Media Briefings

Methane emissions in the United States

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In the United States, the majority of emissions of methane, a highly potent climate-warming pollutant, comes from the oil & gas and agricultural sectors. SciLine’s briefing covered methane fundamentals, including how it is measured and traced back to sources; the potential for methane leaks from oil & gas systems; the sources of methane from agriculture; and the economic tradeoffs involved in curbing emissions from these sectors. Three scientific experts briefed reporters and then took questions on the record.

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RICK WEISS: Hello, everyone, and welcome to SciLine’s media briefing on methane and climate change. I’m SciLine’s director, Rick Weiss, and for those not familiar with us, SciLine is a philanthropically funded, editorially independent free service for journalists and scientists based at the nonprofit American Association for the Advancement of Science. Our mission is pretty simple. It’s to help reporters like you get more scientifically validated evidence into your news stories. That means not just stories about science, but any story that can be strengthened by the addition of some science, which in our biased view, is just about any story you can think of. Among other things, we offer a free matching service that helps connect you to scientists who are both deeply knowledgeable in their field and are excellent communicators. Just go to the website and click on, “I need an expert,” and while you’re there check out our other helpful reporting resources.

Today, we have three panelists who will make short presentations of up to about seven minutes each before we open things up for Q&A. To enter a question during or after these presentations, just hover over the bottom of your Zoom window as you’ve been doing for two years now, select Q&A, and enter your name and news outlet and your question. If you want to pose your question to a specific panelist, be sure to note that. A full video of this briefing should be available on our website by tomorrow, and a time-stamped transcript a couple of days after that, but if you’d like a raw copy of the recording more immediately, just send a message with your name and email in the Q&A box, and we can send you a link to the video by the end of today. You can also use the Q&A box to alert SciLine staff of any technical difficulties.

To get started, I’m not going to take time to give full introductions to our speakers. Their bios are on the SciLine website under media briefings and under the panelists’ tab. I’ll just say that we’re going to hear first from Dr. Lori Bruhwiler, physical scientist at the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory, who is going to cover the fundamentals of what methane is.

By the way, you’re going to see CH4 a lot out there, so if you don’t know that one by now, CH4 is methane, where it’s coming from, how we know where it’s coming from, and the surprisingly complicated problem of assessing its specific contributions to climate change, especially compared to its better-known cousin, CO2.

Second, we’re going to hear from Sarah Marie Jordaan, assistant professor at Johns Hopkins School of Advanced International Studies, who is going to focus on methane emissions from oil and gas extraction activities, where and how these emissions occur, and the potential economic tradeoffs of mitigating this class of sources.

Third, we’ll hear from Dr. Frank Mitloehner, professor and air quality extension specialist at UC Davis Department of Animal Science, who’s going to talk about methane from agricultural practices, including the role of burping ruminants and some approaches to mitigating this emissions source. OK, with that, Dr. Bruhwiler, it’s over to you get things started. And you’re on mute.

Methane fundamentals


LORI BRUHWILER: Of course I’m on mute. Let me go back here. Now, I’m going to put this into slideshow mode, and here we go. I’m going to start out with the role of methane in the climate system. Let’s look at which gases are most responsible for the excess heat trapped in the atmosphere. We call this radiative forcing, and this graph shows the human impact on the energy budget of the climate system since pre-industrial times.


RICK WEISS: Lori, I’m just going to interrupt you for a moment. I think you’re not in slideshow mode—in presentation mode I mean. If you click on slideshow and then hit presentation mode, I think that’ll do it.




RICK WEISS: See slideshow on the top there?


LORI BRUHWILER: Slideshow, and I’m seeing my slideshow.


RICK WEISS: I’m seeing your full deck on the left and then your main slide to the right.


LORI BRUHWILER: Okay. Let me stop sharing, and I’m going to put my presentation in—well, I can’t do that because then I have to switch back. Let me try sharing again.


RICK WEISS: Okay. We can get by as it was.


LORI BRUHWILER: Okay, I’m going to select the PowerPoint window again. Now, you’re seeing my slide mode, and now I’m going to put it into slideshow. Any change?


RICK WEISS: No, but it’s OK. We’ll focus on the right side of the screen there. At least for me, that’s where your main slide is, so that’s the graph we’re all looking at.


LORI BRUHWILER: Okay. I’m sorry about that. I don’t know what’s happening. Anyway, as I was saying, this figure shows radiative forcing, the human impact on the energy budget of the climate system since pre-industrial times. CO2 is the blue region, and it supplies the majority of the radiative forcing, and its contribution is rapidly increasing. Methane is the green area, and it currently contributes about 16 percent of the total radiative forcing.

You’ve probably heard that methane is a more powerful greenhouse gas than CO2. Global warming potential is a simple way we can compare the strength of greenhouse gases. Methane has a global warming potential of 28 to 36, and this means that over 100 years, a kilogram of methane is 28 to 36 times more efficient at trapping heat than a kilogram of CO2. However, there’s about 200 times less of it in the atmosphere because emissions are smaller, and it’s removed by chemistry.

Chemistry in climate models used for the recent Intergovernmental Panel on Climate Change report, or the IPCC report, provide estimates of how different gases have contributed to changes in observed global temperature. According to climate models, CO2 has contributed about three-quarters of a degree Celsius while methane could have contributed half a degree. Even though its shared radiative forcing is small, methane can have a large impact on temperature because it affects other radiatively-active species through chemistry, such as ozone.

There’s a large spread in the model estimate shown here in parentheses, and this indicates uncertainty. For CO2, this spread is coming from uncertainty in how climate change will interact with things like the natural carbon cycle, clouds, and aerosols. For methane, this spread is due to the uncertainty in the chemistry. Reducing model uncertainty is really important because if methane produces a temperature increase at the high end of the estimates, then we get a larger benefit from decreasing its emissions.

