴

To understand the strategies that follow, it is essential to grasp the concept of Global Warming Potential (GWP), a metric used to compare the warming impact of different gases relative to CO2​ over a specific timeframe, typically 100 years.⁵

As the foundational reference table below illustrates, gases like methane, nitrous oxide, and F-gases have dramatically higher GWPs than

CO2​, making their mitigation a critical part of any effective climate strategy.

By reframing our approach from treating symptoms to healing the underlying metabolic systems, we can move beyond the frustrating game of whack-a-mole and begin building a truly sustainable and resilient global economy.

---

Table 1: Characteristics of Major Anthropogenic Greenhouse Gases

Greenhouse Gas	Primary Anthropogenic Sources	Atmospheric Lifetime	100-Year Global Warming Potential (GWP)
Carbon Dioxide (CO2​)	Fossil fuel combustion, deforestation, cement production	Variable (hundreds to thousands of years)*	1
Methane (CH4​)	Agriculture (livestock, rice), fossil fuel extraction, landfills	11.8 years	27–29.8
Nitrous Oxide (N2​O)	Agricultural soils (fertilizer), industrial processes, fossil fuel combustion	109 years	273
Sulfur Hexafluoride (SF6​)	Electrical transmission equipment, industrial processes	3,200 years	25,200
Hydrofluorocarbons (HFCs)	Refrigerants, air conditioning, aerosols, foam blowing	A few weeks to 270 years	Varies (up to 12,400)
Perfluorocarbons (PFCs)	Aluminum production, semiconductor manufacturing	2,600–50,000 years	Varies (up to 11,100)

Source: Data compiled from the U.S. Environmental Protection Agency.⁶

Note: The lifetime of

CO2​ is complex as it moves between the atmosphere, ocean, and land systems; a portion remains in the atmosphere for thousands of years.

---

Part I. Mitigating Carbon Dioxide (CO2​): Overhauling Our Energy Metabolism

Carbon dioxide is the most abundant anthropogenic greenhouse gas, accounting for approximately 79% of U.S. and 75% of global emissions.⁶

It is the defining signature of our global energy metabolism, a system fundamentally reliant on the linear process of extracting and burning fossil fuels for energy.

The largest single source of global GHG emissions is the burning of coal, natural gas, and oil for electricity and heat, which accounted for 34% of emissions in 2019.⁸

To mitigate

CO2​ emissions is to fundamentally re-engineer this metabolic pathway, shifting from a wasteful, extractive model to a clean, efficient, and circular one.

This requires a three-pronged strategy: detoxifying the energy supply, radically improving end-use efficiency, and actively cleaning up legacy pollution from the atmosphere.

Measure 1.1: Decarbonizing Power and Heat Generation

The most critical intervention in our energy metabolism is to change the fuel source itself.

This involves a systemic transition away from fossil fuel combustion and toward renewable energy sources like solar, wind, geothermal, and hydropower.⁹

For individuals and businesses, this can mean asking utility companies to switch to renewable energy plans or installing on-site generation like rooftop solar panels.⁹

At a national and global scale, it requires massive investment in utility-scale wind and solar farms, modernizing grid infrastructure to handle variable generation, and phasing out coal- and gas-fired power plants.

In 2022, 60% of U.S. electricity still came from burning fossil fuels, highlighting the scale of the challenge and the opportunity.¹²

A deeper analysis reveals that decarbonizing the electrical grid is not merely one mitigation option among many; it is the foundational prerequisite that unlocks the full decarbonization potential of other major sectors.

The push to electrify transportation by switching to electric vehicles (EVs) and to electrify industrial processes are central pillars of climate strategy.⁹

However, the ultimate climate benefit of these actions is entirely dependent on the carbon intensity of the electricity used.

An EV charged on a grid powered by coal merely shifts emissions from the tailpipe to the smokestack, offering localized air quality improvements but minimal net climate benefit.⁹

Similarly, the IPCC’s assessment of industrial mitigation highlights electrification as a key option, but only when “in combination with low-emission energy sources”.⁴

Therefore, cleaning the grid acts as a keystone strategy.

It transforms electrification from a simple fuel-switching exercise into a true decarbonization pathway, enabling systemic emissions reductions across the transportation and industrial sectors and multiplying the impact of every subsequent efficiency and electrification measure.

Measure 1.2: Enhancing End-Use Efficiency and Electrification

While decarbonizing the supply is paramount, reducing the metabolic demand for energy is equally crucial.

This involves two complementary actions: using less energy to perform the same task (efficiency) and shifting end-use technologies from direct fossil fuel combustion to electricity (electrification), which is then powered by an increasingly clean grid.

In the residential and commercial sectors, this strategy includes a suite of proven measures.

Conducting a professional home energy audit can identify key areas for improvement, such as sealing air leaks and adding insulation, which can significantly reduce heating and cooling loads.¹⁰

Switching from incandescent bulbs to LEDs can reduce lighting energy use by up to 85%.¹⁴

Upgrading to modern, energy-efficient appliances and replacing fossil fuel furnaces with electric heat pumps can further slash a building’s carbon footprint, with a heat pump conversion alone capable of reducing emissions by up to 900 kilograms of

CO2​ equivalent (CO2​e) per year.⁹

In the transportation sector, which is the largest source of direct GHG emissions in the United States, the strategy involves a shift away from petroleum-based fuels that power over 94% of transport.¹²

This includes transitioning to more fuel-efficient or hybrid vehicles and, most impactfully, to fully electric vehicles, a switch that can reduce an individual’s carbon footprint by up to 2 tons of

CO2​e annually.⁹

Critically, it also involves reducing vehicle miles traveled altogether by promoting active transport like walking and cycling and investing in robust public transit systems.⁹

It is a strategic error to frame these efficiency measures solely as climate solutions, as this understates their value and limits their political and social appeal.

A more powerful and accurate framing presents energy efficiency as a multi-faceted policy for economic stimulus, public health improvement, and enhanced energy security.

