Asmeret Asefaw Berhe: How can soil's superpowers help us fight climate change? Earth's soil can store vast amounts of carbon. Biogeochemist Asmeret Asefaw Berhe says soil could be a powerful tool for fighting climate change - if only we stopped treating it like dirt.

Asmeret Asefaw Berhe: How can soil's superpowers help us fight climate change?

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MANOUSH ZOMORODI, HOST:

As we just heard, Katrina wants to make burials more eco-friendly by harnessing soil's power to decompose a body and then hold on to the carbon that gets released, keep that carbon underground. This process is called carbon sequestration, and our next speaker says it could be used to solve the biggest problem that our planet faces.

ASMERET ASEFAW BERHE: The health of the soil system is extremely important part of addressing the climate crisis.

ZOMORODI: This is Asmeret Asefaw Berhe.

BERHE: I'm a professor of soil biogeochemistry at the University of California Merced.

ZOMORODI: Asmeret has been studying dirt for decades.

BERHE: The hook for me happened when I realized how important soil is in regulating life as we know it in the Earth's system.

ZOMORODI: And the more Asmeret learned about soil, the more she realized that we humans were squandering its superpowers. Here she is on the TED stage.

(SOUNDBITE OF TED TALK)

BERHE: Climate change happening because of the increasing amount of greenhouse gases we keep releasing to the atmosphere. You all know that, but what I assume you might not have heard is that one of the most important things our human society could do to address climate change lies right there in the soil. Human actions are now releasing 9.4 billion metric tons of carbon to the atmosphere. But the concentration of carbon dioxide that stays in the atmosphere is only increasing by about half of that. And that's because half of the carbon we keep releasing into the atmosphere is currently being taken up through a process we know as carbon sequestration. So in essence, whatever consequence you think we're facing from climate change right now, we're only experiencing the consequence of 50% of our pollution. But don't get too comfortable. The ability of these natural ecosystems to take up carbon dioxide from the atmosphere and sequester it in the natural habitats is currently getting compromised as they're experiencing serious degradation because of human actions.

We treat soil literally like dirt. We haven't been taking care of the soil, even though soil has actually been making our lives possible.

ZOMORODI: In a moment, more from Asmeret Asefaw Berhe on the climate change solution that's right beneath our feet. I'm Manoush Zomorodi, and you're listening to the TED Radio Hour from NPR. We'll be right back.

(SOUNDBITE OF MUSIC)

ZOMORODI: It's the TED Radio Hour from NPR. I'm Manoush Zomorodi. On the show today - What Lies Beneath. We were just talking to Asmeret Asefaw Berhe, a soil scientist at the University of California.

BERHE: I love soil in all forms. I think soil is just beautiful.

ZOMORODI: Asmeret says that soil is one of our best tools for fighting climate change because it can store vast amounts of carbon. Here she is again on the TED stage.

(SOUNDBITE OF TED TALK)

BERHE: There is about 3,000-billion metric tons of carbon in the soil. That's roughly about 315 times the amount of carbon that we release into the atmosphere currently, and there's twice more carbon in soil than there is in vegetation and air. Think about that for a second. There's more carbon in soil than there is in all of the world's vegetation, including the lush tropical rainforests and the giant sequoias, the expansive grasslands, all of the cultivated systems and every kind of flora you can imagine on the face of the Earth - plus, all the carbon that's currently up in the atmosphere combined and then twice over. Hence, a very small change in the amount of carbon stored in soil can make a big difference in maintenance of the Earth's atmosphere.

But soil's not just simply a storage box for carbon, though. It operates more like a bank account. And the amount of carbon that's in soil at any given time is the function of the amount of carbon coming in and out of the soil. Carbon comes into the soil through the process of photosynthesis when green plants take carbon dioxide from the atmosphere, and upon death, their bodies enter the soil. And carbon leaves the soil and goes right back up into the atmosphere when the bodies of those formerly living organisms decay in soil by activity of microbes. One of the things that makes soil such a fundamental component of any climate change mitigation strategy is because it represents a long-term storage of carbon. Carbon that would have lasted maybe a year or two if it was left on the surface can stay in soil for hundreds of years, even thousands and more.

ZOMORODI: So soil has this amazing capacity to store carbon. But we humans have been messing with the soil, and in your talk, you say that half of the world's soils are considered degraded. Is that one of the reasons why we have a warming planet, because we've damaged the soil so it can't take in as much carbon as it used to and as much as we need it to?

BERHE: Yeah. So human actions - in particular, the way we've changed land use and land cover globally, including through deforestation and intensive cultivation practices - they typically contribute about 15% of the CO2 that we keep releasing into the atmosphere every year. So...

ZOMORODI: Wow.

BERHE: ...It's a big portion of the CO2 we keep releasing into the atmosphere. Carbon that would have stayed in the soil system is not staying, is rather going back into the atmosphere as greenhouse gases because we keep cutting down the trees, we keep over-tilling the soil and disturbing the soil to a point where its ability to hold on to that carbon is diminishing. And since the, you know, human community started engaging in agriculture in a large-scale manner, we've released on the order of about 120 billion metric tons of carbon that was in soil into the atmosphere.

