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November 5, 2024
Atmospheric satellite data can provide key information about climate change, including measurements related to the ozone layer, air quality, methane, and more. In today's episode, Dr. Pieternel Levelt, a scientist and associate director of the National Center for Atmospheric Research, joins Daniel and Alison to talk about satellite instruments like OMI (the Ozone Monitoring Instrument) and TROPOMI (the TROPOspheric Monitoring Instrument). These instruments provide essential data to scientists and policymakers all over the globe.
Show notes:
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Episode Transcript:
Daniel Bresette: Hello and welcome to The Climate Conversation. I'm Dan Bresette, president of the Environmental and Energy Study Institute.
Alison Davis: And I'm his co-host, Alison Davis.
Dan: We're both very excited for today's episode, not just because we have a fantastic guest, but also because we're recording this episode in person at the EESI office. We've done episodes where it's just been me and Alison, and then our guest has been on zoom but believe it or not, eight seasons in, this is our first one where we actually have the guest in the room. So this is an exciting first, and Alison and I have been chomping at the bit to get to this conversation today.
Alison: So since our guest made the trip to be here with us, I hate to keep her waiting through a long introduction. So we're just going to dive right into it. Today, we're talking about atmospheric chemistry and the satellite instruments that are used to study it. Satellite data can tell us a lot of information about climate change, including measurements related to the ozone layer, air quality, environmental monitoring, emission levels and even health impacts. Some of the instruments we'll be talking about include OMI, the Ozone Monitoring Instrument and TROPOMI, the TROPOspheric Monitoring Instrument.
Dan: Our guest today, Dr. Pieternel Levelt, is a scientist and Associate Director of the National Center for Atmospheric Research, or NCAR, where she leads the atmospheric chemistry observations and Modeling Laboratory. Dr. Levelt previously served as the head of the R&D satellite observations department at the Royal Netherlands Meteorological Institute, while also serving as a professor at Delft University of Technology. She is a scientific initiator of the Dutch/European Space Agency's TROPOMI instrument and principal investigator of NASA's OMI instrument, both of which provide essential data to scientists all over the globe. In April 2021 Dr. Levelt was appointed Knight of the Order of the Netherlands Lion for outstanding research in the field of remote-sensing of the Earth's atmosphere composition. She has a master's degree in physical chemistry and a PhD in physics, both from the Free University of Amsterdam. Pieternel, now welcome to the show. It's really nice to meet you today.
Pieternel Levelt: Thank you. I'm very excited to be here, and I'm looking forward to your questions.
Alison: So first, a lot of conversations about man-made global warming and climate change usually focus on new greenhouse gasses like carbon dioxide, but your OMI satellite is actually tracking nitrogen dioxide. Could you explain the connection between the amount of nitrogen dioxide in the atmosphere and greenhouse gas emissions on the Earth's surface?
Pieternel: Yeah, so the ocean military instruments measure nitrogen dioxide, and nitrogen dioxide is an air pollutant, and it's released when you have fossil fuel burning, so it will then be co-emitted with carbon dioxide. There are many more sources where you can have this co-emitted, but let me use fossil fuel burning as an example. So when you have fossil fuel burning, for cars, for industry, for power plants. And if you then have a NO2 release with that, and also CO2 is released, you can lay relations between the amount of nitrogen dioxide and amount of carbon dioxide. So this is actually something which only started, I think, a couple of years ago, that we start to try to make those relations between nitrogen dioxide measurements from space, and try to make estimates based on that, also for carbon dioxide. It, of course, depends on the exact fossil fuel burning process, what this relation will be. So it sounds easier than it is, but when we would be successful, it would basically mean that you can use the nitrogen dioxide measures from OMI. We have now 20 years of those backwards in time to also get the carbon dioxide emissions from this fossil fuel burning. So anthropogenic, human made processes, which, of course, you have to distinguish with whatever there is for natural CO2.
Alison: The TROPOMI satellite has built on a lot of the capabilities of the OMI satellite, including detailed coverage of methane, which will be a major topic at COP29, the annual UN conference happening in Baku. What do you see as the most impactful revelation about methane that this technology has uncovered in recent years?