The economic benefits are profound; efficiency investments made since 1980 have already reduced annual U.S. energy expenditures by nearly $800 billion, and the efficiency sector supports 2.2 million jobs.¹⁵

For households and businesses, efficiency directly translates to lower utility bills.¹⁸

From a public health perspective, reducing vehicle emissions and encouraging active transport leads to cleaner air, which in turn reduces the incidence of respiratory and cardiovascular diseases.¹⁹

Furthermore, active transport like walking and cycling provides direct physical health benefits, lowering societal healthcare costs.²²

For many policymakers and citizens, these immediate, tangible benefits related to jobs, cost savings, and health are the primary motivators for action.

The profound climate benefits, in this context, become a powerful, built-in bonus, making the case for investment compelling across a much broader political and social spectrum.

Measure 1.3: Scaling Carbon Removal and Land Use Management

The final component of overhauling our energy metabolism involves addressing the atmospheric legacy of past emissions.

This requires actively removing CO2​ from the atmosphere, enhancing the “respiratory” function of the planet.

This can be achieved through both nature-based and technological approaches.

In the United States, managed forests and other lands already act as a net sink, absorbing more CO2​ than they emit and offsetting about 13% of the nation’s gross GHG emissions.¹²

Nature-based solutions leverage and enhance natural carbon cycles.

Key strategies include reforestation (restoring forests on cleared land), afforestation (planting new forests), and improved soil carbon sequestration through agricultural practices like planting cover crops and agroforestry (integrating trees into croplands).⁸

These approaches offer significant co-benefits for biodiversity and ecosystem health.

Technological solutions, collectively known as carbon dioxide removal (CDR), are also emerging.

The most prominent is Direct Air Capture (DAC), a process that uses chemical and physical processes to scrub CO2​ directly from the ambient air, after which it can be concentrated and sequestered in deep geological formations.²⁴

Other methods include bioenergy with carbon capture and storage (BECCS), which involves burning biomass for energy and capturing the resulting

CO2​, and creating biochar, a stable form of charcoal that stores carbon in soil.²⁴

A sophisticated strategy recognizes that nature-based and technological removal methods are not interchangeable but are complementary tools that serve different purposes across different timescales and risk profiles.

Reforestation, for example, is a powerful, large-scale, and relatively low-cost method for long-term carbon storage, but it is not permanent; a forest can be destroyed by fire or disease, releasing its stored carbon back into the atmosphere.²⁴

DAC, in contrast, offers permanent, verifiable, and geographically flexible removal, but it is currently energy-intensive and expensive.²⁴

Viewing these through a metabolic lens, reforestation is akin to adopting a long-term “healthy diet” for the planet, gradually restoring the natural systems that regulate atmospheric carbon over decades.

DAC is more like “emergency surgery”—a precise, targeted intervention to rapidly remove a specific quantity of legacy pollution.

A comprehensive and resilient carbon removal strategy must therefore be a portfolio approach, investing in both the restoration of natural sinks for systemic, long-term health and the development of technological options for rapid, targeted, and permanent response.

---

Table 2: Summary of Mitigation Measures for Carbon Dioxide (CO2​)

Mitigation Measure	Primary Target Sector(s)	Key Economic & Health Co-Benefits
Decarbonizing Power and Heat Generation	Electricity & Heat Production	Creation of clean energy jobs, improved air quality, stable long-term energy prices, enhanced energy security.
Enhancing End-Use Efficiency & Electrification	Transportation, Buildings, Industry	Lower utility bills for consumers and businesses, job creation in retrofitting and manufacturing, improved public health from reduced air pollution and active transport.
Scaling Carbon Removal & Land Use Management	Land Use & Forestry, Industry	Enhanced biodiversity, improved soil health and agricultural productivity, creation of jobs in forestry and new carbon-tech industries.

---

Part II. Tackling Methane (CH4​): Closing the Loop on Our Waste Metabolism

Methane (CH4​) is the defining gas of metabolic inefficiency.

With a GWP 27 to 30 times that of CO2​ over a 100-year period, its impact on near-term warming is immense; it is responsible for approximately 30% of the rise in global temperatures since the Industrial Revolution.⁶

Methane emissions represent two primary forms of waste: fugitive, uncaptured energy leaking from fossil fuel infrastructure, and the gaseous byproduct of undigested organic matter from agriculture and landfills.⁵

Addressing methane, therefore, is not about inventing new chemistry but about achieving systemic efficiency—capturing lost value and closing the loops in our global waste metabolism.

According to the IPCC, global methane emissions must be reduced by about a third by 2030 to stay on a 1.5°C pathway.⁴

Measure 2.1: Transforming Agricultural Practices

Agriculture is the single largest source of anthropogenic methane emissions, stemming primarily from two areas: enteric fermentation (the digestive process of ruminant livestock like cattle) and manure management.⁸

A third major source is the cultivation of rice in flooded paddies.²⁷

Fortunately, a suite of effective mitigation strategies exists for each.

1. Reducing Enteric Fermentation: The most direct approach is to alter the animal’s diet. This includes improving the digestibility of feed, which allows the animal to absorb more nutrients and produce less methane.²⁶ More advanced solutions involve specialized feed additives that inhibit the microbes in the cow’s gut that produce methane. The synthetic molecule 3-nitroxypropanol (3-NOP), now approved for use in over 60 countries, can reduce methane emissions by around 30%.²⁶ Another promising additive is the red seaweed
   Asparagopsis, which has shown even higher mitigation potential in trials.²⁶
2. Improving Manure Management: Methane is produced when manure is stored in liquid form, such as in lagoons or slurry tanks. The most effective mitigation strategy is to capture this gas using anaerobic digesters—sealed vessels that process the manure, capture the resulting biogas (a mixture of methane and CO2​), and leave behind a nutrient-rich digestate that can be used as fertilizer.²⁸ The captured biogas can be burned to generate on-farm electricity and heat or, with further processing, upgraded to renewable natural gas (RNG) and injected into the commercial gas pipeline.²⁸
3. Optimizing Rice Cultivation: The traditional practice of continuously flooding rice paddies creates anaerobic conditions ideal for methane-producing microbes. A simple and effective alternative is Alternate Wetting and Drying (AWD), where fields are periodically drained and re-flooded. This practice can halve methane emissions while also reducing water use by up to a third, a crucial co-benefit in water-stressed regions.²⁷

The implementation of these measures, particularly anaerobic digestion, can do more than just cut emissions; it can serve as a catalyst for a rural circular bio-economy.