Are you seeing my methane climate feedback slide?


RICK WEISS:  I’m still seeing slide one primarily. You might have to click on your subsequent slides for methane climate feedback.


LORI BRUHWILER: Great. I don’t know what’s going on there.

A concern we have is how CO2 and methane emissions and climate change will interact in the future. We call these possible interactions carbon cycle climate feedbacks, and an example is arctic permafrost carbon. There’s a huge amount of carbon in thawing arctic soils, and some of this is going to be mobilized to the atmosphere as CO2 and methane. How much depends on how much we let the Arctic warm.

Likewise, tropical methane emissions are not well understood, and the area covered by wetlands could change as the climate changes. Feedbacks like these are really important because they may mean that we have to make even deeper emission cuts to meet climate goals. So far, atmospheric measurements suggest that any changes in arctic emissions are too small to detect, but we don’t know how long this will last or when it will change.

So, what do we see in the atmosphere? These plots show year on the bottom axis and observed concentration on the vertical axes, and CO2, on the left, is rapidly increasing in the atmosphere due to our fossil fuel emissions. The picture for methane is more complicated because methane is continually emitted, but it’s also continually destroyed by chemical reactions, so growth of methane affects a balance between emissions and losses. Think of the bathtub, where the tap is emissions, the drain is loss by chemistry, and the water level is atmospheric methane. The water level changes depending on how much water is coming out of the tap or whether the drain is clogged. In contrast to methane, CO2 is chemically inert, and it takes hundreds or thousands of years to be sequestered in the oceans and their sediments. A very, very slow drain.

After a brief period of stability, methane is growing again in the atmosphere, and we don’t completely understand why. We do have a big clue. Measurements of carbon isotopes of methane in our air samples imply that microbial sources – probably a combination of natural and anthropogenic – are to blame. Our model calculations suggest that about 80 percent of the recent increase is due to increase in microbial emissions, leaving 20 percent for fossil fuels. Microbes like to use the lighter carbon isotope, carbon-12, and the figure on the lower right shows that atmospheric methane is getting lighter over time. You’ll have to trust me on this. The units of isotopic composition are really complicated.

This map on the left shows network sites operated by NOAA and other agencies. You can see there are gaps in the network, some at important source regions. On the right, you can see the various way we collect air samples from surface sites to aircraft and tall communication towers. NOAA air samples collected all over the world are shipped back to our lab in Boulder, where we carefully analyze them.

And we can also measure methane from space, but satellites can only see the amount of methane averaged over the depth of the atmosphere with little vertical information. On the left, you see column average methane from the TROPOMI instrument, which is on board the European Copernicus Sentinel-5 satellite. On the right, you see images from a privately-funded GHGSat. TROPOMI allows you to infer where leaks of methane associated with oil and gas production are likely occurring. GHGSat provides much higher spatial resolution, and from this data you can see emissions from individual facilities.

To convert atmospheric concentration information like that we’re showing on the right here to emissions, we need to know something about how emissions are dispersed by the atmosphere. For highly localized cases, we may need only local wind information. To estimate emissions at larger scales, we use regional or global atmospheric models like the ones we use for weather prediction.

On my last slide here, I’d like to show you a methane budget and how it breaks down. The sunburst chart shows a plausible methane budget, and the reason I say plausible is because it agrees reasonably well with atmospheric observations.

In the center, you see that annual emissions are 577 teragrams per year, or a million metric tons, if you prefer. In the next ring, we see that 37 percent of this is associated with fossil fuels, 29 with human-caused microbial emissions, and 24 coming from natural microbial sources. The outer ring breaks things down further. The largest single source is wetlands. Oil and gas contribute 16 percent of global emissions, and 17 percent are from livestock.

So, on the right I have some estimates of how large U.S. emissions are relative to the annual global budget of 577 teragrams based on published literature. The U.S. contributes eight percent to global emissions. Two percent of global emissions are from U.S. oil and gas production. One percent each comes from U.S. livestock and waste. By waste, I mean landfills and sewage. There is a lot of uncertainty associated with these estimates, and if there are questions about that, I’m happy to elaborate during the questions. Thanks for your attention.


RICK WEISS: Fantastic. And I loved the bathtub analogy. That makes things very clear. Thank you for that. And I want to remind folks that these slides will be available pretty much immediately after the end of this briefing, so you can get a closer look at them and get the details. With that, I’d like to go over to you, Dr. Jordaan.

Oil and gas production: methane emissions


SARAH JORDAAN: Hi. Do you see my presentation now?


RICK WEISS: Yes, and I can hear you.


SARAH JORDAAN: Wonderful. That’s good. You warned us about the mute, and then we’re all now doing it. At any rate, thank you so much for inviting me. As Rick said, I’m Dr. Sarah Marie Jordaan. If you want to know more about my research group, there will be links embedded and more links to the other publications that I have that might be relevant.

So I wanted to start off with just a basic question: What is natural gas, and how would methane leak from its production? Natural gas is a mixture of compounds that is found underground, mostly methane, formed in geologic basins. It is used for a lot of energy services today, such as generating electricity and heating homes. So when you turn on the light switch, there’s a great idea about how natural gas might be part of what you use as an energy service.

It can be produced in a number of different ways. One would be conventional, and that would be where a gas well would be drilled and it would be produced from the flow of the pressure that occurs underground. More recently, a lot has been more economically feasible by the combination of hydraulic fracturing and horizontal drilling. So that’s the fracking that we often hear about in the media. It’s also a co-product of oil. And then, it’s called associated gas, and of course there are other ways that you can convert waste to energy, for example through anaerobic digestion.

