Ermias Kebreab: What do seaweed and cow burps have to do with climate change? Each year, one cow can belch 220 pounds of the greenhouse gas methane. Animal scientist Ermias Kebreab experimented with alternative cow diets and found a surprising solution: seaweed.

What do seaweed and cow burps have to do with climate change?

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So on this episode, we've talked about reimagining what we make things with. We've heard about why we should repair our products and how we could repurpose oil drilling technology to tap into geothermal power. But what about what we eat? Can we remake what goes on our plates?


ERMIAS KEBREAB: Yeah. So I've been working with cows for about 20 years or so.

ZOMORODI: This is biologist Ermias Kebreab. Growing up in Eritrea, Ermias saw how important milk and meat were to the nutrition of his family and his community.

KEBREAB: The majority of people in the world live in low-income countries where the main source of nutrition, the good nutrition, is an animal source food. I wanted to have ample opportunity for people to drink milk and to eat meat and, you know, basically lead a healthy life. That's what I wanted to do and that's what I studied - biology and agriculture. I've had a relationship with cows for quite a long time.


ZOMORODI: Now, Ermias is a professor at UC Davis, where he studies cows, specifically a problem with cows - their burps.


ZOMORODI: Those burps are full of methane, one of the greenhouse gases that contributes to climate change. In fact, cows account for 4% of U.S. greenhouse gas emissions every year.

I always thought that cows were particularly flatulent. Is this true?

KEBREAB: It is not.


KEBREAB: So most of the gas is formed in their stomach, so in their guts, particularly in the first chamber. And so they belch it out. By some estimates, between 95% to 97% of the methane comes from the front end of the cow. So the back end of the cow is really maybe 3% or less.


ZOMORODI: So for the past several years, Ermias and his team have been experimenting with how changing a cow's diet could safely and quickly lower the amount of methane in its belches. Here's Ermias Kebreab on the TED stage.


KEBREAB: So how can you reduce these methane burps? My colleagues and I may have found a solution - seaweed. Let me explain. A couple of years ago, an article was published that showed almost complete elimination of methane when seaweed was added to chopped grass in the lab. Great. But, as an agricultural researcher, I know lots of additives work well in the lab but not in real animals. But there was something different about seaweed and the way in which it reduced methane.

Some seaweeds contain ingredients that directly inhibit microbes in the cow's gut from forming methane without interfering with food digestion. So we thought we should test this in live animals. This was the first ever experiment in dairy cattle, and we had no idea how much to give them.


ZOMORODI: OK. So your team starts mixing in just a little bit of seaweed into the cow's regular feed. And what did the cows think? Like, did they like it?

KEBREAB: Well, the ones that we gave too much, they did not eat as much as we would like them to do it...

ZOMORODI: (Laughter) OK.

KEBREAB: Because, you know, just like the - cows are very picky eaters.

ZOMORODI: Oh, I didn't know that.

KEBREAB: Oh, yeah. They sort their feed. They will find the bits and pieces that they like.

ZOMORODI: (Laughter) It's like my dog.

KEBREAB: (Laughter) Yeah.

ZOMORODI: All right.

KEBREAB: So they didn't get used to it right away. But - so we gave them for about three weeks, and then we switched them around and then another three weeks and then we switched them around. And that was it.

ZOMORODI: And all the while, though, you're collecting their burps? That's not a sentence I thought I would ever say, Ermias.

KEBREAB: (Laughter).

ZOMORODI: How do you do that?

KEBREAB: The way we do it is, we have a device called GreenFeed.


KEBREAB: And what it does is it will entice them to come to this machine where they feed - they stick their head into this machine, and they feed from that machine. So as soon as they come in, the GreenFeed machine will drop some...


KEBREAB: ...What we call cow cookie. So they just eat this cow cookie. As they're eating, they will be breathing into this machine, and the machine will take out their breath. And then, right away, analyze in their burping how much methane, how much carbon dioxide, how much hydrogen there is and then automatically sends that information wirelessly. And the cows love it. I mean, you would see them line up to try to get into this machine.

ZOMORODI: (Laughter) OK, great. So you have very willing participants in your study. And what was your hypothesis? What did you sort of hope you would see?

KEBREAB: What I was hoping was that we see 10%, 20%, 30% at most reduction in emissions. That would make me very, very happy. But then, when we start doing this, and I start getting this report from my graduate student that the reduction was quite high, I couldn't believe it.


KEBREAB: In that first experiment, the emissions were reduced by up to 67%.


KEBREAB: And I thought, at first, the equipment must have malfunctioned. But it was real. But we are left with more questions than answers. Would the microbes in the gut get used to it and start producing methane over time? Would the seaweed be stable over a long period of time in storage? Would the taste be affected and the cows turn up their noses? Or would the seaweed affect the cows' health or milk production?

