Dr. Prasad Kasibhatla is a faculty member in the Nicholas School of the Environment, and the Pratt School of Engineering at Duke University. And his expertise lies in atmospheric chemistry, how humans have changed it over time, what that means for climate change, and in turn, what that means for us.
In this episode, we get down to the basics. How does climate change even work? Why should we care? Can carbon neutrality fix climate change? And what can we do to help?
CREDITS:
Guest: Dr. Prasad Kasibhatla
Hosts: Katherine Li, Emily Nagamoto
Producers: Katherine Li, Emily Nagamoto, Olivia Fox, Matthew Brune
Music:
Cali by Wataboi
What u thinking by Wataboi
TRANSCRIPT:
STUDENTS:
He's like, Yeah, I don't think science knows.
Oh no. Science here. I know.
KATHERINE:
Hey, welcome to Operation Climate, a podcast made by young people, for young people, where we break down environmental issues through conversations with cool people.
KATHERINE: Hello, everyone, my name is Katherine.
EMILY: And I'm Emily.
KATHERINE: And we are your hosts for today's episode of Operation Climate. What are we talking about today, Emily?
EMILY: We are going to talk about the science behind climate change.
KATHERINE: Ooh, very interesting. I know, when I was first learning about climate change, it took me a really long time to like actually wrap my head around, like, what these greenhouse gases are and what they're actually doing in our atmosphere and how this all works. Did you ever feel that way Emily?
EMILY: Oh, for sure. I feel like, especially now, you know, when people are becoming more aware about climate change, and maybe going out on the streets and protesting, a lot of people might not actually know, you know, why is our atmosphere getting hotter? And is this human cause? How is it human caused? So I think it'd be really good to investigate these questions. KATHERINE: Yeah, exactly. So listeners, in this episode, you're gonna learn about greenhouse gases, what they actually are, what they're doing in our atmosphere, and ways that we can mitigate the effects of climate change.
KATHERINE:
First, why should we even care about the science behind climate change? Here's what some Duke students have to say.
STUDENTS: This is relevant to every single person on this planet. It's important and it's affecting us every day and will continue to affect us If we're not making a constant change. You know, it's not, it's not something that you cannot teach people. Because it's just a part of what the world is going to be like. Yeah, it's really hard to fix a problem if you don't understand it.
KATHERINE: So climate change is a pretty big issue. And that's an understatement. But what can we actually do about it?
EMILY: So there's this concept called carbon neutrality. And I feel like I've been hearing a lot about it in the news and from corporations that are saying, you know, we're going carbon neutral. But I'd be excited to hear more about what that actually means. So are we going to answer that question today, Katherine?
KATHERINE: We are, and to answer that question, we are joined by a super awesome guest for today's episode. His name is Dr. Prasad Kasibhatla. He's a faculty in the Nicholas School of the Environment, and the Pratt School of Engineering at Duke University. And his expertise lies in atmospheric chemistry, how humans have changed it over time, what that means for climate change, and in turn, what that means for us.
EMILY: I'm excited. Let's get started.
EMILY: So first, Professor, can you tell us a little bit about yourself? Like, what's your area of expertise? And what's your current research focused on?
KASIBHATLA: Sure. So I'm in the faculty of the Nicholas School of the Environment at Duke University. And my research kind of broadly focuses on human impacts on atmospheric chemistry, atmospheric chemical composition, and the consequences of that.
KATHERINE: To give you some context, for the rest of this interview, the greenhouse gases that we're going to be talking about include carbon dioxide, methane, nitrous oxide, fluorinated gases and water vapor. Fluorinated gases are a really interesting greenhouse gas because they're actually entirely manmade and do not occur in the natural environment. However, in the rest of this episode, we're going to be focusing on carbon dioxide. And you'll find out later why we choose to focus on this one.
KATHERINE: I think it'd be nice for our listeners to just get a very basic introduction to what these greenhouse gases are actually doing in our atmosphere.
KASIBHATLA: So what happens is the way the earth maintains its temperature is that we get energy from the sun, that energy is coming in, essentially, the visible wavelengths. And part of that energy is reflected back to space; it’s reflected by clouds, it’s reflected by snow covered surfaces, things like that. To a rough approximation, something like 30% of the energy coming in from the Sun is reflected back and the other 70% gets down to the surface. To a rough approximation, you can assume that the surface absorbs that 70% and then releases that energy back to space in the form of infrared energy.
So we're getting it in the visible, emitting it as infrared. There are certain gases that are absorbed in that infrared region. And when those gases absorb the infrared, you can think of it as really trapping that and preventing it from going to space. That's really not what's going on. But you can think of it that way. Essentially, what you're doing is you're reducing the efficiency at which you emit that energy back to space. To get back in balance, the earth has to heat up; as it heats up, it then releases more of that energy back to space. And so that's really what causes that warming. It's when you absorb that infrared energy, to release that back, the atmosphere has to warm up to release that energy back to space.