What we’re going to be talking about is oil and gas infrastructure. So you’ll see in this diagram here you can have either oil or gas wells where you extract from the ground, and then that product will go through a pipeline to a processing facility where the products are actually either separated out from each other and/or there are impurities and sometimes environmentally damaging substances that are removed from the gas. Then, you have post-process gas, which will then go through infrastructure to either the end use, so it’s compressed so that pressure is high enough, and then it goes through pipelines to an end use, where it could be heating homes, et cetera.

Or sometimes, it’s transported over the ocean, and then it would liquefied and re-gasified. And at any point in this, there could be a seal or a practice where methane is released into the atmosphere. So just to take a step back, the reason why we often talk about natural gas or just gas in general is that it occurs underground in reservoirs with a number of different compounds. So you’ll see here on the right-hand side, this is just an example. This is a high-methane gas example, so it has 95 percent methane, and then if you go down there’s other products that you might know about, for example propane, and then other types of gases such as carbon dioxide, oxygen, and hydrogen.

Now, there can be specific impurities such as sulfur compounds, which can have negative health impacts if they are not removed. It can also be much lower percent methane, for example 75 percent, and also it could be associated gas. So that would mean that there would be a large fraction of oil here. So just to keep in mind that of course there’s a lot of processing and steps that natural gas, when extracted from the ground, will go through before it meets the consumer in the form of an energy service.

What you see on the left-hand side is just a small depiction of that where you’ll see the natural gas that’s extracted from the ground. It goes through gathering sites and then it pipelines. The gathering sites will compress the gas so it has high-enough pressure to flow all the way to the processing facilities, and then this would be post-process gas after here. So, it would have a much higher level of methane and other components. And also, the co-products will be separated out and then it’s transported to an end use. And here is an example of electricity generation.

So the reason—you can imagine why it’s really tricky to measure what exactly these methane emissions look like given the fact that there’s a lot of different facilities that are involved with its extraction and transport. So what this figure shows is a comparison of a number of prominent environmental and energy organizations, some of their published methane leakage emissions from natural gas production systems in different countries. So the Environmental Protection Agency, the Nations Framework Convention on Climate Change (their countries report their emissions), and the International Energy Agency.

So, it’s really tricky to measure these and to measure them well. The y axis here is grams of CO2 equivalent per megajoule of natural gas produced. Now, although it’s challenging to do the measurement, that can actually be part of the solution. So the International Energy Agency estimates that 75 percent of the known oil and gas emissions could actually be avoided, and 40 percent could be avoided with no net cost. So there are a lot of different options. Of course, one major one would be better measurement, and that would include abandoned wells. So it’s known that once wells are no longer producing for those energy services, sometimes they’re not appropriately plugged, so they can continue leaking after operations.

But there are a number of other ways to mitigate those emissions, such as replacing existing technologies, for example, electric motors replacing natural gas motors, ensuring that there is better seals. There can also be new devices, so flares would be combusting the natural gas rather than venting it to the atmosphere, although that still results in some level of methane and also CO2, and leak detection and repair programs.

Now, one of the challenges is of course that given all of these differences in emissions, it’s really hard to predict and anticipate where the mitigation opportunities should happen, and it’s also highly variable across facility types. So if you look at the left-hand figure, these are the estimated emissions. Actually, we looked across North America, took a sample, and then improved the estimation techniques, which you’ll see the turquoise, compared to the measurement studies, can be improved quite substantially. In better improving estimates and aligning them better with measurement data, we can really think through more how much the costs compare to mitigate these.

So on the right-hand side, you’ll see that there’s a large difference, a large range in the amount of potential net revenue per completion. That’s the y axis, and that’s because these facilities are really different. There’s a different amount of natural gas that can be captured and sold from these different wells using reduced emissions completions, and it depends on the practices of the companies. So, if you’re ever in a situation where it seems like there’s conflicting information, it’s because it’s a very large infrastructure set, and that experiences a lot of variability.

So in conclusion, methane is a powerful greenhouse gas, 28 times the global warming potential of carbon dioxide over 100 year time horizons and 80 over 20 year time horizons. And it represents a substantial fraction of the natural gas that’s produced from underground fossil fuel reservoirs. It can leak from many places across very complex natural gas infrastructure webs. And while the science is improving, there are a lot of uncertainties that remain. So that really means that we need to focus on improving measurement of what’s going into the atmosphere.

And on top of that, it’s important to remember that it can be very cost-effective and even profitable to capture and sell the methane rather than to release it from the atmosphere. So those large ranges that I showed, actually show on average it can actually result in profits by doing so for this particular technology, reduced emissions completions. And thank you very much.


RICK WEISS: Thank you, Dr. Jordaan, very interesting. I think so much of the news emphasis is on what to do about leaks but maybe not so many stories about how little we know still about exactly how much is coming out and where, which seems like a great area for journalistic inquiry. Um, over to you, Dr. Mitloehner.

Rethinking methane: livestock’s path to climate neutrality


FRANK MITLOEHNER: Yes. Good afternoon, everybody. It’s a great pleasure for me to talk to you today about livestock-related methane. And Rethinking Methane is the title of my talk. Undoubtedly, there is a main focus on contribution of livestock to methane and rightfully so because methane is a significant contributor to that particular greenhouse gas.

The Environmental Protection Agency, EPA, estimates across all sectors of society including livestock and inventories there, and what you see on this slide, on the x axis are the years. On the y axis, CO2 equivalent emissions. In orange, you see at the bottom the contribution of beef. Then, in light blue that’s other animal agricultural contributions. And then, this salmon color is largely the fossil fuel sector. That’s transportation, hog production use, cement industry, and so on.

