Tracking Carbon Through Your Gut And Beyond In a recent survey, many college students said body fat is "burned off." Few knew that gymgoers actually break down fat molecules into carbon dioxide and water, extracting energy in the process. Ira Flatow and guests discuss the basics of energy, matter and the carbon cycle.
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Tracking Carbon Through Your Gut And Beyond

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Tracking Carbon Through Your Gut And Beyond

Tracking Carbon Through Your Gut And Beyond

Tracking Carbon Through Your Gut And Beyond

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

In a recent survey, many college students said body fat is "burned off." Few knew that gymgoers actually break down fat molecules into carbon dioxide and water, extracting energy in the process. Ira Flatow and guests discuss the basics of energy, matter and the carbon cycle.

Andy Anderson, professor, Department of Teacher Education, Michigan State University, East Lansing, Mich.

Ralph Keeling, program director, Scripps CO2 Program, professor and principle investigator, Atmospheric Oxygen Research Group, Scripps Institution of Oceanography, La Jolla, Calif.


You're listening to SCIENCE FRIDAY. I'm Ira Flatow. A little bit later, we'll be talking about social networking, and how many identities do you need?

But first we're going to talk about carbon. And we talk about carbon on this show all the time, right? Carbon emissions, carbon footprint, carbon cycle. But how much would you say that you really know about carbon, about the basic processes that transform carbon from one form to another?

Like when you burn fossil fuels and turn these hydrocarbons into carbon dioxide and water, how does that work? Or how does a cow turn grass into gas? Ever wondered about that? I'm sure you do, certainly if you live on a farm.

And how about this one: If you go to the gym to burn off fat, what exactly does that mean when you say you're going to burn it off. Burning, what is actually happening to those fat, carbon-filled molecules? Where do they go? Carbon, and how it gets recycled about nature, it's all very fascinating, and that's what we're going to be talking about.

And here to walk us through some of the basics is Andy Anderson. He's professor in the Department of Teacher Education at Michigan State University in East Lansing.

And he works with a group of science teachers who have been studying how college students think about the carbon cycle, and what he has discovered is very interesting. They published their work in the journal Bioscience. Welcome to SCIENCE FRIDAY, Dr. Anderson.

Dr. ANDY ANDERSON (Michigan State University): Thank you, good to be on.

FLATOW: You can't escape carbon, can you?

Dr. ANDERSON: Not if you want to stay alive.

(Soundbite of laughter)

FLATOW: Thank you very much. Why did you do this study about how much we know, because it is that important, carbon?

Dr. ANDERSON: Absolutely. You know, not only is it fundamental to life, but also there's a sort of fixed amount of carbon in the environment, and where that carbon ends up is critical in terms of what happens in terms of climate change.

FLATOW: Uh-huh. Let's talk about some of the things that go on in the carbon cycle. Let me go back to the gym analogy I had there. When you talk about burning fat, I'm going to burn fat, are we really burning fat off? What's happening?

Dr. ANDERSON: Well, you know, in a way, burning is not a bad analogy for what's happening to your fat. But what we found out is that for most college students, burning means the equivalent of disappearing, when you ask them.

Okay, so the fat's got a bunch of carbon and hydrogen and oxygen atoms in it. What's happening to those carbon and hydrogen and oxygen atoms? What they tend to say is that they are burned up or burned off or something like that, or they'll say that they're converted into energy.

And both of those are absolutely wrong, that in fact when you lose weight what you're doing is you're breathing it out. The fat's being converted to carbon dioxide and water, and so it's leaving your body mostly with your breath.

FLATOW: Oh, so it's not burning, it's breathing.

Dr. ANDERSON: Or breathing is the way you get rid of the products of cellular respiration, which is a lot like burning.

FLATOW: So what about when we eat food? Are we actually getting energy from the food? Is the carbon going into our bodies, and what's happening there?

Dr. ANDERSON: Yes, you're getting energy from the food but not from the carbon atoms themselves. When you say the carbon atoms are not being transformed into energy that you use, instead it's more like the bonds in the food.