Pieternel: Yeah, so TROPOMI covers all the same trace gasses as OMI does, but we added two channels, and one of them measures carbon monoxide, which is actually released, for example, for biomass burning or wildfires and its methane. And then we saw the first measurements from TROPOMI of methane. Well, it was mind blowing, I must say so, because we are able, with TROPOMI, to measure methane globally every day, and we measured over land, not over ocean. As soon as there is cloud interference, we cannot achieve it, but still, there are so many more measures of methane from polar satellites than ever before, and that really enables us to get an overview of all these different methane sources. So that's not only oil and gas winning, but it's also wetlands and landfills. And we can really now measure these emission sources, because we have a mapping mechanism. So a previous instrument, which is very good and still there, and to which we also use a lot in our community, is cosets, very accurate, but the mapping potential of TROPOMI, where you really have a global view every day. That's exceptional. So that is something which really will enable us to get much more information of all the different emission sources from retailing which are man made, but also on a natural basis. The second main win TROPOMI showed, is that when there are large unplanned releases, for example, from the oil and gas industry, we can measure that with TROPOMI. So we see this plume of meeting coming from that release. And there have been several examples of that, and the first one was Turkmenistan oil and gas release. And also in Algeria, we see these big plumes, and there are more locations. So TROPOMI showed us that we actually can measure this from space, and in combination with that, we have now a lot of new small sets that measure very, very high resolution, but never can obtain data global coverage, who can now measure that even better. So that completely changed our view of what we can do from space.
Dan: That is super interesting. Pieternel, before we started recording today, you were talking to us a little bit about what you're doing in D.C. this week, and you've got lots of meetings, and sounds like many of your meetings are about current technologies and current capabilities, but also what you would like to see come down the pike with cooperation between the US and NASA and ESA and Europe. What are some potential or emerging applications of satellite technology brought to us by NCAR that you would like to see come to fruition over the course of the next decade, to allow your work and the work of your colleagues to take the next step?
Pieternel: So the instruments I just talked about, OMI and TROPOMI, have a Dutch heritage. OMI flies on a NASA satellite. But also the lab I'm currently leading, which is NCAR in Boulder, Colorado, we use satellite data to understand air pollution and climate and we have a few satellite instruments which we are strongly involved in. And in my lab, one of the instruments is called MOPITT. And MOPITT measures carbon monoxide, and that is a very important trace gas which comes free with wildfires and biomass burning. So technology we developed for that, similar technology can be used, for example, to also measure methane and CO2. We are now advocating, as I told you when we met each other, for measurements over the global south. That is focused on air pollution and air quality, but also measurements on greenhouse gasses would be very, very important, potentially. And the technology we have at NCAR could develop instrumentation for that. We could measure that, and then we are thinking more about having instruments in geostationary satellites over Africa, for example, so that you have several measurements a day. And that is important for many reasons. One is that there are not many measurements over the Global South, but also because some of these sources, like methane, change over the day, so there's lots of constant sources during the day. So when you're measured in the morning, then you know what is going on the rest of the day, but that can change over the day. And due to that, you want to follow these tensioned emissions, as we call them. And for that, you would use the assessment satellites. So that's one. The other one is more related to the Ocean Bay and Montreal Protocol. So we have another instrument in my lab that basically flies together with my OMI instrument, but it's not functioning anymore because these instruments are built for five years and only are exceptional over 20 years, but not every instrument reaches that timeline. And that type of technology can actually be used to really measure accurately the ozone layer and the trace gasses that destroy ozone, and we have an instrument currently in place at NASA, but that will also stop in two years from now, and there's an urgent need to have new satellite instrumentation to measure the ozone layer and the trace gasses that destroy ozone, especially in the time of climate change. And so we are strongly involved in a new initiative for that which is not yet selected in the final stage by NASA. And that instrument is called strive, and that uses the other technology, because we have a lot of expertise in that NCAR.
Dan: Well, I know the global south is important to you and your team, and so I'd like to go back to that point, because I think it's really interesting and probably something that our audience may not realize. Just the disparity in measurements, there's just far less data, severe lack of measurements for climate and air quality in the Global South, and those are also happened to be, for the most part, the countries that have contributed the least to climate change by emitting lower emissions than countries like the United States and European countries and China, but they're disproportionately impacted by the impacts. How are you and your team at NCAR advocating for better satellite observations of the Global South, and what would the benefits be, not just to people who live in the Global South, but to the global community, to have better information about what's happening there?