So while this might look like a sliver to you, all of animal agriculture is about four percent of direct emissions in the United States. And that means, direct emissions means belching and animal manure emissions. In the case of vehicles, it’s largely tailpipe emissions. Four percent might not sound too much, but it’s quite a chunk. The dairy and the beef sector each contribute approximately two percent of total U.S. emissions.

So as Dr. Bruhwiler said, methane is a different kind of greenhouse gas insofar that it’s not just produced like others but also destroyed. Remember that bathtub example that she gave. And that bathtub example really exemplifies why there are differences in how these gases, let’s say gases like CO2, carbon dioxide versus methane, CH4, how they behave and how they warm the planet.

What you see on this slide are three scenarios that I’ll go through one-by-one. The first one is rising emissions, then constant, then decreasing emissions. On top, you’ll see the actual emissions of CO2 and methane from two sources. It could be a power plant versus a cattle herd. When both go up, then you see at the bottom that the related warming also goes up, but for CO2 it goes up exponentially. It goes up higher because CO2 accumulates, whereas methane is not just produced but also is destroyed. So, if methane goes up, the related warming goes up, but if you have constant emissions of both CO2 and methane on top here, in the second panel, then the related CO2 warming goes up pretty strongly, whereas the methane is stable.

That is because methane is not just produced but also destroyed. That’s the bathtub having an open drain, okay. So, if we put a constant amount of water into that bathtub and we drain an equal amount that means constant warming. But what we’re really all after is to further reduce emissions. That brings us to the third scenario, which is, what happens when we reduce CO2, let’s say from power plants, as well as methane from, and let’s say livestock herds.

Surprising to many, the warming from a reduced CO2 over time continues to increase up until the point where we get to net zero emissions. So only at the point of net zero emissions for CO2, we reach a point by which CO2-related emissions plateau in warming. But look what happens when you reduce methane. You get an instantaneous negative warming. Some people call that cooling, which is a, of course, a strategy that we should deploy. That includes, of course the livestock sector. There is some discussion about how to quantify the impact of methane on warming and how—what metrics to use, but I can’t get into that in the interest of time. You’ll see here some links mentioned on my slides.

What I encourage the livestock sector to do is to continuously reduce methane because if we do reduce methane, in the case of beef by 18 percent, in the case of dairy by 32 percent here in the United States over the next few decades, then we will achieve a point by which both dairy here in blue and beef in orange reach a point by which emissions, warming-equivalent emissions, hit this x axis. That means we no longer contribute additional warming to the planet. In fact, at that point we eat into historic emissions and reduce those.

And so that is the point of reaching climate neutrality. If we reduce methane by enough, then we are inducing what I show on this slide here, negative warming, and that’s where we want to go. Negative warming on the methane side will offset some of the other emissions of nitrous oxide and CO2, and that can get us to a point of climate neutrality, not carbon neutrality but climate neutrality. We might also call that net zero warming. So that point can be achieved by annual reductions of anywhere by half a percent to one percent, and if we achieve those one, approximately one percent reductions annually, we reach climate neutrality by approximately 2045.

How can that be achieved? Here in California, we have a new law that mandates a 40 percent reduction, four zero, of methane. Our dairy industry has aggressively worked to achieving that. Even though it started three years ago, many dairies have gone ahead and covered their manure storage lagoons. You see here one covered lagoon, and what happens underneath this cover is that biogas, 60 percent, six zero, of which is methane, accumulates. It’s not a lot going into the air. It accumulates, and this biogas is then used to produce fuel. This fuel is called RNG, renewable natural gas. This fuel then goes into vehicle fleets such as semi-trucks.

You see here a depiction where dairy biogas is converted into RNG, into this fuel which then replaces diesel from vehicles. So, these trucks are now not run on diesel. They’re now run on dairy RNG. So, by that strategy alone we have already reduced 30, three zero, 30 percent of dairy methane emissions in the State of California. That just started a few years back.

So, that’s not the only, it’s one main avenue but not the only one. The other one is the use of feed additives to reduce what’s called enteric emissions. That’s the belching of animals. Here, you can see on the left various feed additives one can feed to both beef and dairy cattle. These additives can reduce methane from those animals by anywhere between 10 to 50 percent. Unfortunately, of all of those, only one is commercially available yet. The other ones are still in the experimental stage but will be in about five years from now.

So, the bottom line here is livestock agriculture, when reducing particularly its methane can be part of the climate solution because reducing methane has a really good impact on climate. Reducing methane is possible, not just for manure, but also from belching as well as through improved field management to increase soil carbon sequestration. With that, I thank you very much for your attention, and I’m looking forward to our discussion.


What are some science-backed tips and pitfalls-to-avoid for reporters covering methane emissions?


RICK WEISS: Thank you, Frank. Very interesting—I’m so curious to hear whether cattle like eating seaweed or oregano I see on the list here, too. Maybe they’re pizza fans. We’ll perhaps learn more about that in the Q&A. Interesting approach to reducing methane from belching. With that, we want to get into the Q&A phase here. I’ll remind reporters that you can click on the Q&A prompt or icon at the bottom of your screen and submit your questions.

In the meanwhile, I like to start these briefings with one question from the moderator and ask each of our panelists to address the question of—from their perspective and the work they’re doing in the methane arena and reading news stories as they do all the time, is there something you can tell this group of reporters that either you’re impressed by in how the reporting is going is going in this field or areas that you think would be ripe for improvement and give some advice to reporters covering this beat? I’ll start with you, Lori.


LORI BRUHWILER: Well, the first thing I want to say is my brother is a journalist, and he’s written for newspapers. I have a deep respect for the hard and important work that journalists do. My answer to this question, it has to be my personal opinion. It’s not a technical question, and so I just want to say that. What I worry about in terms of methane reporting is that I wonder if the perception out there is from reading what has appeared in the news is that, a) There is a climate catastrophe taking place in the arctic with methane emissions being dumped out by strange and disturbing processes.