This approach transforms a linear waste stream (manure), which is often a source of water and air pollution and a financial liability for farmers, into a circular value chain.

The anaerobic digester becomes the hub of this new system, converting manure into two valuable assets: biogas, which provides a new revenue stream and enhances on-farm energy independence, and digestate, a high-quality organic fertilizer that reduces the need for costly synthetic inputs.²⁸

This reframes the entire economic model of farming.

The farmer is no longer just a producer of food but an integrated manager of bio-resources, creating a powerful, self-sustaining economic incentive for adoption that is far more compelling than a simple climate mandate.

A prime example is the extensive “manure-to-energy” program undertaken by Smithfield Foods, which aims to install covered anaerobic digesters across 90% of its hog finishing facilities in key states, capturing biogas and converting it into RNG to power thousands of homes.³⁰

This is not an environmental cost; it is a new business opportunity that aligns profitability with sustainability.

Measure 2.2: Abating Emissions from the Fossil Fuel Sector

The energy sector is the second-largest source of anthropogenic methane, responsible for nearly 130 million tonnes of emissions in 2023.³²

These emissions are primarily fugitive leaks from the production, processing, and transportation of oil and natural gas.

The International Energy Agency (IEA) has made it clear that a 75% reduction in these emissions is achievable by 2030 using existing, cost-effective technologies.³³

The core strategies are well-established:

1. Leak Detection and Repair (LDAR): This involves systematic programs to survey oil and gas infrastructure with tools like infrared cameras or aerial sensors to identify and repair leaks from valves, connectors, and other components.³⁵
2. Eliminating Non-Emergency Venting and Flaring: This means capturing the gas that is often intentionally released (vented) or burned off (flared) during routine operations and maintenance. A significant source of undercounted emissions comes from inefficient flaring; the IEA estimates the global average combustion efficiency of flares is only 92%, far below the commonly assumed 98%, meaning much more methane is being released unburned than previously thought.³²
3. Replacing High-Emitting Equipment: Certain components, like high-bleed pneumatic controllers that use gas pressure to operate valves, are designed to continuously vent methane. These can be replaced with low- or zero-emission alternatives, such as instrument air systems or electric actuators.³³

The economic case for these actions is exceptionally strong.

The IEA estimates that in 2023, approximately 40% of methane emissions from fossil fuel operations could have been avoided at no net cost, as the market value of the captured gas would have been sufficient to cover the abatement costs.³³

An annual global investment of just USD $15 billion would be required to deploy all available abatement measures in the oil and gas sector.²⁵

The fact that these low-cost, high-impact opportunities remain largely untapped points not to a technological or financial barrier, but to a clear failure of market incentives and regulatory oversight.

While voluntary industry initiatives exist, they have “not delivered demonstrable reductions on a wide scale”.³⁵

For an individual operator, the cost and effort of fixing thousands of small leaks can seem to outweigh the value of the gas saved at each point, even if the aggregate value is enormous.

This is a classic tragedy of the commons, where individual rational decisions lead to a collective negative outcome.

This situation can only be resolved through strong, binding government regulation.

Policies like the U.S. Inflation Reduction Act’s “Waste Emissions Charge” work by internalizing the external cost of methane pollution, creating a direct financial penalty for inaction and altering the economic calculus for operators.³⁷

Measure 2.3: Capturing Emissions from Municipal Solid Waste

The third major source of methane is the anaerobic decomposition of organic waste—such as food scraps, paper, and yard trimmings—in municipal solid waste landfills.⁵

As with agricultural manure, the mitigation strategy is twofold: capture the emissions from existing sources and prevent the problem from growing.

1. Landfill Gas Capture (LFG): At existing landfills, this involves installing a system of vertical wells and horizontal pipes to collect the methane-rich biogas generated within the waste mass. This captured gas must be treated and can then be flared to convert the methane to less-potent CO2​. A far better use, however, is to pipe it to an on-site generator to produce electricity or process it into RNG for pipeline injection.²⁹
2. Organic Waste Diversion: The most effective long-term strategy is to prevent organic materials from entering landfills in the first place. This requires implementing source-separation programs where households and businesses separate their organic waste, which is then collected and treated through composting or anaerobic digestion.²⁷

Viewing waste management through the metabolic framework reveals its potential as a critical link for creating powerful synergies between the urban, agricultural, and energy sectors.

The conventional approach treats agricultural waste, food waste, and energy production as separate problems to be solved in isolation.

A systemic approach, however, sees them as interconnected streams in a larger metabolism.

By co-digesting municipal organic waste (from Measure 2.3) with agricultural manure (from Measure 2.1) in regional anaerobic digesters, a community can achieve multiple benefits simultaneously.

This combined feedstock significantly boosts the production of renewable natural gas, contributing to energy decarbonization (Measure 1.1).

It dramatically reduces methane emissions from both landfills and manure lagoons.

And it produces a larger volume of high-quality organic fertilizer, which can be returned to farms to improve soil health and reduce the need for synthetic nitrogen fertilizers—a key strategy for mitigating nitrous oxide, as will be discussed in the next section.

This integrated approach transforms three separate environmental “problems” into a single, value-generating, circular solution.

---

Table 3: Summary of Mitigation Measures for Methane (CH4​)

Mitigation Measure	Primary Target Sector(s)	Key Economic & Health Co-Benefits
Transforming Agricultural Practices	Agriculture	New revenue streams for farmers (RNG, fertilizer), improved soil health, reduced water use (in rice), enhanced rural energy independence.
Abating Fossil Fuel Emissions	Energy (Oil, Gas, Coal)	Increased revenue from captured gas (often a net profit), improved worker safety, reduced local air pollution.
Capturing Waste Emissions	Waste Management	Generation of renewable energy (electricity, RNG), creation of valuable compost/fertilizer, job creation in green waste management.