So we teamed up again to conduct another trial. Over a five-month period, we saw the seaweed reduce emissions by over 80%.


KEBREAB: Our colleagues in Australia, they saw up to 98% reduction in a similar trial. That kind of reduction is simply staggering. We have also seen an improvement in bulking up of the beef cattle with no adverse health effects. So it's a win for the environment. It's a win for the farmers and consumers. A panel of 112 people got to taste steak made from steers offered seaweed and control, and they did not detect any difference.


KEBREAB: We also did a nutritional quality of the meat, and we found no difference between animals that were offered seaweed and the control.

ZOMORODI: OK. So you do your first study with cows. It's highly successful. You do another study, it's even more successful, 80% methane reduction. Plus it doesn't seem to affect the cows' health. It makes them fat, healthy and still delicious. What does that make you want to do? Sort of - I assume this is the researchers' dream - right? - to prove that something works. But how do you go from having the solution to actually implementing the solution? What do you do with this knowledge?

KEBREAB: Yeah, that's a very good question. So not too long ago, the California Department of Food and Agriculture has given their approval that it be generally recognized as safe. So a certain formulation can now be sold in California as well. So it's moving in the right direction. The ultimate dream is then to get it into farmer's hands and be able to use it as soon as possible. And what I'm thinking is that, you know, maybe there's a premium product with a low-emission milk or meat as well. So...

ZOMORODI: So maybe I would go to the grocery store and I'd say, you know what? I'll pay the extra $0.25 to get...


ZOMORODI: ...The reduced-methane milk.

KEBREAB: Absolutely, yes. We've done that with energy. I mean, a number of states, they have this initiative where you pay a little bit more and you get a renewable source of energy instead of from fossil fuel. The same thing could apply here as well.

ZOMORODI: You know, I have to ask, I'm sure there are people listening - maybe they're vegetarian or, like me, who are trying to eat less meat and maybe thinking like, well, there's a very easy solution to this problem with cows and methane, just don't eat them, don't drink milk, just don't have as many cows, period. What do you think of that response?

KEBREAB: Yeah, so I think, in a lot of high-income countries, you may be able to get the nutrients and the micronutrients that people need to lead a healthy life. But most people don't live in high-income countries. And the other issue is that, you know, there is this issue of hidden hunger.

ZOMORODI: Wait, what is that? What is hidden hunger?

KEBREAB: You have enough calories and maybe even protein, but you don't have the trace minerals that your body needs to have a properly functioning system. So particularly for children, children below 5 years of age, what you see is the stunting levels are very much correlated with the animal source food consumption. In countries that have high consumption of animal source food, the stunting levels are much, much lower. In countries that do not - for example, in Sudan and India and others - the stunting levels of children under 5 years of age is over 40%. So the solution is to have those animals source foods in a way that is enough to be able to lead a normal life. So I think what we can do in the West or in high-income countries is consume animal source food according to our requirement. If you are overconsuming, then yes, you have to reduce the intake.

ZOMORODI: OK, so reduce the intake. If we - meaning, like, if we live somewhere where nutritious food is easy to get, we still need to cut back on eating meat. But you're also saying that we need to accept the reality that we need to feed everyone in the world.

KEBREAB: That's absolutely right, yes.

ZOMORODI: So, Ermias, do you believe that, if we radically rethink the ways we've been doing agriculture for years - in this case, the way we've been feeding livestock - that we've got at least one solution to help stop global warming?

KEBREAB: Yeah, absolutely. I think, you know, who would have thought that we are talking about a climate-neutral livestock industry? I mean, that's the kind of goal that we need to have and, you know, use it completely. Instead of saying, stop eating meat, stop doing this, stop doing that, we have to be realistic of what needs to happen. And the reality is that, you know, people are not going to stop eating meat. And so let's figure out a way in which we can help people and help the environment at the same time.

Climate change is happening and it's not waiting for anybody. We have the solution. We need to implement it because we will see the results fairly quickly. Methane - in 12 years of time, the reduction that you have now would actually translate into even a cooling of the climate. We will see that result. I believe that we can reach into a climate-neutral situation where what we eat is actually - does not have an impact on the warming of the climate.

ZOMORODI: That was Ermias Kebreab, a professor and associate dean at the University of California, Davis. You can see his full talk at

Thank you so much for listening to our show this week, Repair, Repurpose, Reimagine. This episode was produced by Fiona Geiran, Katie Monteleone, James Delahoussaye and Rommel Wood. It was edited by Katie Simon, Rachel Faulkner and me. Our TED Radio production staff also includes Matthew Cloutier, Diba Mohatasham and Katherine Sypher. Our theme music was written by Ramtin Arablouei. Our partners at TED are Chris Anderson, Colin Helms, Anna Phelan, Michelle Quint, Sammy Case and Daniella Balarezo. I'm Manoush Zomorodi and you've been listening to the TED Radio Hour from NPR.


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