Third Pod Live: The Dirty Links between Soil and Climate

Asmeret Asefaw Berhe is a Professor of Soil Biogeochemistry at the Life and Environmental Sciences unit, University of California, Merced. She received her PhD in Biogeochemistry from the University of California, Berkeley; M. Sc. in Political Ecology from Michigan State University, and BS in Soil and Water Conservation from University of Asmara, Eritrea. She is a recipient of numerous awards including the National Science Foundation’s CAREER award, the Young Investigator Award from Sigma Xi, and the Hellman Family Foundations award for early career faculty.

Basically, she rocks. 

Her research focuses on biogeochemical cycling of essential elements (esp. carbon and nitrogen), in particular in systems that experience physical perturbations (ex. erosion, fire, changes in climate). At the AAAS 2019 annual meeting in Seattle, we had a chance to sit down with her for a live interview where we talked about soil (not dirt), bribing lab mates to help with experiments, looking to the ground to mitigate climate change, and more!

This episode was produced by and mixed by Shane M Hanlon. 


Shane Hanlon (00:00):

All right. So I wanted to… Oh, I guess I should say hi. Hi, Nanci.

Nanci Bompey (00:06):

Hi, Shane.

Shane Hanlon (00:09):

If things sound a little bit different from us, we are recording from our collective homes. You can hear background noise here and there. We also have Liza with us. Hi, Liza.

Liza Lester (00:20):

Hey, guys.

Shane Hanlon (00:21):

Okay, so today I want to talk about dirt and being dirty. What’s the dirtiest thing you’ve ever done? What’s like the dirtiest you think you’ve ever been?

Nanci Bompey (00:34):

I’ve been backpacking for two weeks without showering, pretty dirty.

Liza Lester (00:42):

I get dirty backpacking.

Shane Hanlon (00:44):

I wasn’t even thinking about like grody dirty. I was thinking about legit dirt.

Nanci Bompey (00:47):

Oh, like-

Shane Hanlon (00:49):

Oh, no, but I’m fascinated by this.

Liza Lester (00:50):

Just mud covered.

Shane Hanlon (00:50):

Where were you?

Nanci Bompey (00:51):

Yeah, my hair in Colorado was just a matted clump by the end. Oh, so disgusting.

Shane Hanlon (01:00):

That’s not good.

Nanci Bompey (01:03):

In the current situation as we’re all at home quarantining currently, Richard, my boyfriend isn’t showering so often, so that’s been an interesting situation, the dirtiness. I have to remind him.

Shane Hanlon (01:17):

That’s lovely.

Liza Lester (01:18):

To shower?

Nanci Bompey (01:19):

Yeah. So that’s not so fun.

Shane Hanlon (01:24):

Liza, what about you? Do you have anything that pops to mind?

Liza Lester (01:27):

When I was a kid, our backyard, from a previous owner who apparently didn’t like to garden, he just created half cement patio and half this enormous sandbox, huge-

Shane Hanlon (01:38):

Oh, interesting.

Liza Lester (01:39):

… which was amazing. And I just liked to dig holes. I think as a child I would just dig holes and I’d fill them with water or make mud volcanoes using the hose.

Shane Hanlon (01:49):

That’s amazing.

Liza Lester (01:50):

It was over and over. I guess it was my early forays into geology.

Shane Hanlon (01:56):

Yeah. Oh, there you go.

Nanci Bompey (01:58):


Shane Hanlon (01:58):

There you go. I was thinking-

Liza Lester (02:00):

I think my dad thought it was disgusting. He was just like, “You’re sitting in a giant cat box.”

Shane Hanlon (02:05):

Talking about disgusting, we’ve talked to… I’m not going to go into it, but mine would be falling into the septic tank. We’ve talked about that before.

Liza Lester (02:13):


Nanci Bompey (02:15):

Oh, I believe we have. I believe we have.

Shane Hanlon (02:15):

Yeah. In rural America, it turns out that people aren’t really up to code, and so one time I fell into an open septic tank when I was in my mid-teens. There’s not enough bleach in the world to fix that.

