Climate and the Future of Farming with Dr. Nathan Mueller

Can farmers save the planet?

We all know that the weather impacts agriculture, but farmers are also changing the weather. Dr. Nathan Mueller, head of the Mueller Lab and Assistant Professor of Earth System Science at the University of California, Irvine, walks us through cutting edge research on the complex and interesting relationship between agriculture and climate, and some of the powerful ways farmers can steer global environmental change.

The Mueller Lab:
https://www.ess.uci.edu/~nmueller/people.html

Climate Change and Agriculture:
https://www.ess.uci.edu/~nmueller/research.html

Check back soon for the new study on climate change and the future of the global beer supply!

Xie, W, W Xiong, J Pan, T Ali, Q Cui, D Guan, J Meng, ND Mueller, E Lin, and SJ Davis. in press. Decreases in global beer supply due to extreme drought and heat. Nature Plants.

 

Spring rainstorm in Iowa. Photo: Nathan Mueller

 

Episode Transcript

This is the Young Farmers Podcast. I’m Lindsey Lusher Shute. We already know that weather impacts farmers and the food system. So what will the future of farming look like in the face of climate change? To get an answer to that question, I spoke to Dr. Nathan Mueller. He works at the Department of Earth Systems Science at the University of California-Irvine. He’s studying this exact topic, how climate change and farming relate to one another, how weather influences farmers, and farmers influence the weather.

Hi, I’m Greta Zarro, organic farmer at Unadilla Community Farm and co-leader of the Leatherstocking Young Farmers Coalition in New York State. I’m a member of the National Young Farmers Coalition because NYFC provides me with a platform for connecting with fellow beginning farmers in my region. For $35 a year, you can become a member too. As a member, you’re part of a community of beginning small family farms following sustainable and fair practices. And you get discounts too like 10 percent off High Mowing Seeds. To join, go to youngfarmers.org.

Lindsey:  And Nathan, what is your area of study? And what do you do? I know your website says the Mueller Lab. That is like a group of researchers working together?

Nathan:  So I study, uh, the intersection of agriculture and global environmental change, thinking about land use, biogeochemistry, the climate system. And then I’m also thinking about the ways in which global environmental change is influencing agriculture and farmers. Um, so for example, how changes in climate are influencing crop yields and how we can adapt to those changes in the future.

Lindsey:  Can you talk about how climate change is currently impacting agriculture and what we anticipate for, for the future of agriculture? I heard you share one stat that there’s going to be an 80 percent loss of maize production by 2080 just in the US, which is pretty incredible. What are we seeing already and what does it look like, uh, going into the future?

Nathan:   So that particular stat is an interesting one to start with. There was a paper that came out about 10 years ago now, using statistical models of past weather variability and yields and they projected this potentially very large decline in the productivity of US staple crops, and the conversation has evolved since then talking about statistical modeling, so throwing a bunch of data at the problem, talking about process based modeling, so using our best understanding of how crops grow and how they respond to temperature and radiation and soil moisture. And what we see is that the picture is mixed. I wouldn’t say we’re confident about that 80 percent number. One thing that is clear is that climate change will pose a greater headwind to crop productivity. It’s unlikely, given, especially in the US, given the way that technology advances. So it’s unlikely that we’ll get net declines, but we might see that increase start to slow in the future.

Lindsey: So the productivity gains will not continue on sort of the same trajectory given the increasing challenges of growing food in certain regions.

Nathan:  Yeah, you can think of that in line of yields going up. And we actually have some new research coming out soon, fingers crossed, where we’ve looked at historical trends in climate over the US. And we’ve had this really interesting thing for corn farmers where kind of moderate temperatures have increased but extreme temperatures have have actually decreased just a little bit in the corn belt, and this seems to actually have given a little bit of a boost to yields, but looking into the future that trajectory may change as warming is projected to increase quite a lot.

Lindsey:  That’s really interesting. The reduction in extreme temperatures, do you think potentially that’s related to some of your other research on how corn and agriculture of some of these commodities is changing the weather?