Pieternel: Yeah, so that's a very, very important question, and I actually only realized, let's say, in 2016 I started to realize that we will expect a large, large change in emissions in the global south by listening to an inaugural address by one of the professors in the Netherlands. So she talked about the huge expected increase of population in Africa. And I was actually a bit shocked about what was said there. So we expect in 2050 about a doubling of the population of Africa, and 2100 more than tripling. So we go from the current 1.1 billion to 3.8 billion people in Africa. Of course, these predictions do not always come fully true, but even if you would have half of that, it's unprecedented. We never, never saw, in that short time frame of 70 years, a population increase like that. It will also mean, and there was actually a news article about that, and it was composed, I think it was last year or the year before, where they talked about mega cities. Where are the current mega cities? In 2050 most of them will be in Asia. Where are they in 2100? Then there is this huge shift of mega cities, and they will go to Africa, basically, and the 10 largest mega cities will be in Africa. So that is a change, which is unimaginable, but this is what is currently expected. Now, at the same time, there is a large industrial revolution going on in Africa, and that means that they will use our current technology to improve their industrial and economic power, and combined, that will lead to high increase of air pollutants and also greenhouse gasses. Of course, for the people in Africa, it's very important to know how much air pollution there is, and it's the same as in the US and Europe, not everyone is really aware of that. So measuring it is crucial to show how high the pollution levels are, and air pollution has a serious health impact. It's the fourth impact where we die on average on the globe, so it's much higher than people think. So we are very aware of pollution in food. You know, our supermarkets will be empty when something like that happens. Also water, we had a recent example where people had to buy water in the shops instead of getting it just from the systems in home, but air pollution we're not really aware of. And we can only live a couple of minutes without air. We can live days without water and months without food. But that is probably also the ticket, which turns it you know, we cannot. We do not have a lot of choice. We have to live there. So the awareness of that is really, really important. Well, when you look at the Global South, this is not only Africa, but also South America and Australia. When you look at that, we didn't plan any of what we call geostationary satellites over any of these continents. We have two types of satellites. So you have polar satellites, which OMI and TOPOMI are, for example. So you fly from pole to pole. You fly with the sun. These types of machines are dependent on the sun. So it means that you have one machine today in the end with a data global conference and for OMI and TOPOMI, that is around 1:30pm in the afternoon, everywhere, local time. When you have your geostation satellite, you are much higher in the, not the atmosphere, but outside the atmosphere, basically. But you look at a continent constantly. So these are what you see a lot in the evening for the weather satellites when you follow the clouds. Now you see these movies when you have the weather prediction. So these satellites, they follow the continent during the day, and that means that you can follow the change of air pollution during the day, and it does change during the day. You can think of rush hour, but there's also a lot of chemistry going on, which changes during the day depending on how much sunlight there is and this combination makes it a complex picture, but a picture we generally understand. So when you think about the Global South, these satellites, we did put them in the books, you know, it's not even in our thinking of the satellite community that we should have these types of satellites also over the Global South. So that's what I'm now advocating for. And it's even more needed because the count based measurements are so so so limited in a global surface. When you see the images of how many measurements you have in the northern hemisphere and how many in the southern hemisphere, it's an unbelievable difference. So when you would have in geosciences satellites, for example, in Africa, you would have, on top of the OMI and TROPOMI measurements, you would have suddenly eight to 10 measurements a day over a complete continent of several of these trace gasses, which play an important role in air pollution and greenhouse gasses. So the air pollution is important for the people in the continent, the greenhouse gasses, unfortunately, are important for everybody on the globe, because they determine, in the end, a large part of climate change. So if that source is suddenly going to increase hugely in, let's say, 30 to 50 years from now, that will not only impact Africa, but everyone. So this initiative, we have an international science based community where we discuss these new plans and ideas. So we go to write a concept paper about that. One of our really important focuses is that we want to have science teams where we have African scientists. So we are reaching out for that and trying to really have a combined science team. And one of the goals is also then to not only have what we call an account computer segment in the United States with all data, but also in Africa, because data empowers in the end. So these are the initial ideas. We still have to do a lot of work. We are not where we want to be, but this is the start of that.
Dan: Well, it's been really interesting to hear about what these instruments allow you to see in terms of air pollution, and what you're able to to know and infer about emissions. And you know this episode will drop around the time COP29 starts in Azerbaijan, but we're recording this during the Biodiversity COP, and I'm curious if you could talk a little bit about what your work has revealed about issues on the Earth's surface, like biodiversity and the nitrogen cycle.