Shane Hanlon (02:29):

Welcome to the American Geophysical Union’s podcast about the scientists and the methods behind the science. These are the stories you won’t read in the manuscript or hear in a lecture. I’m Shane Hanlon.

Nanci Bompey (02:39):

And I’m Nanci Bompey.

Shane Hanlon (02:41):

And this is Third Pod from the Sun.

Shane Hanlon (02:45):

All right, we said as we recorded the intro, we should have said “quarantine edition” or isolation.

Nanci Bompey (02:54):

I think it is.

Shane Hanlon (02:54):

Or isolation, yeah.

Nanci Bompey (02:56):

Isolation edition.

Shane Hanlon (02:57):

Right. Our habits are all changing, I guess, including some of our hygienic habits, as it were. I am just as guilty in all of this, as well. But actually the reason why I was asking you all of this is because we have today… Liza and I actually talked with a soil scientist at the AGU Annual… Oh, not AGU, excuse me, at Triple AS’s meeting back in February. It’s the end of April now, and it seems like forever ago.

Liza Lester (03:32):

That’s right.

Nanci Bompey (03:32):

It was a different time ago. It was a different time ago.

Liza Lester (03:35):

We were in Seattle.

Nanci Bompey (03:36):


Shane Hanlon (03:36):

We were on planes and traveling around the country.

Liza Lester (03:38):

In February. The epicenter.

Shane Hanlon (03:40):

Yeah. But we had this great opportunity to do this live interview.

Asmeret Asefaw Berhe (03:47):

I’m Asmeret Asefaw Berhe. I’m a professor of soil biogeochemistry at the University of California Merced.

Shane Hanlon (03:52):

So Asmeret is a soil scientist and, frankly, a bit of a badass. She started her career in political ecology where she looked at how various war zones affected ecosystems.

Nanci Bompey (04:05):


Shane Hanlon (04:05):

Yeah, I know. It’s ridiculous.

Nanci Bompey (04:07):

It’s interesting.

Shane Hanlon (04:08):

And we actually, we’ll tag this in the notes, though I actually have a story from her where she talked about this at one of our meetings. But since then she’s transitioned from that to now climate and soil, and that’s where we started this conversation.

Shane Hanlon (04:25):

You were saying about soil and climate. How did you come to bring these things together? Was soil first? Was climate? What was that progression to get you where you are today?

Asmeret Asefaw Berhe (04:39):

Soil was definitely first for me. I was an undergraduate soil science major at the University of Asmara in Eritrea before moving to the US, and I had studied soils, in particular questions about soil degradation by human activities for a long period of time. And then as I was starting a PhD program in Berkeley, focus, in particular thinking about questions around soil use and degradation by human actions, I started learning more and more about climate change, and we’re talking about around 2000 now, where these topics were everywhere. And I was particularly interested in thinking about the connection between soil degradation and climate change and that ended up being my PhD research. And that’s a large part of the work that we do in my lab still is questions around that.

Liza Lester (05:33):

What is your field research like? Do you get out and get dirty?

Asmeret Asefaw Berhe (05:37):

Yes, we do. So we’re soil scientists. We like, obviously, thinking and looking at soils around the world and finding all sorts of examples of soils that occur in different parts of the world and how they’re different in terms of their physical and chemical properties, but also the microbial communities that reside in the soil.

Asmeret Asefaw Berhe (06:01):

Yeah, obviously, if you’re going to do the kind of work that we do, it involves digging a lot of cores, or sometimes we like pits, preferably we like pits. We dig large pits, we get inside and we look at the soil and we sample it and that involves getting dirty. But we’re pretty good with getting dirty.

Liza Lester (06:20):

You like it? Does soil in different parts of the world smell different? Does it feel different?

Asmeret Asefaw Berhe (06:26):

Oh yes, completely. So soil around the world is very, very different depending on a combination of factors. So depending on what type of climatic zone we’re talking about or what kind of parent rock the soil is formed from, the different influences that living communities can have, and even topography in influencing the movement of top soil and water, and how long a soil has been, basically, exposed to the elements and how long it’s been changing.