KATHERINE: So Professor Kasibhatla provided a very sciency explanation of how the earth warms when we put greenhouse gases into the atmosphere. But if you're still having trouble understanding exactly how this works, think about it this way. Okay, so picture this, you're in a really cold room so you're going to put on a blanket. When you have this blanket on, heat energy is going to leave your body and it's going to be absorbed by your blanket. And this heat energy is going to travel through the fibers of your blanket until it reaches your room, and then it's going to be lost to your room. And this is going to go on and on. And eventually, you're going to reach a balance where the amount of heat that is being lost to your room is equal to the amount of heat that your body is producing. And your skin's gonna remain at a constant temperature.
So what if you put on another blanket? If you put on another blanket, that means the heat that your body is producing has to travel through more fibers before it can finally be released into your room. This is going to upset the original energy balance that we had. The amount of energy being released to your room is not the same as the amount of energy that you're giving off. You're gonna get warmer and warmer until that energy balance is satisfied, and your skin remains at a constant temperature. And this is what is happening to the Earth's surface when we add more greenhouse gases to the atmosphere.
KASIBHATLA: And so you know, that has led to a warming of about one degree Celsius, but there's still some warming in the pipeline. And what I mean by that is our system hasn't yet responded to these past emissions of greenhouse gases. So if we could hold our composition the same as today, magically, right, there'll still be some warming to take place before we get back out. And we call that committed warming. So there's still some warming in the pipeline we're already committed to.
KATHERINE: Next, we wanted to get Dr. Kasibhatla’s answer to something that I think is a talking point for a lot of climate deniers when they're arguing against the need for climate action. Could you explain the difference between natural and human caused climate change?
KASIBHATLA: Well, a couple of things, right? One, climate system of the Earth is extremely complex, okay. It involves interaction with energy coming in from the sun and nonlinear complex interaction between the oceans and the atmosphere and the land and the atmosphere. There are these complex interactions that take place. Climate naturally varies, okay. But what we are seeing clearly superimposed on what we call natural variability, is this trend is clearly driven by changes because of human activity. So yes, there's always natural climate variability. But we're seeing changes that are about beyond that natural variability. And the importance in my mind is that, you know, human systems, ecological systems, have kind of evolved with this natural variability in mind. And we're now driving that system outside those bounds of natural variability.
KATHERINE: So this is the point that you can take to climate deniers. You can say, yes, climate change is a natural thing that happens, but not to the extent that we are seeing today. The climate change that we're seeing today is way beyond what is considered natural.
Now let's get into how we can actually fix this problem.
KATHERINE: Could you explain what exactly people mean, when they say that something is carbon neutral? What exactly is carbon neutrality?
KASIBHATLA: The amount of CO2 in the atmosphere has risen pretty significantly in the last 250 years or so ever since the advent of industrialization, partly because of fossil fuel combustion, and partly because of land clearing of deforestation in the tropics. We think currently, about 90% of human emissions are because of fossil fuel combustion, the other 10% because of deforestation. Now, this has driven CO2 levels up in the atmosphere. In the atmosphere, CO2 levels fluctuated between 180 parts per million and 280 parts per million between two interglacial periods. Because of the consequences of human actions, CO2 has now risen to about 415 parts per million today. And it's still rising at about 2.5 parts per million a year. We are pretty confident that this rise in CO2 along with human induced rise in other greenhouse gases, like methane, and CFCs, and things like that, have led to a warming of global average temperature increase of about 1.1 degrees Celsius. There's a goal that the nations of the world have agreed to try to keep temperature rise relative to pre industrial to not more than two degrees Celsius, with an aspirational goal of 1.5 degrees Celsius. To get to that goal, you have to essentially eliminate all carbon emissions by the end of the century, and probably most of the emissions by the middle of the century. That's the context in which we talk about carbon neutrality, being that you've tried to get to zero emissions, or the amount you're putting in essentially, is the same as that which was losing every year.
KATHERINE: And you sort of touched on this in your answer. But what makes carbon special? I mean, from my understanding, there are other greenhouse gases that are a lot more potent than carbon dioxide. So why isn't there talk about becoming methane neutral or nitrous oxide neutral?
KASIBHATLA: So those are great questions. There's a lot of work being done on methane, and nitrous oxide and things like that. Methane, actually, is probably one of the critical things we have to focus on. Part of the reason is, if we act on methane, we can get benefits pretty quickly in the timescale of a decade or so, in terms of curtailing its rise in the atmosphere. CO2 is important because one, it is the dominant component in terms of what we call radiative forcing, how it’s changing the energy balance of the atmosphere. And that's because it is by far the most abundant greenhouse gas. And so that's the reason CO2 is important. Yes, we have to tackle methane. Yes, we have tackled nitrous oxide and other things like that; people are working on that. But at some point, we have to tackle CO2.
KATHERINE: So one important thing to note is that different greenhouse gases stay in the atmosphere for different amounts of time. For methane, it stays in the atmosphere for about a decade after it's emitted. For nitrous oxide, it stays for a little more than a century. But for carbon dioxide, once it's emitted into the atmosphere, 40% of it still remains after 100 years, 20% after 1000 years, and 10% as long as 10,000 years later.