Pieternel: So I co-led, together with a colleague from Belgium, a new idea to measure the nitrogen cycle. The satellite for that is called Nitrosat. So my colleague from Belgium is Pierre-Francois Coheur, and he's the lead, and I'm the co-lead of that initiative. We proposed it several times now for ESA Earth Explorer mission. So these are scientific missions, and we were evaluated three times, very, very well. But this is a hard competition. So you do not always come through. So the last selection, we didn't make. The next step, we had to face actually, which was already very, very good. So that was better than the first one. So we did work on this whole idea now for two years in far more detail than we were able to do before that. So we are now thinking about how to go further. So we will discuss it as well in Europe as in the United States. And why do we think that's so important? So the nitrogen cycle, when you look from an atmosphere composition point of view, you're basically talking about nitrogen dioxide, which we already talked about, and ammonia. And they consist, they determine, let's say, about 90% of the trace gasses involved in the whole cycle are in the atmosphere. So that's NO2 and ammonia. So therefore, we think we can really make an important contribution by measuring that with very, very high space resolution. That's our goal. So we want to go one by one, maybe even 500 by 500 meters, it will not be daily global coverage. But it's a science mission, it's really to find out, how does this whole cycle work? It's not so easy to measure ammonia with count based measurements. It can be done, but it's much more difficult to measure NO2, for example, so we could really contribute to that. It's important for many reasons. One is that NO2 and ammonia are combined to a well known aerosol, which is ammonia nitrate. We have a huge, high percentage of that in Europe, but also here in the United States. It's also important for water quality, because they both rain out, for example, and that pollutes our water, and we drink that water, and that also influences biodiversity. And biodiversity, of course, is extremely important. If you have too much nitrogen, then you basically limit your biodiversity. And biodiversity is like it, in the end, determines how well you are resistant to all kinds of illnesses as plants. And so it will be selective. If you have too much nitrogen, some plants will not be able to survive and in the long run, that will also influence the capability for agriculture.
Alison: So our primary audience here at EESI are policymakers. So I wanted to ask you a policy question. Climate change and air pollution are often handled separately in policy-making, even though these two issues are very closely intertwined from a scientific perspective, what is your team doing to help bridge this gap?
Pieternel: Yeah, this is a really good question, actually, yeah, when I gave my inaugural address at University of Delft in 2007 this was basically my main theme. So what you see is the policy makers for our air quality legislation are usually different ones than the ones for climate legislation, and then often even in different ministries. But if you look from a chemistry point of view, all these trace gasses are connected in the chemistry, because they react with each other. So if you have a policy for air pollution, it will impact climate change, and if you have a policy for climate it will impact air pollution. So it's really important to look at this from a combined view and yeah, we try to advocate for it. We had an OMI and TROPOMI meeting at my lab in NCAR in June. And I think TROPOMI, by its nature, measuring air pollution and greenhouse gas methane gets now the community from science based something together in one room, and realizing we really need to talk more to each other, because we have to understand the chemistry issues at full, and also if we would take measures, or if measures are taken, how would it impact the atmospheric composition? So I think the new instrumentation is coming to that more and more. So we will see new instrumentation, for example, for ESA, which is called CO2M. That mission is a comparative, very important mission. It will measure CO2 and methane, but it will also have a nitrogen dioxide channel. Why is that? That is because, if you think of CO2, you want to distinguish the CO2 caused by anthropogenic activities from natural CO2. A main indicator for that is nitrogen dioxide, because, as I said at the start when you burn fossil fuels, you will release CO2 and NO2. NO2 is very short lived, up to eight hours, so it's very close to the source. So when you measure NO2, you know what the source is, the anthropogenic source, and you will see that NO2 of the ocean is barely there, except for ships and lightning, because there is not a big anthropogenic source there, but over land, depending on where people live, there's a lot of NO2. So NO2 is a direct signal from an anthropogenic fossil fuel source, and when we use that measurement combined with the CO2, we are better capable of saying, okay, this CO2 is from an anthropogenic source, and that is the CO2, which is the forest or natural sources, so we will get more and more satellites. So not only CO2M, but also a new initiative from the Netherlands called danco, we'll do this combination, and also Japanese the following instrument for cosat will also have an NO2 channel, so we will get more and more emissions measurements combined, and that will also enable us to improve science, and we hope it will enter the policy space. But of course, the policy makers have to make their own decisions on that, but we would be able to share that knowledge.
Alison: So before we wrap up, I actually want to ask you a question about your journey. You were on a team of three scientists, all women who received the NASA-USGS Pecora Award in 2018 for the OMI satellite’s daily global coverage. What advice would you give to your younger self when you were a recent graduate pursuing a career in the male dominated world of STEM?