That’s one thing that has come up for me, and I think that that sort of thing can be solved if only people get a more varied perspective, consider what has passed peer review. I know you guys, you reporters know about peer review and you try to be careful, but this is just one problem I’ve seen. Another problem is that people may have this perception that methane is all about oil and gas, and if only we fix oil and gas leaks, we will be in good shape in terms of climate change.

Yeah, methane is, as we’ve been hearing, a really important tool for confronting climate change, but it’s not by itself sufficient as I think some of my material has shown. And so, that’s my perspective, and I think forums like this one are really valuable at maybe improving the communication. I mean it’s not all the journalists exaggerating things. We scientists exaggerate the importance of our work, and we also sometimes fail to have the global picture. So, that’s my take.


RICK WEISS: Thank you, Lori. Sara?


SARAH JORDAAN: Lori, thank you for that, too. That was a lot for me to chew on as I’m thinking through my answer. I want to take a quick second to say I actually—maybe I’ve been fortunate, but I’ve actually found reporters on my research, for example, to really stick to the facts. Quite often, I’ve noticed that in a number of other reports as well. It could just be the news that I gravitate towards, though, so there could be a personal bias in there.

There’s two things that I think that are really tricky. It’s tricky for us, too. This is why I’ve spent a time, I’m sure, about how to communicate to the media. One of them is uncertainty is really difficult, and I don’t know how we can explain that better to the public. Uncertainty in climate science is often used against it, and so I think it’s important that we contextualize uncertainty and variability correctly so that the scientific facts are the scientific facts. That’s one thing that I’d like to point out, and it shouldn’t be used against science.

Uncertainty is actually one of my favorite things about science. The fact that there’s variability in those numbers doesn’t mean that it’s a bad thing or anything else. It just means that it actually is the source of some disagreement about specific aspects, and then it becomes political because I work in oil and gas, or in energy. I don’t work in oil and gas pertinent to what I’m talking about today.

Now, on that token I think it’s also very important to make sure to engage from all sides. I’ve seen many reporters do it really well, so I wanted to emphasize it. For those aspects that are very political, so for an academic like me who has part of her research in oil and gas, it is immensely political, and it makes it really tricky. So, to ensure that you get all sides is, I think, really critical, so environmental organizations, engaging politicians and regulators so the public understands a little bit more what exactly is being done.

I think a lot of the time it’s confusing what’s being done and what’s not being done. Even criticisms of the EPA’s emissions inventories; there’s still a lot of confusion in the academic community that they’ve actually improved a lot. They’re actually improving them every year, and for some reason I’ve run into criticisms all the time, but they’re actually updated according to this really great, recent research published by Harvard. So, staying up-to-date is important in getting all sides. That would probably be about it. I don’t want to take up any more time, but I’d just like to emphasize again I’ve seen a lot of very good reporting, so that’s a positive thing.


RICK WEISS: Great. Thank you. And Frank?


FRANK MITLOEHNER: Yes. Recently, I saw an interesting work by Carbon Brief, an article that looked at what would happen if 105 countries that have pledged a 30 percent reduction of methane were to achieve that. What would happen to our climate? What they concluded was that it would lead to a 0.1 degree decrease in warming. While that doesn’t look like much, it’s still something, and it’s something that every sector that emits methane needs to help with, but it would not replace, and it’s not even close to the fossil fuel part of the story. That’s, in my opinion, the 800 pound gorilla that we should not be sidetracked on.

There’s one thing that I want to mention, and that is that I’m oftentimes frustrated by seeing in the media reporting on global livestock emissions, which are high, 14.5 percent. Then, it’s suggested that livestock emits so much, and therefore we need to eat less or produce differently and so on, but the needed nuance is not offered, namely the nuance of that in different parts of the world production of livestock is very different. Technology use is very different, efficiencies are very different, and that nuance is needed in order to treat those farmers fairly.

What is the carbon impact of bio-methane produced from existing waste sources?


RICK WEISS: Great. Yeah, the international versus domestic story on livestock is quite different, and I think as you’ve hinted at, at least in your presentation, I think livestock populations are stable in this country for quite a while now. So, that’s a different picture. All right. We’re going to move to some questions now, and the first one is from Bryn Nelson, a freelance reporter based in Seattle. Can one of the panelists talk about whether bio-methane produced from existing waste sources such as anaerobic digesters at wastewater treatment plants is carbon neutral or perhaps even yields a net reduction in some cases?

Some accounts suggest that the CO2 soaked up and released by plant biomass cancels out but that the net CH4 emissions are less. Does anyone have enough experience to address that specific?


SARAH JORDAAN: I can provide a bit of an answer. With anaerobic digestion, much of the point is to actually—in the designs that I look at, I do circular economy, and it’s all about waste reduction for anything that involves this type of chemical. The idea would be to use the product so that the methane that comes out for energy, so more of a waste-to-energy type of structure. Because of that, you can imagine that if you’re sourcing biogas rather than gas from natural gas—oil and gas production systems, you can imagine that there is a lot fewer opportunities for gas to be released in the infrastructure systems. Regarding the plants and the biomass, it’s a very complex question because it’s going to be highly dependent on what the input feed stocks are. Of course, it’s organic matter, so anaerobic digestion can have a lot of different feed stocks.

What is the commercially available feed additive that reduces methane emissions in livestock?


RICK WEISS: So, this is an “it depends,” it sounds like. OK, a question here from Tom Heap, a freelancer based in San Francisco, for Dr. Mitloehner. What is the commercially available feed additive that you mentioned?


