Krista Kurth, Ph.D.
Fluorinated Gases, Nitrous Oxide, and Methane, Oh My!
Updated: Jul 15, 2021
Learn how you can help reduce their threat to global warming
In the classic Wizard of Oz story, Dorothy, the Tin Man, and the Scarecrow overcome unseen threats by repeatedly naming their not-yet-visible nemeses as they make their way down the yellow brick road to the Emerald City. “Lions, and Tigers, and Bears, Oh My!” Later, when they meet the Cowardly Lion, they are well prepared for the potential threat.
Those of us walking the path to a green future, like my neighbor who asked me if home composting produces methane like landfills do, can similarly get ready by naming the three greenhouse gases (GHG) that are not as much a part of the climate crisis conversation: fluorinated gases, nitrous oxide, and methane. These three gases, like carbon dioxide, are all top contributors to global warming.
Since I, and many others, have written extensively about carbon and how to draw it out of the atmosphere (see Let Us Help the Earth Help Us and How Does the World Get to Net-Zero by 2050?), I’m going to focus on the other three main GHGs here. I will address three questions:
What are they?
Where do they come from?
What can we do to decrease them and their impact?
What Are They?
Drawing on information from various sources (the EPA, NASA’s site on climate change for kids, Popular Science, The National Environmental Education Foundation, and this Guardian article) here are definitions of each gas:
Methane (CH4), an odorless, colorless, gas made of carbon and hydrogen that has both beneficial and harmful characteristics, is less abundant in the atmosphere than CO2 and has a shorter lifespan but is 20% more potent as a greenhouse gas contributing to global warming. It is currently used to produce chemicals like ethanol, methyl chloride, and ammonia, which are used as fertilizers and explosives. This gas is also a fuel source for ovens, turbines, automobiles, and rockets. Currently, concentrations of this gas are about 2.5 times the amount in preindustrial times. Methane also affects air quality because it contributes to the formation of ground level ozone, a dangerous air pollutant.
One thing to keep in mind as you read about these gases is there are two key characteristics that determine their impact on climate change: how long they remain in the atmosphere and their ability to absorb energy. Methane remains for much less time than CO2 but it absorbs much more energy while it is in the atmosphere.
Nitrous oxide (N2O), which we know as laughing gas, a naturally occurring part of the nitrogen cycle created by bacteria in soil and the ocean. It not only damages the ozone layer but is also an even more powerful contributor, per gram, to climate change than methane and CO2. The EPA website (linked at the beginning of the paragraph) states that “a pound of N2O gas has the equivalent warming effect of 300 times that of one pound of carbon dioxide.” This GHG also stays in the atmosphere for around 120 years, making its impact long lasting.
Fluorinated gases (HFCS, PFCS, SF6) is a group of gases not created in nature that also damage the ozone layer and contribute significantly to global warming. The group (also called F-gases), which includes hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, are all High Global Warming Potential gases (“High GWP gases”) even though they make up a smaller percentage of emissions. They are more potent per gram than nitrous oxide, remain in the atmosphere for a very long time (ranging from 270 to 50,000 years depending on the gas) and the sunlight can only remove them from the upper atmosphere.
Where Do They Come From?
Methane which is valued for energy production, comes from both natural causes and human activity. Wetlands release this gas as do oceans, sediments, volcanos, wildfires, and termites in smaller amounts. The tundra as it melts, because of global warming, may also release methane. However, the largest emissions come from man-made sources such as during the production and transport of coal, natural gas, and oil, as well as from agriculture (particularly rice fields and livestock) and the decaying of organic waste in city landfills. The EPA graph shows human activities account for over 60% of total methane emissions.
According to Resilience.org, fossil-fuels produce the most methane. Since methane is the primary element in natural gas, “when energy companies drill wells, ‘frac’ wells, and pump natural gas through vast distribution networks some of that methane escapes. Oil and coal production also release methane — often vented into the atmosphere from coal mines and oil wells.”
Next on the list are livestock, which emit methane from their stomachs via their mouths (enteric fermentation). Liquid manure stored on large, concentrated animal farms (CAFO’s) also emits methane. You can learn more about sources of methane at the methane tracker website.
Nitrous Oxide also comes from both natural and human sources. However, it is our human activities (overuse of fertilizer in agriculture, land use, wastewater management, manufacturing, transportation, and burning fossil fuels and solid waste) that is most increasing the concentration of this gas in the atmosphere. As the graph shows, agriculture is the largest source.
Fluorinated Gas emissions are all caused by human activity. Aluminum and semiconductor manufacturing lead to the mission of most fluorinated gases. According to the graph, HFCs from refrigerators and air conditioners being used as substitutes for ozone depleting gases are the largest source of fluorinated gas emissions and the fastest growing contributor to GHG emissions. Foams and aerosol cans also play a significant role.
How Do We Reduce Them and Their impact?
Methane: In May 2021 the UNEP released a statement about the latest global methane assessment, stating that we can cut methane emissions by 45% by 2030 in a cost effective way, using existing technology. Inger Andersen, Executive Director of UNEP said, “Cutting methane is the strongest lever we have to slow climate change over the next 25 years and complements necessary efforts to reduce carbon dioxide… We need international cooperation to urgently reduce methane emissions as much as possible this decade.”