---

Part III. Reducing Nitrous Oxide (N2​O): Rebalancing Our Nutrient Metabolism

Nitrous oxide (N2​O) is an often-overlooked but extremely potent greenhouse gas.

With a GWP of 273 and an atmospheric lifetime of over a century, its long-term warming impact is significant.⁶

It is also a major contributor to the depletion of the stratospheric ozone layer.³⁸

N2​O is the primary emission from an imbalanced “nutrient metabolism,” a system overloaded with reactive nitrogen.

The vast majority of these emissions—over 50% in California, for example—originate from agricultural soils, where microbes convert excess nitrogen from synthetic and organic fertilizers into N2​O.⁸

Smaller but still significant sources include industrial processes like the production of nitric and adipic acid, and fossil fuel combustion.⁴⁰

Measure 3.1: Implementing Precision Agriculture and Nutrient Stewardship

The most impactful strategy for reducing agricultural N2​O is to minimize the amount of excess nitrogen in the soil that is available for microbial conversion.

This is achieved by precisely matching nitrogen inputs to the dynamic needs of the crop throughout its growing season.

The guiding principle is the 4R Nutrient Stewardship Framework: applying the Right fertilizer source, at the Right rate, at the Right time, and in the Right place.⁴²

This framework is put into practice through a suite of precision agriculture technologies:

1. Variable Rate Technology (VRT): Instead of applying a uniform rate of fertilizer across an entire field, VRT uses GPS-guided farm equipment and detailed soil maps to apply customized rates to different zones within the field, delivering more nutrients where they are needed and less where they are not.⁴³
2. Enhanced Efficiency Fertilizers (EEFs): These are advanced formulations that control the release of nitrogen. This includes slow- or controlled-release fertilizers that meter out nutrients over time, and products containing nitrification inhibitors, which are compounds that temporarily suppress the microbial activity that produces N2​O.⁴²
3. Advanced Soil and Crop Monitoring: This involves moving beyond pre-season planning to active, in-season management. Farmers can use real-time soil nitrate tests or remote sensing data from drones or satellites to assess crop health and nitrogen needs on the fly, allowing them to adjust “side-dress” applications of fertilizer mid-season to meet peak crop demand precisely.⁴⁵

These practices have been shown to reduce N2​O emissions in corn systems by a remarkable 40-50%.⁴²

The most powerful lever for driving their adoption is that the primary motivation for farmers is not climate mitigation, but economic self-interest.

Nitrogen fertilizer is a major and costly input.

The technologies of precision agriculture are designed to optimize the use of this input, reducing waste and maximizing the return on investment.

A comprehensive study found that precision agriculture increases overall farm productivity by an estimated 4%, improves fertilizer placement efficiency by 7%, and reduces fossil fuel use by 6%.⁴⁷

The fact that practices that reduce

N2​O emissions also increase fertilizer efficiency creates a powerful alignment between environmental goals and farm profitability.⁴⁵

This means that policy and outreach efforts can achieve the greatest impact not by mandating emissions reductions, but by lowering the barriers to the adoption of these profitable technologies, for example, by providing financial incentives for equipment purchases or investing in rural broadband infrastructure to support data-intensive farming.⁴⁷

The climate benefits will naturally follow the path of economic optimization.

Measure 3.2: Deploying Abatement Technologies in Industrial Chemical Production

While agricultural emissions are diffuse and challenging to manage, a significant portion of industrial N2​O emissions comes from a few, highly concentrated point sources.

Specifically, N2​O is generated as a byproduct in the manufacturing of nitric acid (a key ingredient for synthetic fertilizer) and adipic acid (a precursor for nylon and other polymers).⁴⁰

Because these emissions are contained within the manufacturing facility and released through specific process vents, they are highly amenable to end-of-pipe abatement technologies.

These are typically secondary control systems installed in the exhaust stream that are designed to destroy the N2​O before it reaches the atmosphere.

Common methods include thermal decomposition (using high heat to break the N2​O molecule apart) or catalytic reduction, which uses a catalyst to convert N2​O into harmless nitrogen (N2​) and oxygen (O2​).

These technologies are mature, well-understood, and highly effective, with demonstrated destruction efficiencies of 80-90% or even higher.⁴⁰

This situation represents a “silver bullet” mitigation opportunity.

Unlike the millions of individual farms contributing to agricultural emissions, industrial N2​O comes from a relatively small number of large facilities.

The emissions are quantifiable, the technology is proven, and the impact is immediate and significant.

This stark contrast suggests a clear strategic priority for policymakers: aggressively and immediately mandate the installation of Best Available Abatement Technology at all nitric and adipic acid production facilities.

It is one of the most direct, measurable, and technologically certain climate mitigation actions available.

Measure 3.3: Optimizing Fuel Combustion and Pollution Controls

Nitrous oxide is also a minor byproduct of fossil fuel combustion, particularly in the engines of motor vehicles.

While a smaller source overall, it has been the site of one of the most successful, albeit unintentional, mitigation stories.

Between 1990 and 2022, N2​O emissions from mobile combustion in the United States plummeted by 56%.⁴⁰

This dramatic reduction was not the result of climate policy.

It was a direct consequence of air quality regulations, like the Clean Air Act, which were designed to combat urban smog and acid rain by targeting criteria air pollutants such as nitrogen oxides (NOx​), carbon monoxide (CO), and unburned hydrocarbons.

To meet these stringent standards, the automotive industry developed and deployed the three-way catalytic converter, a device in the exhaust system that uses catalysts like platinum and rhodium to convert these harmful pollutants into less harmful substances.⁴⁰

This historical success is a powerful example of a “co-benefit cascade.” The primary goal of the regulation was to improve local and regional air quality and public health.

The technology developed to achieve that goal—the catalytic converter—had the unintended but highly beneficial side effect of also being extremely effective at breaking down N2​O into harmless nitrogen gas.