KATHERINE: The different time periods that those different chemicals can stay in the atmosphere, does that play a factor as well into what we're focusing on?
KASIBHATLA: Well, in some sense, yes. Because CO2 essentially, that you put into the atmosphere, some portion of it stays in the atmosphere forever, you know, for centuries. Our hope is to not let the increase be too high. So if today's 415, maybe not let it get about 450 parts per million or so? While, for things like methane, you'd have to drive the concentrations down because they're short-term. For methane, essentially, if you cut emissions, then essentially, the methane concentrations will stabilize to whatever the steady state is that is in balance with natural sources.
EMILY: So in addition to talk of carbon neutrality, some people talk about going carbon negative. So what does that mean? What are your thoughts on that? Is it effective?
KASIBHATLA: Well, it can be but right now, we don't have the technology at scale to do that, right. So the idea is that you kind of grow fuel, maybe wood or something. And if you use that to be combusted, capture the carbon, and bury that carbon, it's essentially a negative source. But when you start getting into things like that, you really have to worry about competition of land for food versus for fuel. So there are multiple trade offs.
EMILY: So Professor Kasibhatla is touching on a subject called geoengineering. And you can listen to the first season of Operation Climate to learn more about that. It's where you deliberately modify the climate system in order to try to mitigate climate change. Capturing and storing carbon dioxide is one method that many are looking at as a way to slow down climate change, but no one has been able to do it yet at large scale.
KASIBHATLA: To me, I think that one of the things we really have to focus on is moving away from fossil fuel. I think that has to be our number one priority.
KATHERINE: One thing that Professor Kasibhatla mentions is that the main activities that we have to focus on when we're talking about reducing carbon emissions have to do with fossil fuels and agriculture. So fossil fuels were actually the source of 75% of human caused emissions in 2018. And that's because we use fossil fuels in so many of the daily activities that we do, because we need energy for so many of the daily activities that we do. Buildings that you live in, transportation, the phone or computer that you're listening to this podcast on right now. And with the products that you buy, these companies and factories use tons of energy to create the products that you use every day. We use energy for everything.
EMILY: A lot of people don't think of agriculture as being a big source of greenhouse gases. But actually, agriculture results in a ton of greenhouse gas emissions; some 80% of global deforestation is the result of agriculture production. And there are so many different ways that the agricultural industry uses fossil fuels as well. So from transporting goods, to the farm machinery, and, of course, as many of us have heard, cows and other livestock are a huge producer of methane as well.
EMILY: And we just kind of want to bring it home with a final question of: from an atmospheric chemistry point of view, what do you think people need to know about how we impact the atmosphere? And what can we do to limit negative effects? So both on an individual level and as a society.
KASIBHATLA: We, you know, we have changed the composition of the atmosphere significantly. In fact, Paul Krutzen, won a Nobel Prize for his work in atmospheric chemistry. He popularized this phrase called the Anthropocene to say that we're now in this era, where human impacts are rivaling the great geologic forces. So we are clearly, in a number of areas, you know, whether it's climate, whether it is air pollutants, significantly changed the composition of the atmosphere. A lot of it is because of a couple of things. Fossil fuel combustion and industrial agriculture. Those have kind of been the two drivers, we clearly have to address that.
I mean, at an individual level, you know, you can do a lot of things like try to conserve energy, and be as green as possible. But I would argue that at the individual level, the biggest thing you can do is make it a priority in terms of when you have to make decisions about who you elect and things like that. I would argue that's probably the biggest impact that people can make. At a national level, you know, the US has actually done very well with fighting air pollution, we've not had that same commitment to CO2 emissions. Climate and CO2 is a much trickier problem. Air pollution, for example, if the state of North Carolina cleans up its emissions, which impacts air pollution, we will accrue much of the benefits. The US cleans up its emissions, we'd accrue much of the benefits for things like CO2 and stuff. Everybody's emissions contribute to everybody else. So you're impacting everybody, everybody's impacting you, you could easily get into the situation where you say, you know, I'm not going to do anything, because what I do is insignificant. But if everybody argues that thing, nobody's going to do anything. So I think understanding that there's a common good, and acting for that common good is extremely important.
KATHERINE: So that concludes our very first episode of Season Four of Operation Climate.
Thank you so much for listening. We hope that you are informed now. And you have the basic toolkit for taking more action in the fight against the climate crisis.
EMILY: And also, with this knowledge of how climate change actually works, you should be better equipped to deal with anyone who comes to tell you that climate change doesn't exist, because it does, and it's real.
KATHERINE: Exactly. And you heard that from a real scientist. And also, us, me and Emily, who are studying scientific things so you can trust us. If you have any questions about the science behind climate change, links to more resources will be in our show notes.
Thanks so much for tuning into this episode of Operation Climate. Make sure to subscribe on Spotify, Apple podcasts, Google podcasts, and anywhere else that you find your podcasts. In order to stay updated about future episodes, visit our website at bit.ly/operationclimatepodcast for a full transcript of this episode, and for more information and links that you can explore to learn more about this topic that we covered today.
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