FRANK MITLOEHNER: The name of the product is Agolin, and it is an essential oil. Most of those products that I showed on my slide are so-called natural feed additives, so things such as oregano or garlic extract or essential oils or tannins. The only one is Agolin right now. The other ones are not commercially available, but in my opinion will be in the next five years. We have really seen some great results. Not just do these things reduce methane, but in many cases they improve performance of animals because methane losses are also a net loss to performance because a cow loses about 10 percent of its energy off the feed energy through methane. So, it’s in the best interests of the farmer to minimize methane.

What is the percentage of methane in biogas?


RICK WEISS: Hmm, interesting. Just while I’ve got you, Dr. Mitloehner, another question from Steve Davies from Agri-Pulse, just wanting to catch the percentage of methane that you mentioned in biogas. He missed that.


FRANK MITLOEHNER: Six-zero, 60 percent of biogas is methane, and then there are impurities in there. There’s a lot of hydrogen sulfide in there that needs to be cleaned out for biogas to become renewable natural gas. Sixty percent is the methane.

Rice agriculture is a major source of methane; are there strategies to reduce the fermentation that occurs in rice paddies?


RICK WEISS: Okay, a question for Dr. Bruhwiler; it’s surprising that rice agriculture is a major source of methane. Are there strategies to reduce the fermentation that occurs in rice paddies?


LORI BRUHWILER: I have heard of some strategies involving how you apply nutrients and whether or not you drain the rice paddies at certain times of the year. Those things help. There’s an interesting anecdote actually about rice. I was looking at the world production statistics recently, and for a while rice area under cultivation—and  that’s what matters in terms of methane emissions—because they’re like swamps and wetlands. So, it’s the area that matters for the emissions. Well, for a while the international statistics showed that rice area cultivation had leveled off. Recently, that changed.

I was wondering, how could it change? Because I thought we were really cultivating what we had available to a large extent. It turns out that there have been collaborations between China and Africa, and now there’s new rice growing activities in Africa. It’s fascinating, but yeah there are some approaches we could take to reduce rice emissions. I think we have to remember that rice supplies a huge amount of the world’s calories, maybe not in the U.S., but in other places people are really dependent on rice. And as population grows, that is one type of emission that maybe will also grow.

Where can reporters go to get a more accurate picture of methane emissions from the oil and gas industry?


RICK WEISS: A question for Dr. Jordaan from Judith Kohler at The Denver Post; I cover energy and I hear from environmentalists that methane emissions from oil and gas are on the rise. The industry says it’s doing more to stop leaks and emissions are decreasing. Where do I go to get a more accurate picture?


SARAH JORDAAN: This is a really great question. You have just precisely indicated exactly why this is so political. It is really hard to get down to exactly what the right numbers are, which is why I’m just going to take a minute to point out how important it is that there are currently increasing numbers of global initiatives like the International Methane Observatory that are seeking to actually combine what these measurements are. Even some of the best measurement studies, they become outdated very quickly. So, I’m going to give two sides of the answer.

One side is I would strongly recommend credible science from independent institutions, universities. Also, the Environmental Defense Fund is doing a series of studies which have been really valuable in bringing a lot of information forward about the emissions to the public. So, I would check out to see what the recent studies are there. I know that in Colorado, there’s certainly NOAA has been doing some work as well. Do keep in mind, I’m going to be very honest. I have an upcoming publication coming out in Environmental Science & Technology with the best information, and a lot of this is updated according to academic, scientific studies. A lot of the newest Environmental Protection Agency numbers are actually reflecting in some cases decreasing emissions from the industry as they apply more mitigation options. Those mitigation options that I showed you, some certainly are being applied, but I would suggest that you are correct in triangulating the information with the best available studies that you have on the ground in your local areas.

Are there plans for the use of satellites to provide more precise measurements of methane in the atmosphere?


RICK WEISS: I believe there’s more satellites coming in the years ahead that will do some more precise measurements as well.


SARAH JORDAAN: That’s a big—I’m also interested in Lori’s perspective on this because when I see those, I actually, my first question is, well, what about the vertical atmospheric column? I do a lot of facility, ground-up emissions, which has its limitations because of the variability, and then the atmospheric emissions have challenges because of the duration and also fluctuations in the atmosphere, amongst other things. The satellites seem like they’re a few years off. I don’t work directly with the satellite measurements, but I don’t know it, Lori, you want to add something.


LORI BRUHWILER: Well, there are some challenges, and you’re right about the vertical column. We don’t see what’s going on near the surface as well when we look at the vertical column, but the advantage of the satellites is that they’re taking data very frequently and they’re coverage is so well. If you think about how NOAA and other institutions quantified emissions from oil and gas fields that was flying airplanes around and knowing how much methane flows into the field, how much is coming out. Subtract that, and you get the emissions and so forth, the mass balance approach.
How often can we do aircraft campaigns like that? Maybe we should do them periodically. We learned a lot by doing those campaigns. That’s what told us that our inventories needed to be adjusted upwards, and the EPA has done that. Another thing I would caution people against, though, is knowing who you’re getting your information from. There’s advocacy organizations, and the EPA— not the EPA, the EDF is an environmental advocacy organization. We need to take that into account when we are reading their material and assessing their results. They have very good intentions, of course, but it’s something to keep in mind.


SARAH JORDAAN: I’m just going to add to that, too is that’s why I was emphasizing the importance of triangulation because the industry is doing, they are doing things, companies are doing things to reduce emissions, but there still are challenges. I do a lot of the ground-up facility level emissions, and I try to quantify variability to get a good idea from that level, hey, how come these aren’t aligning perfectly? So again, I would just encourage triangulation of the best information possible and again being correct in questioning and ensuring, getting all of those data points from different organizations.

What is the difference in international versus domestic livestock production regarding methane?


RICK WEISS: Okay, a question here for Dr. Mitloehner. It’s from Barbara Moran from WBUR public radio in Boston. What’s the difference in international versus domestic livestock production regarding methane? Don’t cows burp the same everywhere?