Nathan:  Yeah. So, you know, when we think about climate change our default is to just think about carbon, right? The big greenhouse gas. But there are many different greenhouse gases including nitrous oxide, which, uh, you know, we see released from the use of nitrogen fertilizers for example. But you can also have a regional climate changed by land surface properties. So irrigation, when we have irrigated large swaths of land, that actually can lead to a cooling of daytime maximum temperatures. Think about, you know, when you walk into a lawn that’s just been watered or something. It feels nice and cool compared to your pavement.

Lindsey:  So this reduction- am i characterizing that right– it’s a reduction in extreme temperatures or sort of moderation because of this irrigated agriculture. And is that just in the midwest that you’re seeing that or is that something that’s happening outside of the Midwest as well?

Nathan:  Right. So is something that’s happening globally. Everywhere we have irrigation development, it influences regional climate. In the Midwest, we’ve seen it in the central valley. In places like the North China Plain and other places where a summer crops have intensified and where irrigation has developed as well.

Lindsey:   This irrigation phenomenon in moderating the climate, is this some sort of a bubble…this impact because farmers are in many cases reliant on groundwater and underground aquifers for irrigation? Is this, is this something that you anticipate will not be the case in the future as some of those supplies dwindle? Or do you think that just the techniques, even with rain fed agriculture are so much more advanced than they were at one point that this trend will continue?

Nathan:  That’s a great question. If we zoom in on the Midwest and of course as you go to the western part of the corn belt in Nebraska and the great plains, you have irrigated crop lands. But farther east, very little irrigated and in those areas to the east, when there’s a big drought, that cooling effect goes away. It evaporates, no pun intended. Um, and so yeah, you could think very similarly in the irrigated areas, if your water dries up, this sort of buffering induced by the land surface change is going to go away. In agricultural landscapes, you’ve got multiple factors influencing that regional climate. One factor, as we were just talking about, can be changes to the land surface. It can be increasing productivity of crop lands and more water use. But then we also have the influence of what we typically think about as global climate change. We have increasing greenhouse gases accumulating in the atmosphere, trapping energy and leading to warming of air temperatures and surface temperatures. So it’s kind of the balance of all of those factors that are going to drive climate into the future. And well, I think it’s fair to argue that the landscape change has had a big influence, for example, in the Midwest during the summer, the greenhouse gas signal is having a bigger effect during other seasons and at some point is going to lead to warming during the summer for those very extreme temperatures as well in the Midwest.

Lindsey:  When you say other seasons, I imagine one of the things that you’re talking about would be, for instance, in the Southwest, we’re seeing some of what would normally fall into the mountains as snow is coming as rain or the melt is happening sooner, that type of thing?

Nathan:   Definitely. Yeah. So winter is warming. In general, nighttime temperatures have been warming more than daytime temperatures and winter temperatures have been waming more than summer temperatures. And I think the snow question is a really interesting one and really critical, especially here in California, we rely so much upon the natural reservoir of snowpack. It’s pretty unclear how globally, you know, how much of our food supply is really dependent upon snow melt for water supply and what the vulnerability is in the future. But I would say it’s clearly something to worry about.

Lindsey:   Right, yeah, our western farmers are pretty concerned in the four corners area in particular just about what the reservoirs are like right now. Um, some of them didn’t get any allocation of surface water, river water this year, and they receive like 60 percent of their allocation of storage water that comes from that snow pack and the reservoir is lower going into the fall than it typically is. So that is definitely on the minds of a lot of our farmers thinking about are we going to get enough snow this winter to keep us through next summer?

Nathan:  And one thing with that is that, you know, it’s not just the average changes but also the changes in extreme events and routes that we’re really concerned about, especially multiyear droughts like we had in California recently. When these events happen year after year, it can really influence the financial viability for farmers and um, could end up pushing people out of agriculture, which is something we certainly don’t.

Lindsey:  Oh yeah, that’s absolutely true. You know, we talk about resilience oftentimes when it comes to farmers adapting and being prepared for, um, climate extremes. But there’s also like a financial viability as a big part of that as well. Like, can your business make it through those tough seasons?