This provides a crucial lesson for future policymaking: environmental regulations should not be developed in silos.

All major policies, whether they target water quality, waste management, or air pollution, should be systematically assessed for their potential climate co-benefits.

An integrated approach that recognizes these interconnections can unlock substantial, low-cost GHG reductions that might otherwise be overlooked, achieving multiple societal goals with a single, well-designed intervention.

---

Table 4: Summary of Mitigation Measures for Nitrous Oxide (N2​O)

Mitigation Measure	Primary Target Sector(s)	Key Economic & Health Co-Benefits
Precision Agriculture & Nutrient Stewardship	Agriculture	Increased farm profitability through reduced fertilizer costs, improved crop yields, enhanced water quality from less nutrient runoff.
Industrial Chemical Abatement	Industry (Chemical Production)	High-efficiency, low-cost abatement at point sources; potential for improved process control and operational efficiency.
Optimizing Fuel Combustion	Transportation, Energy	Drastically improved local and regional air quality, leading to significant public health benefits (reduced respiratory illness).

---

Part IV. Phasing Down Fluorinated Gases: Managing Our Synthetic Metabolism

Fluorinated gases—a family that includes hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6​), and nitrogen trifluoride (NF3​)—are the “synthetic toxins” of our industrial metabolism.

They do not occur in nature and are produced for specific industrial applications.⁴⁹

While emitted in smaller quantities than other GHGs, their impact is immense.

They are super-potent, with GWPs thousands of times that of

CO2​, and some, like PFCs and SF6​, have atmospheric lifetimes that stretch for thousands or even tens of thousands of years, making their warming effect effectively permanent on human timescales.⁶

They are used primarily as refrigerants in air conditioning and refrigeration systems, as aerosol propellants, and in specialized manufacturing processes like semiconductor fabrication.⁵⁰

Measure 4.1: Substitution with Low-GWP Alternatives

The cornerstone strategy for mitigating F-gas emissions is to replace them with climate-friendly alternatives.

This effort is part of a multi-generational technological transition.

First, the 1987 Montreal Protocol successfully orchestrated the phase-out of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) because they were depleting the stratospheric ozone layer.⁵²

HFCs, which are ozone-safe, were widely adopted as the primary replacement.⁵⁰

However, the potent greenhouse effect of HFCs created a new climate problem.

The global response was the 2016 Kigali Amendment to the Montreal Protocol, a landmark international treaty that commits signatory nations to an ambitious, legally binding phase-down of the production and consumption of HFCs by more than 80% over the next 30 years.⁵²

This single agreement is projected to avoid up to 0.5°C of global warming by 2100.⁵⁴

The transition is moving toward two main classes of low-GWP alternatives:

1. Natural Refrigerants: These are naturally occurring substances with very low or zero GWPs. They include ammonia (R-717, GWP=0), carbon dioxide (CO2​, R-744, GWP=1), and hydrocarbons such as propane (R-290, GWP=3).⁵⁶
2. Hydrofluoroolefins (HFOs): These are a newer generation of synthetic fluorinated refrigerants specifically engineered to have very short atmospheric lifetimes. This property means they break down quickly and thus have very low GWPs, often in the single digits.⁵⁰

The history of the Montreal Protocol and its Kigali Amendment provides the world’s most successful blueprint for tackling a global atmospheric crisis.

It demonstrates a proven formula: an international agreement sets clear, long-term, and legally binding phase-down targets.

This regulatory certainty gives industry the confidence to invest billions in research and development to create and commercialize alternatives, such as the HFOs developed by chemical manufacturers.⁵⁹

The treaty includes trade provisions that restrict member countries from trading in controlled substances with non-parties, preventing the problem from simply shifting to unregulated markets.⁵⁹

Finally, a multilateral fund provides financial and technical assistance to developing countries to help them meet their compliance obligations.⁵⁹

This integrated model of science-based targets, regulatory certainty, industry innovation, and international cooperation is a powerful template for addressing other classes of industrial pollutants.

Measure 4.2: Enforcing Strict Lifecycle Refrigerant Management

Unlike CO2​ from a smokestack, F-gas emissions are almost entirely “fugitive.” They are not intentionally released but escape from equipment due to leaks during operation, improper servicing procedures, and failure to recover the gas at the end of the equipment’s life.⁵⁰

Therefore, a critical mitigation strategy is robust lifecycle refrigerant management, often referred to as stewardship.

This involves a chain of custody and best practices from production to disposal:

1. Leak Prevention and Repair: This includes designing more robust, leak-tight systems and implementing regulations that mandate regular leak inspections and prompt repairs for commercial refrigeration and air conditioning equipment.⁵⁰
2. Professional Handling and Servicing: In the U.S. and other jurisdictions, it is illegal to knowingly vent refrigerants into the atmosphere. Regulations require that any maintenance, service, repair, or disposal of refrigeration and air-conditioning equipment be performed only by certified technicians who are trained in proper handling and recovery procedures.⁶¹
3. End-of-Life Recovery and Reclamation: When equipment is decommissioned, regulations mandate that the refrigerant charge be recovered using certified equipment. This recovered gas can then be recycled for reuse or sent to a reclamation facility, where it is purified back to virgin quality standards. Gas that cannot be reclaimed must be destroyed by certified high-temperature incineration processes.⁵⁶

This focus on stewardship reveals that effective F-gas mitigation is less a challenge of scientific discovery and more a challenge of logistics, maintenance, and workforce development.

The critical infrastructure required is not a new type of power plant but a robust, nationwide network of certified technicians, refrigerant recovery systems, and certified reclamation facilities.

The key actors are HVAC professionals, automotive mechanics, and appliance recyclers.

This implies that effective policy must focus on building this “soft infrastructure.” Key interventions include establishing and enforcing rigorous technician certification programs, creating a clear reverse logistics chain for recovered gases, and providing financial support for the expansion of reclamation capacity, such as through the grants provided by the EPA’s American Innovation and Manufacturing (AIM) Act.⁶²

This is a fundamentally blue-collar, skills-based climate solution that requires sustained investment in vocational training, certification, and supply chain management.