FRANK MITLOEHNER: No. Well—yeah, they do burp everywhere, yes—but let me give you a little comparison. In the United States, we used to have 25 million dairy cows back in 1950. Today, we have 9 million. We went from 25 to 9, but with the 9 million today we are producing 60 percent more milk. The carbon footprint of a glass of milk has shrunk by two-thirds over that period of time. So, now we have nine million dairy cows in this country. In India, they have 300 million dairy cows—dairy cows and buffalo. And they are producing a fraction of what we produce with our dairy cows. So, now you wonder, well, why can that be? Well, one of the reasons is that once because cows are holy in a country like India, after they are done milking, after they no longer produce milk, they are cut loose and they are just let go. They just wander around and eat and excrete and emit but don’t produce milk. As a result, you have enormous herds. These are called idle animals, animals that live and emit but don’t produce food. You find them in many parts of the developing world. The IPCC estimated that developing countries throughout the world and their livestock produce 70 to 80 percent of all global livestock emissions. So, this is not some finger-pointing. This is just saying that the lack of efficiency in food production of these animals leads to a very significant environmental footprint. If we want to reduce global livestock emissions, then we really have to help those countries becoming more efficient. Otherwise, those herds will grow and grow and grow.

Are methane releases at Liquefied Natural Gas (LNG) import/export facilities being monitored?


RICK WEISS: Interesting. A question here from Mary Landers from The Current in Savannah, Georgia. Is anyone monitoring methane releases at LNG import/export facilities? Is that worth looking at locally in an area where there is no fracking but there are pipelines and an LNG facility? Is that a potential local news story?


SARAH JORDAAN: Actually, I would argue that yeah, absolutely. The reason why is not because I’m going to over-emphasize. I actually have looked at the liquefaction emissions as well, and what we know about them is that they’re not a huge contributor to the overall life cycle, but the thing is that again, the operations are actually changing. And what happened is that a lot of the early estimates were based on the environment impact statements, so there’s not a lot of really great public data out there talking about the ongoing operations, particularly since there is such an exponential growth in LNG export.

So, I personally feel that showing that it’s greater or less is useful, and it’s something that we need more information about and we need verified with measurement because again, the environmental impact statements are useful, but it’s the operational measurement that I really seek to integrate within the studies. I haven’t seen a whole ton of really great information because, again keeping in mind that the growth in LNG export has been really in the past five or six years. It’s grown substantially, so I suspect there will be a number of studies coming up. I would say it’s not just the liquefaction. The other thing that my group has had to make estimates on is actually transport on the ship.

So, how can we verify how much, if anything is at the ship? And then also, as the ship arrives at the port, that actual operation of unloading the natural gas, the re-gasification, and the other thing that’s lacking is the distribution on the other side. There are data gaps, and I would argue that even from a reporting standpoint, it’s actually useful to even point out what information is not available. Obviously, that can be really useful and an important part of our knowledge of the system and the associated emissions.

Is regulation slowing down the validation and circulation of new supplements for cattle?


RICK WEISS: Interesting. Question from Barbara Pinho, a freelancer in Alabama; on policy, is regulation slowing down the validation and circulation of cattle supplements in additives?


FRANK MITLOEHNER: Is cattle regulation slowing it down?


RICK WEISS: Or any kind of regulation slowing down the validation and circulation of these new supplements? Do you get the sense that there’s roadblocks there?


FRANK MITLOEHNER: There are some roadblocks there because there are certain additives that require FDA approval, Food and Drug Administration approval, and that approval process takes forever in the United States for a good reason. I mean we don’t want to add anything that’s unhealthy to human nutrition, but if you think about what we’re adding there – garlic or coriander or so — it’s not likely that any of that will impact food safety. There are some additives, such as one of them is called 3-NOP that has to undergo FDA approval. This will take four, five, or six years. The rest of the world is already using it. Their approval processes are much more streamlined in other parts of the world, and that really hinders us.

Are satellite images of leaking gas facilities available on public access website?


RICK WEISS: OK. A question for you, Lori, from Tom Heap, freelance reporter; can we see those satellite images of leaking gas facilities, disused or current, on public access websites?


LORI BRUHWILER: What an interesting question. I assume you’re talking about the GHGSat data. That is a private enterprise, and their business model is to sell analyses of their images. That is kind of an interesting thing to think about. You could imagine, for example, that a producer buys that data and it’s never becoming public, so you would never know. This is the motivation, I feel behind the EDF’s launch of their own methane satellite. That data will be, all the analysis will be made available to everybody. TROPOMI is not, that other European instrument, that’s not widely shared yet, either. The U.S. government has purchased some of that data and works with it.

This gets to one of my big issues is international data sharing. We share data internationally to do weather forecasting. We need to start sharing all of our data for the climate problem, too because emissions affect everybody everywhere, and it’s a big problem we need to solve.


SARAH JORDAAN: Could I just add? Just again to highlight the International Methane Observatory because it is a collective, and they are planning to integrate not just the satellite imagery but the other data sets, too, because myself and my group, we go through all of the international data sets and everything we can find. There are challenges with the alignment. The prior studies that we have done, my group has done, show that we need to have a better understanding. You can then improve estimation, and then really ultimately get to the bottom of some of these mitigation technologies and better predictors and the rest of it so that we can actually start to solve the problem.


RICK WEISS: I wonder, Lori, if the price of buying those things from GHGSat, for example, was that the kind of price that only an oil and gas company can afford, or could a news organization afford it?


LORI BRUHWILER: I don’t really know how much it costs, but clearly the TROPOMI people, either for P.R. reasons or because they purchased the data, were able to put that image that I showed in my presentation on their website. So, I can’t comment on that right now. I don’t know.