Nathan: Well, I have a great postdoctoral scholar who is just starting to investigate snow melt dependence of irrigated agriculture from a global perspective.

Lindsey:  All right, excellent.

Nathan:   So we’ll let you know what we find out.

Lindsey:  You know, with climate change, there’s a couple of other elements of it that I’m curious about. Certainly out east this year we had a major hailstorm on our vegetable farm. It was a really extreme storm with like softball size hail that knocked out solar panels that are rated for golf ball sized hail, that kind of thing. I just wonder like are these sort of extreme storms that we’re seeing- is this normal or can this also be in any way associated with climate change?

Nathan:  One of the projections from the models is in fact that we will see more frequent and severe rain events, in the midwest to the northeast. And so that certainly could be related. There is a growing field within the climate science community called attribution. And the idea is that when we get extreme events that you can actually use the tools of climate science, these global climate models, and use them to characterize what the influence of climate change is on the probability of some event occurring. And as scientists we’re always very hesitant to say that anything is definitively because of climate change. What we can say is when something is more likely to have occurred because of climate change.

Lindsey:  And I’m wondering too, one of the things that I know we’ve experienced on our farm has been, um, you know, different pests and disease pressures and whatnot because of, you know, warmer winters. Um, and I’m wondering what do the climate models project in terms of disease pressure and how that is going to change nationally? Is that something that you could speak to?

Nathan:  There was just a brand new study that came out in Science which was one of the, uh, I’ll say one of the fanciest journals out there, and they did a nice job connecting climate projections with essentially pest prevalence, and they do predict that this will be a major mechanism by which agriculture is effective.

Lindsey: This is really an intriguing idea how farmers are impacting the weather. It’s a difficult thing for farmers to internalize, right? Like what a responsibility it is to actually have impact on global climate systems. To think about that and take responsibility for that I think is quite important. So I’m just wondering if you can just name all of the ways that farmers are presently impacting weather now and into the future.

Nathan:  I guess there are two main mechanisms by which farmers and agriculture in general influence the weather and our climate system. One is by influencing these biophysical mechanisms that we were talking about earlier. So for example, how much water is used on the landscape, irrigation, changes in crop productivity, and land use change. So for example, deforestation. All of these factors influence the climate from that biophysical perspective. And then the other main way that farmers and agriculture influence the climate system is through greenhouse gas emissions. Agriculture in general contributes about 25 percent of greenhouse gas emissions. About half of that is coming from land use change, uh, primarily in the tropics, deforestation and related carbon emissions. And then the other half has to do with kind of on farm management practices as well as livestock. Ruminate livestock commit methane is a greenhouse gas. Um, rice cultivation also releases methane. The use of nitrogen fertilizers releases N2o. And those are some of the big ways in which farmers influence and agriculture and food consumers such as myself influence, uh, the greenhouse gas budget of the world. It’s not fair to, you know, I don’t think we’d want to put it all on farmers, for some of these are like unavoidable consequences and they are very, I would say, difficult to deal with emissions, compared to changing power plants, etc.

Lindsey: When it comes to transition of forested land or prairie land or whatnot, and I guess a lot of this is happening right now in the tropics, can you explain what that means for greenhouse gas emissions or how that impact occurs?

Nathan: Yeah. So let’s take as an example, Indonesian Rainforest that is being cleared for oil palm. And so they’ll come in and clear the land often through burning. And so you release the carbon locked up in the above ground biomass in the trees when you burn, and then when the soil is disturbed, that also releases carbon from the soil. And then in Indonesia, there’s another interesting case where you have wetlands soils and when these wetland soils are drained, um, that increases the decomposition of the biomass that’s essentially locked up in those soils. And so, um, you can see a lot of emissions from the soils as a result of that.

Lindsey: And what about in the Midwestern context? Um, when we see a native native prairie, uh, turned into cultivated land, I suppose as an example. Are there similar greenhouse gas emissions in that scenario?