Shane Hanlon (06:59):

I’ve never learned as much or appreciated different soils so much. And I have to ask you, it seems like you’re very deliberate about saying soil and soil and, and I wonder if there’s… When you tell people what you do, regardless of the climate part, they probably, in their minds, they’re like, “Oh, you work with dirt.” Right? Is there a jargon thing there that it’s very important to say soil, or do you care when folks are “dirt”, or what goes through your head when someone’s like, “Oh, you work with dirt.”

Asmeret Asefaw Berhe (07:30):

So I’m definitely one of those soil scientists who really do not like that word, the “d” word. And part of this is because I think soil is so important and precious natural resource that’s really critical for the Earth system and how it functions and all the roles that it plays on our behalf, and maintenance of life in general on the Earth system, that I am very opposed to people calling it dirt.

Asmeret Asefaw Berhe (07:57):

Whenever I go and give public lectures, in particular, or lectures in schools with K to 12 students, before I give them the official definition of soil, I typically ask them, what’s the first thing that comes to your mind when you’re going to hear that I’m, myself as a soil scientist, is going to be talking to you all? And inevitably, always, the responses I get center around dirt. Right? And then I have to work to, basically, get rid of that kind of thinking as much as quickly as possible. I try to give them the dictionary definition of what that word dirt means.

Asmeret Asefaw Berhe (08:39):

Dirt is something that’s unneeded, unclean, a nuisance, something that’s just troublesome that you want to get rid of. Right?

Liza Lester (08:46):

Like a pejorative to our soil-

Shane Hanlon (08:48):


Liza Lester (08:48):

Hurts its feelings.

Asmeret Asefaw Berhe (08:50):

Yeah, and so I feel like soil is the furthest thing away from that. There’s, literally, no life in the air system without soil. Our climate would not be maintained the way it is without soil. We won’t get the kind of water amount or quality that we need without soil. It’s a critical element of how we build our dwellings and infrastructure, and it is also the place where we find the most abundance and diversity of life. There’s, literally, nowhere else in the earth system that you could go to find the kind of abundance and diversity of life that soil has. That’s a long-winded way of saying that I really don’t like that “d” word.

Shane Hanlon (09:27):

No. No, this is good. This is good. I never really considered that.

Shane Hanlon (09:32):

Okay. So Nanci or Liza, is there anything in your professional life or previous lives as researchers where folks would use dirt versus soil, where they’d use a wrong phrase or more flippant about the word usage and it really bothered you?

Nanci Bompey (09:54):

I don’t know when I was doing science, but when I went to journalism school you get the grammar drilled into you. You guys probably know this… Well, Liza probably does because she’s very “grammarly” I feel.

Shane Hanlon (10:07):


Nanci Bompey (10:07):

But did you know that it’s champing at the bit, not chomping at the bit.

Shane Hanlon (10:13):

Oh, I didn’t.

Nanci Bompey (10:14):

Did you know that? It’s champing.

Liza Lester (10:17):


Shane Hanlon (10:17):

What the heck?

Nanci Bompey (10:17):

Very few people know that.

Shane Hanlon (10:18):

What does that mean?

Nanci Bompey (10:19):

I don’t know, but it’s not chomping.

Shane Hanlon (10:22):

Oh, man. All right. I’m going to have to go down a word wormhole after this.

Nanci Bompey (10:27):

But a lot of things like that were drilled into me that, probably not to a good degree, but, yeah.

Shane Hanlon (10:31):

Yeah. I remember when I was in grad school, there was a scientist who studied epigenomics or something of beetles, and… I don’t know what epigenomics are, but I do know that he got very, very upset when we called them bugs. He would say, “They’re not bugs, they’re beetles.” I will never forget.

Liza Lester (10:53):

Entomologist. Strong feelings.

Shane Hanlon (10:55):

Yeah. Yeah, he’s a rock star, but, yeah, he had very strong feelings. So in this interview, after we had this long discussion about dirt, and actually we cut some of it out. It’s a great discussion, but we could have done an entire podcast on it. We shifted to talking about her field experiences and whether she ever had any noteworthy highs or lows.