Food has a lot of carbon-carbon and carbon-hydrogen bonds, which are relatively high in energy. And when you oxidize it and end up with carbon-oxygen and hydrogen-oxygen bonds, those are lower in energy, and the energy that's released is the energy that you use for body functions. It's also the energy that keeps your body warm.

FLATOW: So it's not the energy directly from the food that we're eating that we're using to make - it's not the product of the food itself, directly, that we're making energy from? It's from breaking the bonds, sort of.

Dr. ANDERSON: That's right. It's the bonds and not the atoms in the food that are the source of the energy.

FLATOW: Interesting, and what about trees? You know, you can't talk about carbon and carbon footprints and burning fossil fuels and wood and all these kind of things without talking about the carbon in trees. Does it - I think we all think that a tree grows, you plant a tree in the ground, you water it, you fertilize it, fertilizer goes up the roots and creates a big oak tree. Is that how it works?

Dr. ANDERSON: Well, not exactly.

(Soundbite of laughter)

Dr. ANDERSON: It's like - most of our college students know that trees sort of breathe the opposite of us, that we breathe in oxygen, breathe out carbon dioxide, and trees breathe in carbon dioxide and breathe out oxygen.

But they don't connect that knowledge with their ideas about the way the tree grows. So they still often think of trees as getting most of their mass from the soil, but it's not the soil that's the source of most of the mass of the tree. It's actually the carbon dioxide.

So 90 percent of the mass of the tree comes from the carbon dioxide in the air, and the remainder comes from water and soil and minerals.

FLATOW: Ninety percent comes from the CO2 in the air?

Dr. ANDERSON: At least, yes.

FLATOW: Just by sort of inhaling the CO2, going through photosynthesis and making that mass?

Dr. ANDERSON: Absolutely, yes. And of course, trees don't inhale. They have little holes in the bottom of their leaves called stomata, and the air filters in through those, and they use the carbon dioxide from the air, and then they - what filters back out is air that's richer in oxygen and poorer in carbon dioxide.

FLATOW: Quite interesting, 1-800-989-8255 is our number, if you want to talk about carbon and carbon dioxide. And this interesting test that you gave the students: There was a question on your test about a moldy piece of bread. Interesting, want to tell us about that? What were you trying to find out in that question?

Dr. ANDERSON: Yeah, again, when we're - when we think about decay, people tend to think of decay like a rotting fruit or a moldy piece of bread or a tree decaying, they tend to think of that as a process of going back into the soil.

You know, it's even incorporated into common sayings like ashes to ashes and dust to dust. But that's not really - it would be better to say carbon dioxide to carbon dioxide, because when the bread or the tree decays, the primary products again are carbon dioxide and water, and there's just a little bit of mineral substances, nitrogen, phosphorous and so forth, that are going to remain and possibly go back into the soil.

FLATOW: I think hardly anybody realizes that, you know? And is that something you have to unteach people when you teach students about the right way that it happens?

Dr. ANDERSON: Yes. They - you know, students come in with these perfectly sensible ways of thinking about how the world works. And those ways work just fine in most circumstances. Like if you're interested in losing weight, it doesn't really matter whether the fat is just disappearing or whether it's being converted to carbon dioxide and water and you're breathing it out.

And so students memorize a lot of stuff, and they learn how to recite chemical formulas and things like that, but it doesn't change the way they think about these basic, everyday processes.

FLATOW: Let's go to the phones. Janica(ph) in Washington. Hi, welcome to SCIENCE FRIDAY.

JANICA (Caller): Hi, yeah. This is a little bit early for this suggestion. I was thinking it would fit in better later, but here goes. I've had this idea for a long time, after reading Herman Daly. Is your guest familiar with the economist Herman Daly?

Dr. ANDERSON: No, I'm afraid I'm not.

JANICA: Okay, he wrote "Beyond Growth." Anyway, he writes as if ecology and economy are one and the same, and I'm sure you've thought about it and realize that that's kind of the case.