Measure 4.3: Process Optimization and Abatement in High-Tech Manufacturing

Certain high-tech industries, most notably semiconductor manufacturing, use a range of potent F-gases (PFCs, HFCs, SF6​, NF3​) and N2​O for highly specialized processes like plasma etching of silicon wafers and cleaning the inside of manufacturing chambers.⁶³

Emissions occur because these processes are not 100% efficient; anywhere from 10% to 80% of the input gas can pass through the tool unreacted and be released in the exhaust stream.⁶³

Mitigation in this sector follows a clear and logical hierarchy, mirroring best practices for industrial decarbonization more broadly:

1. Process Optimization: The first step is to improve material efficiency by fine-tuning the manufacturing process itself—adjusting gas flows, pressures, and power levels—to use less of the potent GHG per wafer produced.⁶³
2. Gas Substitution: Where possible, manufacturers work to replace higher-GWP gases with alternatives that are either less potent or are utilized more efficiently in the chemical reaction, resulting in lower emissions.⁶³
3. Point-of-Use Abatement: For the remaining, unavoidable emissions, the final step is to install dedicated abatement systems on the exhaust lines of the manufacturing tools. These systems, often using thermal or catalytic oxidation, are designed to capture and destroy the unreacted GHGs before they are vented to the atmosphere.⁶⁴

This three-step strategy for the semiconductor industry serves as a perfect microcosm of the broader framework for all industrial decarbonization as outlined by the IPCC.¹³

The IPCC’s overarching strategy for industry follows the same hierarchy: first, reduce demand for primary materials through material efficiency and circular economy solutions; second, switch to low-carbon energy and feedstocks like electricity and hydrogen; and third, use carbon capture and storage for any remaining, unavoidable process emissions.

The fact that this exact logic is successfully applied in one of the world’s most technologically complex and sensitive manufacturing environments validates the IPCC’s framework.

It demonstrates that these high-level principles are not merely theoretical but form a practical, effective, and proven pathway for decarbonizing even the most challenging industrial sectors.

---

Table 5: Summary of Mitigation Measures for Fluorinated Gases (F-Gases)

Mitigation Measure	Primary Target Sector(s)	Key Economic & Health Co-Benefits
Substitution with Low-GWP Alternatives	Refrigeration & Air Conditioning, Aerosols, Foams	Drives innovation in the chemical and manufacturing sectors, creates markets for new products, protects the stratospheric ozone layer.
Lifecycle Refrigerant Management	Service & Maintenance Sector, Waste Management	Creates skilled jobs for certified technicians, reduces the need for virgin refrigerant production through reclamation, prevents release of harmful chemicals.
Industrial Process Optimization & Abatement	Industry (Semiconductor, Electronics)	Improves manufacturing efficiency and reduces material costs, enhances corporate reputation for environmental stewardship.

---

V. Synthesis and Forward Outlook: Co-Benefits, Policy Integration, and the Path to Net-Zero

Viewing greenhouse gas emissions through the lens of our global “metabolism” fundamentally changes the strategic approach to mitigation.

It shifts the focus from a disconnected series of end-of-pipe treatments to a holistic redesign of the underlying systems of production and consumption.

This framework reveals the deep interconnections between seemingly disparate problems and, in doing so, illuminates more powerful, integrated solutions.

An anaerobic digester that co-digests farm manure and city food waste is no longer just a methane-reduction device; it is a nexus point in a circular economy that simultaneously reduces CH4​, displaces fossil fuels (reducing CO2​), and produces organic fertilizer that can reduce the need for synthetic nitrogen (reducing N2​O).

This is the power of systemic thinking.

This analysis has also revealed that the most compelling case for climate action is often built on a foundation of immediate, tangible co-benefits.

The transition to a net-zero economy is not a story of sacrifice, but an opportunity to build a more prosperous, healthy, and resilient society.

• Economic Benefits: The shift to clean energy and greater efficiency is a massive engine for job creation and economic stimulus. It lowers energy costs for households and makes businesses more competitive. It creates new revenue streams for farmers and turns waste liabilities into valuable assets.¹⁶
• Public Health Benefits: Decarbonizing our energy and transportation systems drastically reduces the air pollution that causes millions of premature deaths and chronic respiratory illnesses worldwide. Promoting active transportation and creating urban green spaces improves both physical and mental well-being, reducing the burden on healthcare systems.²⁰
• Environmental Benefits: Beyond climate mitigation, these actions yield a cascade of positive environmental outcomes, including improved water quality from reduced fertilizer runoff, enhanced biodiversity through better land management, and the continued protection of the stratospheric ozone layer.³⁸

Finally, this report underscores the indispensable role of smart, well-designed public policy.

Technology provides the tools for transformation, but policy provides the direction and momentum.

The global success of the Montreal Protocol in phasing out ozone-depleting substances and now HFCs provides a clear blueprint for how international cooperation and regulatory certainty can drive industry innovation at a global scale.⁵²

The targeted interventions of legislation like the U.S. Inflation Reduction Act, which uses both incentives and penalties to accelerate change, show the power of national policy to overcome market failures.³⁷

The clear need for binding regulations to curb methane leaks from the fossil fuel industry demonstrates that voluntary action alone is insufficient to address entrenched problems.³⁵

My own journey began in the frustration of a siloed, reactive approach to sustainability.

The realization that we were treating the symptoms of a dysfunctional metabolism, rather than the disease itself, was the critical turning point.

The path forward is not to build a better filter for every smokestack, but to redesign the engine.

By focusing on the systemic health of our energy, waste, and nutrient metabolisms, we can move beyond a strategy of incremental fixes.

We can unlock a cascade of economic, social, and environmental benefits and, in doing so, build a more prosperous, equitable, and enduring future for all.