Pieternel: It might be good to tell you how that started. So when I became OMI Principal Investigator (PI), I did not have two female co-PIs. I had two male co-PIs, and they were both quite a lot older than I was. So that's how I started and that was also a bit overwhelming. I fully confess that. So what would be good advice? I think what is really important is to get good mentors, male and female. I was very, very lucky with my two co-PIs eyes. They were very good mentors. And so that is really important to have. And in that team of the whole satellite, there was one female scientist, and that was also an important mentor. So you have to catch your mentors. What is really important is that when you catch comments on whatever you do, please be selective on what you react to and what you let go. And these choices are crucial for your career, because you know when you really want to push an instrument, sometimes you have to be very strict, and that will not always be appreciated. But sometimes you have to do that, and then you should do it, but you don't always have to do that. Some things are less important, so try to cut that emotion out and really, really focus on what is needed for the science of your instrument. So that is some important advice. And for myself, I think what’s very important is also the work-life balance that will be different for everybody, but that is something you really have to take into account. So friends or family supporting you, because when you do these types of projects, it's a lot of money in the end, so there is stress. There's no way around that. You have to be able to deal with that, and then your social network is extremely important to it. And one last point is that sometimes women tend to be very modest. Try to express yourself, and you really think this is my idea, then claim it not everywhere, not every time, but also really, really important, you should do it and speak out. And then I got two female PIs and that's now for more than 10 years. So that's, that's also a very long period, but both PI teams have been really, really wonderful. It has been a very, very exceptional experience.
Dan: Well, Pieternel, now thank you for joining us. Thank you for visiting us in EESI World Headquarters. It was really, really fun to talk to you and learn about your work and OMI and TROPOMI. And I think it might be fun to find a job just naming satellites, because I feel like Nitrosat and MOPITT, I feel like I'd be good at that, but this was such a delight. Thank you so much for coming in today, and good luck with everything, and we'll be keeping an eye out tracking all the great stuff that you're advocating for and that you and your colleagues at NCAR are putting out. Thank you. Well, Alison, that was a ton of fun. Pieternel was a great guest, and it's just really fun to have a conversation in person. I can't believe it's taken us this long, but that was really cool. I just think it's so interesting that in some of these instances, the easiest, fastest and sometimes most cost effective solution is to launch a satellite. I just think conceptually, that's really cool. But I thought what Pieternel was saying about the ability to monitor CO2 and then monitor nitrogen dioxide, and then take how those two things are related and use them to make judgments about what's anthropogenic and what's naturally occurring. I think that's just really interesting, but that was really cool. I'm really glad we have scientists like her and her colleagues at NCAR doing this great work, because where would we be, without these high quality data measurements? And I think it's also just so inspiring, but also so important for someone in her position to take leadership and advocate for expanding measurement coverage in Africa and South America. You know, being ahead of those, those growth curves, is really, really important. And she obviously is concerned about it, and it's just great to see and to hear about her work advocating for those regions.
Alison: Yeah, I find it amazing to think about how these satellites will get full global coverage every single day. And yet, somehow, on a plane, it takes me 20 hours to get to Santiago. But I was thinking about something that I learned in one of our briefings about how the number one source of methane emissions in the United States is actually leaks. And so when she was talking about their monitoring of methane through the TROPOMI satellite, or the satellite instrument. It made me wonder if that's how we found out that statistic, or if it's not how we discovered it, it's certainly how we gather a lot more information about it. But I was also struck by what she was saying about the shifting population dynamics, especially the population growth in Africa. I think that there should be a lot more climate action plans that take into consideration these changing dynamics, because, you know, the major population centers right now might not necessarily stay that way in 20, 30, 40, years. I also really liked what she was saying about the nitrogen cycle and how she and her team is working to try to monitor that more closely. I think it really underscores the connection between climate change and biodiversity, which is often underestimated in a lot of climate talks. If you want to learn more about EESI's work on climate science, head to our website at eesi.org Also follow us on social media @eesionline for all of our recent updates. We're very excited, we just hit 6000 followers on LinkedIn. The Climate Conversation is published as a supplement to our biweekly newsletter, Climate Change Solutions. Go to eesi.org/signup to subscribe, and there you can also sign up for COP Dispatch, which will be our daily coverage of COP29. Thanks for joining us and see you next time.
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