ZOMORODI: Oh, wow.

BERHE: Yeah. So and this - the fastest rate of loss has been happening in the last 200 years since the Industrial Revolution. So remember that the most important ways we use soil as human community is for supporting plant productivities, but we also build the infrastructure, right? It's where we build our roads and bridges and everything, and those are the part of the processes that are responsible for the large-scale degradation of soil globally. Close to half of the soils in the world right now are considered degraded, meaning their ability to support plant production and to support life is compromised.

ZOMORODI: So that means, like, all the rainforests that have been cut down and all the millions of heads of cattle that are grazing on plains - all of that means that the soil underneath is not as rich as it once was.

BERHE: Yeah. And all of these intensive deforestation and grazing practices, in particular over-grazing beyond the capacity that the land can support - all of that compromises the physical stability of soil, the chemical nature of soil, including provision of the nutrients that are needed to support the microbial communities. So this is why it becomes really important to think about managing soils in a climate-smart way.

(SOUNDBITE OF TED TALK)

BERHE: Fortunately, I can also tell you that there is a solution for these two wicked problems of soil degradation and climate change, and the solution lies in simultaneously working to address these two things together through what we call climate-smart land management practices. And we can accomplish this by putting in place deep-rooted perennial plants, putting back forests whenever possible, reducing tillage and other disturbance from agricultural practices, including optimizing the use of agricultural chemicals and grazing, and even adding carbon to soil whenever possible from recycled resources such as compost and even human waste.

This kind of land stewardship is not a radical idea. It's what made it possible for fertile soils to be able to support human civilization since time immemorial. In fact, some are doing it just right now. There's a global effort underway to accomplish exactly this goal. This effort that started in France is known as the 4 per mille effort, and it sets an aspirational goal to increase the amount of carbon stored in soil by 0.4% annually, using the same kind of climate-smart land management practices I mentioned earlier. And if this effort's fully successful, it can offset a third of the global emissions of fossil-fuel-derived carbon to the atmosphere.

But even if this effort's not fully successful but we just start heading in that direction, we still end up with soils that are healthier, more fertile, are able to produce all the food and resources that we need for human populations and more, and also soils that are better capable of sequestering carbon dioxide from the atmosphere and helping with climate change mitigation. I'm pretty sure that's what politicians call a win-win solution.

ZOMORODI: Wow. OK, so if we could reduce our CO2 buildup by a third just by focusing on soil, Asmeret, why aren't we talking about that in the same breath as how we're going to save our oceans or making sure that the polar ice caps don't melt away?

BERHE: I think in some ways it's because we had grown so accustomed to take soil for granted. And part of this is because the group of people that are affected and the group of people who have been addressing it have been two distinct groups, right? And I personally feel it's important to highlight the human element of this discussion because, in many ways, a lot of the impacts of climate change are going to be felt by, economically speaking, the least fortunate amongst us - the folks who live in poor nations, you know, small island nations near the equator in coastal margins. But their voices and especially until recently had not been part of our climate conversation. And the fact that climate change has become a threat multiplier - i.e. it's actually exacerbating the problem of food and nutritional insecurity, water insecurity in many parts of the world - had not gotten enough attention in our discourse.

ZOMORODI: So you're saying that, you know, if there was more diversity in the people who are calling attention to all these climate change problems we have and the potential solutions that more people might understand the role that soil plays, which would in turn help us all.

BERHE: Exactly. Yeah. In many cases, it's like whenever we have more diversity in science, we end up addressing societally relevant questions, right?

ZOMORODI: Yes, that is correct.

(LAUGHTER)

ZOMORODI: You know, I'm sitting here, and I'm thinking about how rarely I actually touch soil. I live in a city. I go to the park all the time. But when was the last time I actually felt the dirt? Not recently.

BERHE: Yeah. Yeah, I think that's true, right? Human communities evolve in agricultural societies, where they were intimately aware of the land around them, its properties, and they knew what it could support and what it couldn't. And they work the land, literally speaking, to support their livelihood. Many of us in modern times don't have that connection, and in many ways, we've lost the connection to a point where soil is just the stuff beneath the asphalt or the concrete that we step on every day, right? It's not even the thing we experience, unless we're out hiking in the trail somewhere or in a park. And so that connection is lost.

(SOUNDBITE OF TED TALK)

BERHE: We all can have a role to play here. We can start by treating the soil with the respect that it deserves - respect for its ability as the basis of all life on Earth, respect for its ability to serve as a carbon bank and respect for its ability to control our climate. And if we do so, we can then simultaneously address two of the most pressing global challenges of our time - climate change and soil degradation. And in the process, we would be able to provide food and nutritional security to our growing human family. Thank you.

(APPLAUSE)

ZOMORODI: Asmeret Asefaw Berhe is a soil scientist at the University of California, Merced. She's also President Biden's pick to lead the Department of Energy's Office of Science. You can find her full talk at ted.com.

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