Works cited

1. IPCC report: immediate action can secure a liveable future | Copernicus, accessed August 13, 2025, https://atmosphere.copernicus.eu/ipcc-report-immediate-action-can-secure-liveable-future
2. Top Takeaways from the IPCC’s AR6 Synthesis Report: Climate Change 2023 – ALL4 Inc, accessed August 13, 2025, https://www.all4inc.com/4-the-record-articles/top-takeaways-from-the-ipccs-ar6-synthesis-report-climate-change-2023/
3. Summary for Policymakers – IPCC, accessed August 13, 2025, https://www.ipcc.ch/report/ar6/syr/summary-for-policymakers/
4. The evidence is clear: the time for action is now. We can halve emissions by 2030. – IPCC, accessed August 13, 2025, https://www.ipcc.ch/2022/04/04/ipcc-ar6-wgiii-pressrelease/
5. Overview of Greenhouse Gases | US EPA, accessed August 13, 2025, https://www.epa.gov/ghgemissions/overview-greenhouse-gases
6. Climate Change Indicators: Greenhouse Gases | US EPA, accessed August 13, 2025, https://www.epa.gov/climate-indicators/greenhouse-gases
7. The Principal Greenhouse Gases and Their Sources | The National Environmental Education Foundation (NEEF), accessed August 13, 2025, https://www.neefusa.org/story/climate-change/principal-greenhouse-gases-and-their-sources
8. Global Greenhouse Gas Overview | US EPA, accessed August 13, 2025, https://www.epa.gov/ghgemissions/global-greenhouse-gas-overview
9. Actions for a healthy planet | United Nations, accessed August 13, 2025, https://www.un.org/en/actnow/ten-actions
10. How You Can Help Reduce Greenhouse Gas Emissions at Home …, accessed August 13, 2025, https://www.nps.gov/pore/learn/nature/climatechange_action_home.htm
11. How you can reduce your carbon footprint – WWF, accessed August 13, 2025, https://explore.panda.org/climate/how-to-reduce-your-carbon-footprint
12. Sources of Greenhouse Gas Emissions | US EPA, accessed August 13, 2025, https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
13. Chapter 11: Industry – IPCC, accessed August 13, 2025, https://www.ipcc.ch/report/ar6/wg3/chapter/chapter-11/
14. Reduce Your Carbon Footprint at Home – Mass.gov, accessed August 13, 2025, https://www.mass.gov/info-details/reduce-your-carbon-footprint-at-home
15. Energy efficiency and economic stimulus – Analysis – IEA, accessed August 13, 2025, https://www.iea.org/articles/energy-efficiency-and-economic-stimulus
16. Energy Efficiency Impact Report – Why Energy Efficiency Matters, accessed August 13, 2025, https://energyefficiencyimpact.org/
17. New Report Showcases the Far-Reaching Benefits of Energy Efficiency | ACEEE, accessed August 13, 2025, https://www.aceee.org/press-release/2022/12/new-report-showcases-far-reaching-benefits-energy-efficiency
18. Transportation & Fuels Pillar | Department of Energy, accessed August 13, 2025, https://www.energy.gov/eere/transportation-fuels-pillar
19. 6 Benefits of Sustainable Transportation – AirCare, accessed August 13, 2025, https://getaircare.com/blog/6-benefits-of-sustainable-transportation/
20. Energy, Transportation, Air Quality, Climate Change, Health Nexus: Sustainable Energy is Good for Our Health – PMC – PubMed Central, accessed August 13, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC5963114/
21. 5 Environmental Benefits of Sustainable Transportation, accessed August 13, 2025, https://transportation.ucla.edu/blog/5-environmental-benefits-sustainable-transportation
22. Active Transportation | US Department of Transportation, accessed August 13, 2025, https://www.transportation.gov/mission/office-secretary/office-policy/active-transportation/active-transportation
23. Active Transportation in Urban Areas: Exploring Health Benefits and Risks, accessed August 13, 2025, https://ncceh.ca/sites/default/files/Active_Transportation_in_Urban_Areas_June_2010_0.pdf
24. 6 Ways to Remove Carbon Pollution from the Atmosphere | World Resources Institute, accessed August 13, 2025, https://www.wri.org/insights/6-ways-remove-carbon-pollution-sky
25. Methane Abatement – Energy System – IEA, accessed August 13, 2025, https://www.iea.org/energy-system/fossil-fuels/methane-abatement
26. From Better Breeding to Cow-Burp Vaccines, Emerging Solutions Could Curb Agricultural Emissions – World Resources Institute, accessed August 13, 2025, https://www.wri.org/insights/reducing-agricultural-methane-new-solutions
27. Methane | Climate & Clean Air Coalition, accessed August 13, 2025, https://www.ccacoalition.org/short-lived-climate-pollutants/methane
28. Methane Management in Agriculture – About Chubb, accessed August 13, 2025, https://about.chubb.com/content/dam/chubb-sites/chubb/about-chubb/citizenship/climate/ag-hub/pdfs/ag-methane-management.pdf
29. Benefits and costs of mitigating methane emissions | Climate & Clean Air Coalition, accessed August 13, 2025, https://www.ccacoalition.org/content/benefits-and-costs-mitigating-methane-emissions
30. Future of Hog Waste to RNG, accessed August 13, 2025, https://www.epa.gov/sites/default/files/2019-03/documents/future-of-hog-waste-to-rng.pdf
31. Smithfield Foods to expand manure-to-energy projects | Biomass Magazine, accessed August 13, 2025, https://biomassmagazine.com/articles/smithfield-foods-to-expand-manure-to-energy-projects-15711
32. Understanding methane emissions – Global Methane Tracker 2024 …, accessed August 13, 2025, https://www.iea.org/reports/global-methane-tracker-2024/understanding-methane-emissions
33. Methane emissions in a 1.5 °C pathway – Global Methane Tracker 2024 – Analysis – IEA, accessed August 13, 2025, https://www.iea.org/reports/global-methane-tracker-2024/methane-emissions-in-a-15-0c-pathway
34. New IEA report highlights importance of cutting methane from fossil fuels in blueprint for global action, accessed August 13, 2025, https://www.catf.us/2021/10/methane-fossil-fuels-iea-report-75/
