Yale Experts Explain Methane Emissions

Graphic showing the outline of a cow
November 18, 2024

As a greenhouse gas, methane is 80 times more potent than CO2 in the first 20 years after it is released into the atmosphere. Last year, methane emissions rose faster than at any time in recorded history, imperiling efforts to limit global warming by mid-century.

Cutting methane emissions quickly offers the fastest route to slowing the rate of global climate change, which is why nations gathering this month for the COP29 climate summit in Azerbaijan are focused on measuring progress on the methane-reduction commitments they have made over the past three years.

Peter Raymond is the senior associate dean of research and doctoral studies at Yale School of the Environment and helped produce the Global Methane Budget 2024, which documented how methane emissions are accelerating at their fastest rate ever recorded.

Steven Hamburg ’77 M.F.S., ’84 Ph.D. is senior vice president and chief scientist at Environmental Defense Fund and executive manager of MethaneSAT, a satellite launched in March 2024 that makes high-precision measurements of methane and carbon dioxide emissions from human activity around the world.

In a Q&A, Raymond and Hamburg discuss how methane is accelerating global warming, how cutting emissions could help stabilize our climate, and whether you should ditch your gas-burning stove. This interview was edited and condensed for clarity.

Q: What are the biggest anthropogenic sources of methane emissions?

HAMBURG: The biggest anthropogenic source is agriculture, particularly enteric fermentation—cows belching. Other agricultural sources include rice cultivation and manure management, which generates methane when it becomes anaerobic. The second largest source is the energy system, mainly from oil and gas production but also coal production. The third major source is waste, particularly landfills where organic matter decomposes anaerobically, producing methane. Natural sources include wetlands and other ecosystems with anaerobic conditions. Additionally, there’s a positive feedback loop: as the climate warms, natural systems like tropical wetlands and Arctic permafrost regions may produce more methane, indirectly caused by human-induced climate change.

Q: Why is methane of particular concern for global warming?

HAMBURG: Methane is the second most important greenhouse gas in terms of its warming of the planet, responsible for about 30% of the warming we’re currently experiencing. So you can’t solve the climate problem without addressing methane. But the good news is that methane is a short-lived climate pollutant, which means if you reduce emissions, concentrations in the atmosphere will decline relatively quickly and with it the warming it has caused.

RAYMOND: Methane is a very strong greenhouse gas with high radiative forcing, meaning it efficiently traps long-wave radiation and reflects it back to Earth. However, its atmospheric residence time is short, averaging about 10 years, compared to CO2, which remains for centuries. Because methane is so effective at trapping heat, reducing its concentration can quickly lower its impact on global warming.

Q: Why does reducing methane emissions matter?

HAMBURG: If we reduce the amount of methane that we emit, we can slow the rate of warming quite dramatically. For example, we’re losing summer sea ice in the Arctic and that has a very damaging impact because sea ice reflects a lot of sunlight and, in turn, warming. You can greatly increase the probability that summer sea ice will persist over the long term if we reduce methane emisisons.  Now it’s critical to say it’s not methane or carbon dioxide, it’s methane and carbon dioxide. But if we want to slow the rate of change of our climate over the next few decades, methane mitigation is a far more potent tool.

Q: What are the most effective ways to reduce methane emissions? What holds the most potential?

RAYMOND: One of the biggest sources to target is leaks from natural gas infrastructure. Identifying and fixing leaks, especially during well development and along natural gas pipelines, is crucial.

HAMBURG: Most of the time, methane emissions from oil and gas leaks can be eliminated at no net cost to the companies. We are still working through numbers, but we should be able to reduce these emissions by a factor of 10 by addressing leaks, venting, and flaring. And when you reduce emissions, you actually produce more product, which you can put into the pipe and sell; if you’re not emitting it, you can actually sell it to someone.

Q: Once methane emitters are identified, do we have the right policies or penalties in place to do something about it?

RAYMOND: There are some policies in the U.S. aimed at tightening methane emissions, although some were rolled back during the Trump presidency. Policy levers exist, along with public opinion levers. Groups like Environmental Defense Fund can use the data they collect to influence both policy and public opinion.