Asmeret Asefaw Berhe (11:17):

Whenever you do field work, in particular, but even lab work, there’s all sorts of interesting challenges and logistical nightmares that you have to deal with. Some of my memorable events in field work, probably one that stands out for me, is, for example, when I was a graduate student, I decided to do this ambitious project where I was going to figure out how fast organic carbon cycles in soil and how that varies, depending on topography of the landscape. I set this experimental design that included digging two by three holes and that are a meter deep. That’s a lot of soil.

Shane Hanlon (11:58):

Two by three meters?

Liza Lester (11:58):

That’s a lot of holes.

Asmeret Asefaw Berhe (11:58):

Two by three meters.

Shane Hanlon (11:59):

Oh, wow.

Asmeret Asefaw Berhe (12:00):

And then a meter deep because I needed them to do the decomposition experiments that I wanted to set up. And, thankfully, I had a lot of friends, so I recruited 18 friends to get out to the field with me. And we’re doing this and we’re working really hard. You can imagine how much digging that is for people.

Shane Hanlon (12:20):

How many holes?

Asmeret Asefaw Berhe (12:22):

There was in total four holes of this size that we had to dig in one small catchment between 18 of us.

Shane Hanlon (12:29):


Asmeret Asefaw Berhe (12:30):

But it just happened to be the day that we went that it had rained recently, so we’re digging and emptying this hole as fast as we possibly could. But we’re in a hill slope so water keeps coming and coming, so we’re not just getting dirty, we’re getting very muddy. So there’s interesting challenge like that.

Asmeret Asefaw Berhe (12:56):

But looking back at it now some 13, 14 years after this experiment was done, it was a very smart thing to do, rain or [inaudible 00:13:06]. Not having rain would have been helpful, at that time at least, but it was interesting. And so there’s interesting challenge like that that you have to deal with. Looking back we just laugh about it. Right? And, thankfully, we were all excited about the project and to help one another, so this was possible.

Liza Lester (13:27):

How do you convince your 18 friends? Like, “We’re going to go dig some holes. It’s going to be really fun. I’ll buy you some pizza.”

Shane Hanlon (13:33):

Right. Are these all other grad students who understand that resources are limited and I help you, you help me, or…

Asmeret Asefaw Berhe (13:40):

Basically, exactly that. Graduate students and postdocs, some of them from my advisor’s lab, some of them friends around campus, and a couple from a nearby research institution that we knew. But all of them are, either graduate students or postdocs in different fields in earth and environmental sciences, that are working on this topic. So they did understand the challenge and they did appreciate what I was trying to do, which is helpful, obviously.

Liza Lester (14:07):

Tell them it’s CrossFit.

Shane Hanlon (14:08):


Asmeret Asefaw Berhe (14:08):

But now I have pictures many years later to show of how dirty we got and how interesting that day was. But yeah, you just, basically, help each other and the cost to me is just the cost of sandwiches for lunch and snacks, and that’s really it.

Shane Hanlon (14:24):

Did the design work?

Asmeret Asefaw Berhe (14:26):

It worked.

Shane Hanlon (14:26):


Liza Lester (14:26):


Asmeret Asefaw Berhe (14:26):

Yeah. Led to multiple papers.

Shane Hanlon (14:28):

Oh, all right. So that’s not bad.

Liza Lester (14:30):

Worth all that whole day.

Asmeret Asefaw Berhe (14:32):

Yes, especially three papers that it became an integral part. In hindsight, it was not a bad idea. It was a really good one, but it was not easy.

Shane Hanlon (14:41):

I can definitely relate to this idea of bribing lab mates for food. When I was a grad student, I did a lot of my field work at this field station in Memphis in the middle of the summer, and it’s a gajillion degrees, so usually we would start really early in the season, like February and go till June, so we missed the worst parts of the summer.

Shane Hanlon (15:01):

But one of my lab mates didn’t quite have his act together and so he started in May and ended up going through August, where we had an entire month where it didn’t get below a hundred degrees, and I was kind enough to assist him. But the trade-off was that every single morning we’d get up at five in the morning, before dawn, and we’d go to this biscuit place and he’d buy me a ham and cheese biscuit sandwich every single morning for about a month.