Reducing methane is a “low-hanging fruit” on the climate solution tree. If we work now to minimize it, it will help moderate global warming and give us time to draw more carbon out of the atmosphere. While many of the methods for reducing methane require corporate and government action, there are things we can do as individuals to help reduce this potent greenhouse gas. I categorize these actions by the largest sources of emissions (Fossil Fuels, Agriculture, and Landfills/Waste sites).
Reduce methane emissions from fossil fuel production by:
Signing petitions, like the ActionNetwork's, Move On's, and Change.org's, demanding fossil fuel companies fix methane gas leaks, capture methane gas, stop venting unwanted gas, and shutting down pipelines.
Joining protests, like the DefundLine3 and Honor the Earth's efforts, to stop the funding for and construction of new gas pipelines. More and more pipelines are now being cancelled.
Buying renewable energy to support the shift away from fossil fuel production and use.
Asking your local government and large companies that you buy from to switch to renewable energy.
Asking your government representatives to enact policies focused on minimizing emissions from the fossil-fuel sector, like banning venting and minimizing leaks from drilling and fracking and from pipes.
Reduce methane emissions from agriculture by:
Reducing beef consumption from industrial farms by buying meat that is pasture raised from a farm using regenerative agriculture practices.
Eating a more plant rich diet.
Buying organic, locally sourced meat and dairy. Organic farmers keep livestock longer, which lowers the total number of cows emitting methane in the atmosphere.
Buying food from companies that source regenerative ingredients. Thrive Market, Danone, and Oatly are three companies committed to regenerative agriculture.
Supporting farms that use “digesters” to process cow manure into biogas.
Reduce methane emissions from landfills by:
Asking your municipality to commit to better sewage treatment and capture methane from landfills.
Wasting less food. This article has tips on best to do that.
Petitioning your local grocery stores and restaurants to donate food instead of putting the waste in landfills. See this petition to the US Congress, and this one to grocery stores from Care2.
Reducing the amount of food waste that you put in your trash and send to the landfill. Food cannot biodegrade properly in landfills. However, you can compost scraps, either in your backyard or by participating in a city run compost program. This article has tips on how to start a home compost easily. Unlike in landfills, when you compost at home, methods like open pile, static pile, in-vessel, windrow, and vermicomposting, include air in the composting process. Since methane-producing microbes are not active in the presence of oxygen, composting at home produces less methane. The more air included in the composting process, the more carbon dioxide that compost emits instead of methane.
Following the guidance of the EPA’s Food Recovery Hierarchy.
Nitrous Oxide: Like Methane, the three primary sources of nitrous oxide are fossil fuels, landfills, and agriculture. Since the actions listed above for methane also apply to nitrous oxide, I won’t repeat them here. However, there are a few additional actions you can take to reduce nitrous oxide in agriculture.
According to Ula Chrobak in this recent article, before the rise of modern agriculture, most agricultural nitrogen came from compost, manure and nitrogen-fixing microbes. That changed when scientists introduced industrial fertilizer in the early 1900s. Excess fertilizer also runs off the soil and into waterways, causing pollution, algae blooms and dead zones.
Reduce nitrous oxide emissions from agriculture by:
Buying organic and regeneratively farmed fruits and vegetables. These types of farms minimize the use of synthetic fertilizers that include nitrous oxide.
Buying from local farmers markets and asking the farmers if they use no-till practices and no/minimal fertilizers.
Asking your government representatives to pass policies that reduce nitrous oxide use in agriculture and its runoff.
Advocating for a new farm bill (2023 in the US) that addresses the reduction of methane and nitrous oxide emissions from agriculture. You can learn more about what making the 2023 farm bill better at Kiss the Ground. They will soon have information posted on their site.
Becoming a soil steward and advocate and growing your own regenerative food. Kiss the Ground has courses on regenerative gardening and Green America has information on how to start your own Victory Garden.
Fluorinated Gases: Since these gases are all fabricated, it is up to us to change how we manufacture and use items that contribute to these emissions.
Reduce fluorinated gas emissions by:
Buying pump spray products instead of aerosol cans.
Disposing of your old refrigerators and air conditioners properly. Replace them with new ones that use safer alternative gases.
Signing petitions asking large grocery store chains to repair and maintain their equipment so that gases don’t leak from the commercial fridges in their stores and to use alternatives. Check out Green America’s Cool It campaign.
Asking your government representatives to pass bills that limit over time the most important F-gases that are used; ban the use of F-gases in some equipment, such as household fridges, for which less harmful alternatives are widely available today; prevent emissions from existing equipment by requiring companies to service them properly and recover the gases at the end of the equipment’s life; and requiring the use of alternatives like ammonia and captured carbon dioxide. The EU is already taking action to reduce the use of F-gases by two-thirds by 2030. The US EPA also recently issued a new rule to reduce the production and use of HFCs. Developed countries, via the Kigali Amendment to the Montreal Protocol, agreed to reduce HFCs by 85% between 2019 and 2036.
It is clear from the recent heat waves rocking the globe that the consequences of climate change are already here. While it will take a while to remove carbon from the atmosphere, we can start addressing the crisis now by doing what we can to reduce the other three significant greenhouse gases. What will you do in your daily life to reduce fluorinated gases, nitrous oxide, and methane?
I wish you all the best in your efforts. Together we can make a difference.