35. Strategies to reduce emissions from oil and gas operations – Global …, accessed August 13, 2025, https://www.iea.org/reports/global-methane-tracker-2023/strategies-to-reduce-emissions-from-oil-and-gas-operations
36. How can we reduce methane emissions? – World Bank, accessed August 13, 2025, https://www.worldbank.org/en/programs/gasflaringreduction/methane-explained
37. Methane Emissions Reduction Program | US EPA, accessed August 13, 2025, https://www.epa.gov/inflation-reduction-act/methane-emissions-reduction-program
38. Cutting farm nitrous oxide emissions helps climate and ozone layer – University of Sheffield, accessed August 13, 2025, https://sheffield.ac.uk/news/cutting-farm-nitrous-oxide-emissions-helps-climate-and-ozone-layer
39. Nitrous oxide emissions from agricultural soils challenge climate sustainability in the US Corn Belt | PNAS, accessed August 13, 2025, https://www.pnas.org/doi/10.1073/pnas.2112108118
40. Nitrous Oxide Emissions | US EPA, accessed August 13, 2025, https://www.epa.gov/ghgemissions/nitrous-oxide-emissions
41. TECHNICAL PROPOSAL Evaluating Mitigation Options of Nitrous Oxide Emissions in California Cropping Systems, accessed August 13, 2025, https://ww2.arb.ca.gov/sites/default/files/2020-05/proposal11-313.pdf
42. 10 Proven Ways to Reduce Nitrous Oxide Emissions in 2025 | Villa Treatment Center, accessed August 13, 2025, https://thevillatreatmentcenter.com/reduce-nitrous-oxide-emissions/
43. Benefits and Evolution of Precision Agriculture – USDA ARS, accessed August 13, 2025, https://www.ars.usda.gov/oc/utm/benefits-and-evolution-of-precision-agriculture/
44. Management Strategies to Mitigate N2O Emissions in Agriculture – PMC – PubMed Central, accessed August 13, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC8949344/
45. Reduce Nitrous Oxide Emissions | UC Agriculture and Natural Resources, accessed August 13, 2025, https://ucanr.edu/site/solution-center-nutrient-management/reduce-nitrous-oxide-emissions
46. We can feed a growing population while shrinking fertilizer pollution. Here’s how. | EDF, accessed August 13, 2025, https://blogs.edf.org/growingreturns/2024/12/18/reducing-nitrous-oxide/
47. Study Shows Precision Agriculture Improves Environmental …, accessed August 13, 2025, https://www.croplife.com/smart-tech/study-shows-precision-agriculture-improves-environmental-stewardship-while-increasing-yields/
48. Precision Agriculture: Benefits and Challenges for Technology Adoption and Use | U.S. GAO, accessed August 13, 2025, https://www.gao.gov/products/gao-24-105962
49. Greenhouse Gases | US EPA, accessed August 13, 2025, https://www.epa.gov/report-environment/greenhouse-gases
50. Fluorinated Gas Emissions | US EPA, accessed August 13, 2025, https://www.epa.gov/ghgemissions/fluorinated-gas-emissions
51. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2022 – Industrial Processes and Product Use, accessed August 13, 2025, https://www.epa.gov/system/files/documents/2024-04/us-ghg-inventory-2024-chapter-4-industrial-processes-and-product-use_04-18-2024.pdf
52. Kigali Amendment – Wikipedia, accessed August 13, 2025, https://en.wikipedia.org/wiki/Kigali_Amendment
53. Recent International Developments under the Montreal Protocol | US EPA, accessed August 13, 2025, https://www.epa.gov/ozone-layer-protection/recent-international-developments-under-montreal-protocol
54. About Montreal Protocol – UNEP, accessed August 13, 2025, https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol
55. www.unep.org, accessed August 13, 2025, https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol#:~:text=Under%20the%20Kigali%20Amendment%2C%20actions,a%20truly%20unparalleled%20contribution%20to
56. Alternative Refrigerants | Project Drawdown®, accessed August 13, 2025, https://drawdown.org/solutions/alternative-refrigerants
57. Climate-friendly alternatives to HFCs – European Commission, accessed August 13, 2025, https://climate.ec.europa.eu/eu-action/fluorinated-greenhouse-gases/climate-friendly-alternatives-hfcs_en
58. Acceptable Refrigerants and their Impacts | US EPA, accessed August 13, 2025, https://www.epa.gov/mvac/acceptable-refrigerants-and-their-impacts
59. The Kigali Amendment is a Win for Climate and U.S. Industry, accessed August 13, 2025, https://clcouncil.org/blog/the-kigali-amendment-is-a-win-for-climate-and-u-s-industry/
60. What can I do? – Fluorinated Greenhouse Gases – Climate Action, accessed August 13, 2025, https://climate.ec.europa.eu/eu-action/fluorinated-greenhouse-gases/what-can-i-do_en
61. U.S. SUBMISSION ISSUES RELATING TO HFCs, PFCs, AND SF6 – UNFCCC, accessed August 13, 2025, https://unfccc.int/sites/default/files/subusa.pdf
62. Protecting Our Climate by Reducing Use of HFCs | US EPA, accessed August 13, 2025, https://www.epa.gov/climate-hfcs-reduction
63. Semiconductor Industry | US EPA, accessed August 13, 2025, https://www.epa.gov/eps-partnership/semiconductor-industry
64. Advancements in greenhouse gas emission reduction methodology for fluorinated compounds and N2O in the semiconductor industry vi – Frontiers, accessed August 13, 2025, https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2023.1234486/pdf
65. Advancements in greenhouse gas emission reduction methodology for fluorinated compounds and N2O in the semiconductor industry via abatement systems – Frontiers, accessed August 13, 2025, https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2023.1234486/full
66. The Economic Value of Health Benefits Associated with Urban Park Investment – PMC, accessed August 13, 2025, https://pmc.ncbi.nlm.nih.gov/articles/PMC10049315/
67. Agriculture: sustainable crop and animal production to help mitigate nitrous oxide emissions – USDA ARS, accessed August 13, 2025, https://www.ars.usda.gov/ARSUserFiles/31831/2014%20snyder%20et%20al.pdf