Shane Hanlon (15:29):

I helped him and he was very happy for that, but on the flip side of it, I think I gained a little bit of weight that summer, just from being bribed by the sandwich.

Nanci Bompey (15:41):

Yum. Ham and cheese biscuit sounds good.

Liza Lester (15:43):

Mm-hmm (affirmative).

Shane Hanlon (15:43):

Oh, yeah, frankly, it was worth it. I hate summer, but I would definitely say it paid off. Okay. So back to the interview.

Shane Hanlon (15:55):

As we finish up, we have a few more minutes. The last thing I wanted to ask you about is soil climate, the intersection there. Do you have any practical advice as to how we, the royal we, could do things to mitigate climate change, or whatever the word choice you want to use, from a soil perspective?

Asmeret Asefaw Berhe (16:16):

Yeah, I do and I think a lot of this starts with educating ourselves about how the earth system really functions as a connected system where the different pieces are interrelated to one another and they actually influence one another. So what we do in soil matters for climate, and what we do with the climate system also has implications for soil and it all feeds back, basically, in a cycle. So if we’re going to think about climate change, I think there are a couple of things we have to do. Right?

Asmeret Asefaw Berhe (16:49):

One, obviously, most importantly, we need to think about reducing emissions. And I do not want to bring any question about carbon sequestration and soil ahead of reducing emissions. I think that has to be clear. But once we think about reducing emissions or at the same time that we’re doing that, then we have to think about how do we capture some of that carbon dioxide that’s continuously making it into the atmosphere and make it possible for it to enter the terrestrial system so the biomass in vegetation, for example, and preferably in soil. And that’s really important and key to our climate future, because if we can do that, if we could do both of these things, then we now have a real shot of not just reducing the rate at which carbon dioxide concentration in the atmosphere, or greenhouse gas concentration, is increasing, but we actually have a shot at bending the curve and even going below the current levels of greenhouse gas concentrations in the atmosphere.

Asmeret Asefaw Berhe (17:52):

And this includes the practices that we mentioned earlier, right? Reducing the disturbances that cause large amounts of carbon to be released from soil to the atmosphere, including practicing conservation, agriculture, regenerative agriculture, if you will, and making sure that we’re not tilling the soil as much as it’s currently being tilled. Putting back forest whenever possible, putting back grasslands whenever possible, depending on which part of the world and which kind of climate envelope we’re talking about.

Asmeret Asefaw Berhe (18:26):

There’s a balance between whether it’s forest or grasslands that are favored, and both can help with carbon sequestration under the right environmental conditions, in particular with the right management. So thinking about both natural and working lands from the perspective of managing them in a climate-smart manner to increase the amount of carbon stored in soil is key.

Asmeret Asefaw Berhe (18:48):

Along with that has to come with reduced use of agricultural chemicals. We have to figure out a way to reverse the current trend of high rates of erosion that’s occurring globally and the high rates of soil degradation, and doing so has the important benefits of not just improving soil health for the sake of climate, but also improving soil health in a way that will make positive contributions towards providing food and nutrients for the growing human population.

Shane Hanlon (19:23):


Liza Lester (19:24):

So I’m hearing you want to put carbon back where it can do good.

Shane Hanlon (19:27):

Right? Exactly.

Asmeret Asefaw Berhe (19:28):

Exactly. Yes.

Shane Hanlon (19:29):

Exactly. I love that. This is great. I’ll think about climate solutions differently, and instead of, yeah, looking up into the sky and thinking about gasses and pollutants, think about what the earth can do for us and the soil. All right, folks. That’s all from Third Pod from the Sun.

Nanci Bompey (19:49):

Thanks so much to Shane and Liza for bringing us this story and to Asmeret for sharing her work with us.

Shane Hanlon (19:56):

This podcast was produced and mixed by me.

Liza Lester (20:01):


Shane Hanlon (20:03):

Thanks, Nanci.

Nanci Bompey (20:06):

And if you love this podcast, which I am sure you do, please rate and review us on Apple podcasts. You can listen to us wherever you get your podcasts. and keep listening.

Shane Hanlon (20:18):

Yeah. Thanks all and we’ll see you next time.


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