LORI BRUHWILER: I know NOAA probably couldn’t afford it.

What are some questions reporters should ask oil and gas facilities about steps they are taking to reduce emissions?


RICK WEISS: I’m going to try to squeeze in one or two more questions here. We may run just a couple of minutes past 3:00 for reporters who are hanging on here. A question from Toby McIntosh from the Global Investigative Journalism Network; what questions would you ask oil and gas facilities about steps they are taking to reduce emissions? Great reporting question there—what would you want to know about what oil and gas facilities are doing to reduce emissions? Any sense there?


SARAH JORDAAN: Yeah, this is a great question. Now, I’m just thinking if I could have all the information possible, the first thing that came to mind actually was I think it would be really interesting to have a better idea of what exactly is coming out of each well and then mapping that better with what we know about the emissions and the most effective mitigation technologies. The assays are what comes out of the well. That product suite, or that product slate is not well-known. It’s actually really important for environment, not just climate change but other environmental aspects.

So, I think that would be really valuable for mitigation of climate as well as other potential impacts. And then, certainly more clarification on the actual costs associated with the technologies that are being deployed because that would enable us, as independent researchers, to do better jobs of actually estimating the costs of broader-scale mitigation efforts across oil and gas operations domestically but also globally. Those would be the two things I would suggest. Oh, last one—if we’re asking anything, obviously domestically it would be to get a better idea of regional variability as well as again those influences on costs.

What are emissions like from trucks that use renewable methane-derived fuel?


RICK WEISS: Okay. Maybe a last question here before we do a wrap-up together, but for Dr. Mitloehner; do you have any information about the emissions from the trucks using the renewable methane-derived fuel?


FRANK MITLOEHNER: Yes. The comparison would always be, what is the status quo? The status quo is that trucks burn diesel and then those emissions that result are well-known. Compare those emissions versus the RNG emissions. The RNG emissions have a lower carbon footprint. They have a lower emission spectrum, and so overall that is the reason why this whole technology is incentivized the way it is. Because not just are we reducing carbon intensity by using this fuel, but we are also reducing emissions. That’s why the various agencies in the state are incentivizing it like nothing else that’s out there.

What is one key take-home message for reporters covering methane emissions?


RICK WEISS: Great. All right. I do want to wrap this up as close to on-time as we can, so I want to make one last round here and ask each of you, just very briefly, if you’ve got one take-home message, if there’s one thing you want reporters to walk away with today that they can take with them and maybe build their work around, what would you tell them? I will start with you, Lori.


LORI BRUHWILER: Well, based on my presentation I would like people to walk away knowing that methane comes from a lot of different things that we people are doing, from producing energy to producing food and then disposing of the resulting waste. So, there’s a huge spectrum of things we do that affect methane. And then land use. We can affect natural emissions if we drain wetlands and so forth. It’s a complicated system. It’s fascinating, also.

The other thing is, let’s not forget that if we want to meet climate goals, CO2 is our big problem. We can make a little bit of progress with methane, but let’s not kid ourselves. We will have to confront CO2, and so those are the two big things for me.


RICK WEISS: Very clear. Thank you. Dr. Jordaan?


SARAH JORDAAN: Actually, that aligns very nicely with my answer as well. Climate change is a major global challenge right now, and methane is a large contributor. I would argue, I would agree with Lori about CO2 being a major aspect as well. Of course, these emissions are released associated with different products. It can be oil and gas or other decisions that you make, so I wanted to remind the audience that really we can all play a part in the solution. Our decisions about consumer products day-to-day all really matter, and also making sure that we’re educated, which again emphasizes the role of the reporters in terms of educating the broader public so we actually understand the challenges. So, just a quick thank you to the reporters who are doing so, and also just again emphasizing the impacts of our choices in what we do.


RICK WEISS: Thank you, and over to you, Dr. Mitloehner.


FRANK MITLOEHNER: I just wanted to say that it’s important to understand the nuances around methane. As we discussed, methane is not just produced but also destroyed. But if in addition to that we further reduce it, we make methane into a really important solution for vehicles. And farmers and foresters are really the only two major sectors in society that can pull methane out in a major way. I would incentivize them to doing so. I think it’s really important to view these sectors as one way of helping us have a short-term climate solution. I want to leave it with that.


RICK WEISS: I think that’s so interesting. We hear a lot about carbon sequestration and all the technologies needed to pull CO2 out of the atmosphere, but it’s an interesting reality that simply by reducing methane we actually pull carbon out of the system. It’s a great piece of the puzzle it seems to me.

I want to thank our panelists today for providing so much information to us. For the reporters on, I encourage you, as you log off to take that extra 30 seconds. It’s very helpful to us if you would answer a three-question survey that will be prompted in front of you. We really appreciate your feedback and your help on that. We also encourage all of you to follow us on Twitter @RealSciLine and check out the SciLine website. Thanks all of you for your work in this area and for your attendance today. We’ll see you at the next SciLine media briefing.

Creative Commons LicenseThe text and video on this page are licensed as Creative Commons CC BY-SA 4.0. Journalists are free to use any text or video on this page with or without attribution to SciLine.

Dr. Lori Bruhwiler
Physical scientist, National Oceanic and Atmospheric Administration

Dr. Sarah Marie Jordaan
Assistant professor, School of Advanced International Studies, Johns Hopkins University

Dr. Frank Mitloehner
Professor and air quality extension specialist, University of California, Davis

Video: high definition

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Video: standard definition

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Panelist presentation: Dr. Lori Bruhwiler

Methane fundamentals


Panelist presentation: Dr. Sarah Marie Jordaan

Oil and gas production: methane emissions


Panelist presentation: Dr. Frank Mitloehner

Rethinking methane: livestock’s path to climate neutrality