Q: What is the agriculture industry doing to address the methane problem?

HAMBURG: There is work being done to manage the diet and health of cows by using additives in livestock feed. There’s a product called Bovair that has shown an ability to reduce methane emissions by 30%. Rice is another one—you can reduce emissions by managing water levels. You have to be careful to not inadvertently create conditions that help reduce methane but increase nitrous oxide production, a potent, long-term greenhouse gas. We don’t want to trade one for the other.

Q: What is MethaneSAT and how could this technology help to lower methane emissions?

HAMBURG: MethaneSAT is a greenhouse-gas-measuring satellite, the most precise of its kind. It was developed following a five-year research campaign started in 2011 to measure methane emissions from U.S. oil and gas production, as we lacked good data. Collaborating with hundreds of scientists, we published numerous studies and a 2018 synthesis article to understand methane sources across the entire sector—the most comprehensive look at methane emissions from any sector anywhere in the world. It was not feasible to keep making these types of measurements, let alone making them around the world.  MethaneSAT allows us to collect continuous, global data quickly, addressing the need for ongoing measurement and understanding of methane emissions over time and space. MethaneSAT was designed to produce the high-quality data necessary to create what I refer to as radical transparency and answer the key questions: where is methane being emitted, how much is being emitted, and how are those emissions changing over time?

Q: What share of methane emissions comes from inland waters?

RAYMOND: Approximately 20%. In the latest Global Methane Budget, we aimed to determine the anthropogenic component of natural fluxes. Our best estimate is that about half of these natural emissions result from human activities. For example, reservoirs are direct anthropogenic sources, while rivers and lakes have components affected by eutrophication due to farm runoff or wastewater, which leads to low oxygen and increased methane production.

Q: What is the Global Methane Budget?

RAYMOND: The Global Methane Budget is a project under the Global Carbon Project involving academics who come together on their own to assess global methane emissions. I’ve been involved with the Global Carbon Project for 15 years and the Global Methane Budget for eight years. We use a bottom-up approach, where different sectors, like stream and river experts, contribute their data. There is also a top-down approach that involves measuring atmospheric methane and determining its source by tracing air masses. This budget combines these methods to provide a comprehensive understanding of global methane emissions.

Q: Are there any promising technologies to capture methane from the atmosphere?

RAYMOND: Direct removal technologies are in the beginning phases but show some promise. Nature-based solutions also hold potential, such as better management of rice cultivation, controlling leaks, managing landfills, and constructing reservoirs in ways that emit less methane.

Q: What can the average person do about the methane problem?

HAMBURG: First, they can recognize the importance of addressing methane issues. Be conservative with fossil fuel use and eat beef responsibly, in quantities that are good for your health. It’s important to be aware of assumptions about practices like pasture-fed beef, which might not always be better than feedlot beef in terms of methane emissions. You can also demand high performance and empirical data from companies, especially in the fossil fuel industry. We need radical transparency and accountability for greenhouse gas emissions, and initiatives like MethaneSAT can help catalyze the required change.

Q: Should we get rid of our gas stoves?

HAMBURG: Personally, I haven’t gotten rid of my gas stove, but over the long term, we need to move away from gas appliances. It’s not always practical to discard working appliances immediately but transitioning to electricity is beneficial for health and reducing fossil fuel use. If I were to buy a new stove, it would not be gas.

Q: What is Yale doing related to methane emissions?

Yale has been actively involved in methane research through various initiatives in Yale School of the Environment and the Yale Institute for Biospheric Studies. Additionally, Yale Planetary Solutions recently granted funds to investigate methane oxidizers, bacteria that eat methane, in ecosystems. This project, led by Peter Raymond and Jordan Peccia, the Thomas E. Golden Jr. Professor and Chair of Chemical and Environmental Engineering, will use geochemical and microbial ecology approaches to better understand methane oxidation.

In addition to research, Yale’s portfolio of retired, verified carbon offset projects demonstrate the university’s recognition of methane’s role in global warming and its commitment to addressing the challenge. Among the projects that offset campus emissions are a livestock mitigation project in East Canaan, Connecticut, and several landfill methane reclamation projects. Read more about Yale’s verified offset projects.