But my idea is a required course for kids to learn how to evaluate the environmental economic cost of everything they use, from the very beginning, you know, the extraction of the resources, to its very end as garbage and what happens to it at that point, and to be able to evaluate the total effect on the environment.

FLATOW: Let me get a reaction because I'm running out of time. Good idea? At least certainly where carbon is concerned, right?

Dr. ANDERSON: Yes, we talk about that as life cycle analysis, and an important part of life cycle analysis is the carbon footprint, and the idea underlying the carbon footprint is that we have, you know, we've got carbon in various places, and if it's in organic matter, like in food or fuel or things like that, then it's pretty - it's harmless to the environment. But when you release it into the environment as carbon (technical difficulties) then it becomes a contributor to global warming.

FLATOW: And it's the carbon that's getting recycled over and over again. It's being taken up and then put back in nature.

Dr. ANDERSON: It's getting recycled over and over again, except now we've thrown that cycling out of balance by burning a lot of fossil fuels, and therefore we're putting a lot more carbon into the atmosphere than we're taking back out.

FLATOW: Speaking of CO2, I want to bring on another guest who says now they are being able to set up a system where they can actually track a cloud of CO2 across the world to see where it's coming from.

Ralph Keeling is director of the Scripps Oxygen and CO2 Programs at the Scripps Institution of Oceanography. That's University of California, San Diego. He joins us by phone. Welcome to SCIENCE FRIDAY.

Mr. RALPH KEELING (Scripps Institution of Oceanography): Thank you, it's good to be on.

FLATOW: Tell us about the program. You're actually setting up a monitoring system?

Mr. KEELING: Yeah, in the last week there was - and on Wednesday in particular there was an announcement of an expanded network to measure greenhouse gases, particularly carbon dioxide and methane, at 50 stations in the U.S. and a comparable number internationally with the goal of quantifying greenhouse gas emissions.

FLATOW: Mm-hmm. And what part of the world can you monitor?

Mr. KEELING: Well, let me - let's - a little history here. The systematic tracking of greenhouse gases started already back in the 1950s with my father's contributions at Mauna Loa in the South Pole, and there's been expanded efforts since then. It's been incremental. Major players include various government agencies like NOAA. And through these observations, you can increasingly make inferences about where the carbon dioxide is coming from and going to, getting beyond just the question of whether it's building up in the atmosphere.

FLATOW: Mm-hmm.

Mr. KEELING: But our ability to date is really rather coarse. We can make statements about whole continents or large ocean basins. But to try to make statements about emissions on politically relevant footprints like counties or countries has not really been feasible yet. And this network is targeting the expansion to allow that to happen.

FLATOW: So you'll be able to trace the origins of a large cloud of CO2.

Mr. KEELING: Exactly.

FLATOW: (Unintelligible) cloud where it came from.

Mr. KEELING: Yeah. Just like a smokestack has a plume that - and if you're sitting downwind, you can tell that there's CO2 coming and, with accurate measurements, even quantify more or less what it's coming from. And you can do the same thing with a city. You can do the same thing with a country if you have enough measurements in the right sorts of places and take account of the winds.

FLATOW: And where would those places be that you'd like to set up the measurements?

Mr. KEELING: Well, there is a core background network of observations now at clean sites like Mauna Loa and throughout the world maintained by NOAA and other programs like ours here. And that gives us a pretty good handle already on the clean air parts of the atmosphere. There's also expansion that's gone on over the U.S. and over Europe in particular, to try to measure carbon dioxide concentrations and methane and other greenhouse gases. There's columns - that is, throughout the vertical atmospheric column, over continental regions. And what this network would do will rapidly expand the level of those efforts, so that we can really start to make some firm estimates of numbers.

FLATOW: So we could see where the big greenhouse gas emitters are coming from.

Mr. KEELING: Yeah. I mean at this point, the way we tabulate greenhouse gas emissions, countries are obliged to - the countries under the Framework Convention are obliged to report their emissions of greenhouse gases. And the approaches for doing that involve keeping track of the processes that emit carbon dioxide like various industrial processes or raw material flows and so forth. This is a so-called bottom-up accounting.

And one of the questions that one faces is the question of whether what you actually compute with that is accurate relative to what you emit. It's a little bit like going on a diet and assuming you know what you're doing simply by counting calories. You very much like to know that you're actually losing weight. And what you need to do is have some kind of measurement that actually tracks the actual mass flow, and that's what we can do with the atmosphere.

FLATOW: Talking about carbon dioxide this hour on SCIENCE FRIDAY from NPR.

And once you know that, then that goes into the political arena.

Mr. KEELING: Well, yeah. I think the main interested parties will be governments and other entities that are concerned about their emissions. The assumption here is that the value of this kind of information will increase with time as people get more and more serious about cutting their emissions.

Another important application for this information is really in education. Greenhouse gases, you can't see them. You can't smell them, but they're all around you. And we will have a, through this program, an ability to track in details levels of carbon dioxide in a level that's never been done before. Methane, I should say, as well. So there will be visualization capabilities that will help people understand what's going on around them on a daily basis.

FLATOW: Mm-hmm. And how soon will the network be finalized?

Mr. KEELING: Well, you know, this is a private company that my colleague, Ray Weiss and I here at the Scripps Institution of Oceanography at UC San Diego, were teamed up with. The tapes will be set by their ability to roll out. They're confident they can do this quite quickly. We're engaged in helping make sure that the data are high quality, so we're putting the brakes on a little bit to make sure we don't skip any important steps. But it's going ahead pretty quickly at the moment. But it'll be months or a year or so before we have something at the scale we're talking about.

FLATOW: I can see Wall Street already creating CO2 futures or derivatives or some sort of thing...

(Soundbite of laughter)

FLATOW: ...that will be based on this. Any reaction to that, Andy?

Prof. ANDERSON: I think one of - it provides an interesting educational opportunity, because what we see is that a lot of people, especially when we do research with younger kids, they're not really quite sure what carbon dioxide is.

FLATOW: Mm-hmm.

Prof. ANDERSON: They often think of it as more like a quality of the air than a component of the air. So carbon dioxide is good air and oxygen is bad air. And I think having these kinds of quantitative data and talking about carbon dioxide's origins and so forth, there's a real opportunity for students to learn about carbon dioxide and its sources.

FLATOW: Do they realize the interaction between CO2 and the oceans?

Prof. ANDERSON: Oh, no.

FLATOW: Oh, no.

(Soundbite of laughter)

FLATOW: But it's an important one, is it not?

Prof. ANDERSON: Oh, it is important, although, you know, carbon dioxide dissolving in the oceans is not a primary driver of climate change. It moderates the pace of climate change. But you know, what's driving it has much more to do with what we're doing on land.

FLATOW: Mm-hmm. And you'll be able to, Ralph, track these CO2 clouds even if they cross oceans?

Mr. KEELING: Yeah. I mean, I would say that the existing network of -you know, the backbone that's sustained by NOAA and these other agencies, is already giving us a pretty good handle on the flows of carbon on these very large scales, like over ocean basins. And so the frontier that needs to be pursued to advance the capability is really more over land than over the oceans. We do, however, depend very much on our oceanographic colleagues to keep track of what's going on in the water. So, again, that's actually part of the backbone that we build upon as the oceanographic communities contributions to carbon measurements.

FLATOW: Well, good luck to both of you, gentlemen. And thank you both for taking time to be with us today.

Prof. ANDERSON: Thank you.

Mr. KEELING: Thank you.

FLATOW: You're welcome. Andy Anderson is a professor in the Department of Teacher Education at Michigan State University in East Lansing. Ralph Keeling is director of the Scripps Oxygen and CO2 programs at the Scripps Institute of Oceanography. That's at the University of California in San Diego.

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