Nathan:  Yeah, exactly. Very similar mechanisms at play where you have a pulse of carbon coming from the above ground biomass and then also when that soil is tilled and worked with, um, you see emissions from below ground as well. In general, there’s this enthusiasm about focusing on soil health and how focusing on soil health can actually be a really key way to help solve the climate problem. Specifically the idea that these soils can be made more carbon-rich through management and that that sequestration of carbon can really help.

Lindsey:  Do you have a sense of like the scope of such soil health practices that would be required to really play a meaningful role in climate mitigation?

Nathan:  You know, I don’t have the numbers off the top of my head, but I will say that the researchers that have been doing field studies on this topic, they find that pretty large sequestration rates are possible on cropland and on degraded pastures. And um, and then, you know, when they do back of the envelope calculations to see, you know, how this could scale up, you do get some really large numbers. Um, the majority of countries in the world with the exception of the US have agreed to, um, you know, limit climate warming to two degrees celsius with a more aspirational goal of one and a half degrees. And it turns out that in these models, one of the only ways they can get there is if they assume there’s some way in which we’re able to actually suck carbon out of the atmosphere. So these are Called negative emissions. And one of the ways that you could get negative emissions is if you produced bioenergy and also capture the carbon and sequestered some of the carbon associated with that bioenergy.

Lindsey:   So when you say a bioenergy, it’s some sort of replacement fuel to a fossil fuel in addition to having negative emissions?

Nathan:  Right.

Lindsey: And so negative emissions would be, I guess one way to do that would be soil carbon sequestration?

Nathan: Yeah, exactly. It’s a little disturbing that, you know, the scenarios that we can come up with that allow us to meet the goals that we have stated for ourselves with climate change. But it’s another way of emphasizing the importance of agriculture in all of this, and we’ll see how it ends up.

Lindsey: Some of your work has been on farmer attitudes on climate change and what makes a farmer associate a particular, um, uh, I guess weather event or weather trend as climate change or not. Could you tell me a little bit about the work you’ve done on that?

Nathan:  Sure. So yeah, I had the opportunity to collaborate with a great researcher at the University of Vermont, Meredith Daniels. So in our specific study we were looking at actually farmers in New Zealand, um, and we were comparing perceptions about how climate was changing to how climate was changing locally in those regions. And so we saw, you know, it was really a mixed bag in that population. One thing that was interesting is that their belief and whether climate change was occurring at the global level was related to their perception of whether they thought that a change was occurring locally, and the farmers were also very accurate in capturing the fact that uh, the winter was warming a quite substantially.

Lindsey:   So if the farmers observed local events, they were more likely to believe that global climate change was occurring. Is that correct?

Nathan:   Yeah. So, uh, it was actually, if they believe that global climate change was occuring–

Lindsey:   Oh, ok, I’m wrong. It’s the other way around–

Nathan:  –they were a bit more likely to perceive the local change. Yeah. Which was really interesting. We also saw that you know, for some of the perceptions, like for example, with the winter warming were certainly right on, which tracks with the fact that who’s going to be a better observer of weather and climate than farmers.

Lindsey:   So you’re finding is that if a farmer believes that global climate change is happening, they would associate weather anomalies or winter warming or whatnot also with that climate belief.

Nathan:  Their beliefs were associated with their perceptions of local change for sure. Um, but, uh, some of the perceptions definitely tracked the local changes. And here in the US, um, my understanding of the latest research on this is that across the country a majority of farmers do believe that climate change is happening and is likely to affect them. But, um, there is still less than half that believe it to be anthropogenic.

Lindsey:  How much should we use that data in thinking about encouraging and working with farmers to get more of them engaged in these efforts on climate mitigation?

Nathan:                     That is a really, really interesting question and I’m not sure I have a perfect answer for you. Uh, but certainly some practices that might be considered an adaptation to climate change may just be also something that’s good for the soil. It’s good for the bank account and so whether the motivation is fundamentally about climate change or the weather, it may or may not matter as much once you get down to actually just adopting certain practices that are going to be beneficial for the farmer.

Lindsey:   Yeah it’s something that I’ve thinking a lot about since hearing experts say that they need farmers to play such an important role, but also knowing that farmers aren’t necessarily aware of what’s expected of them or hoped for their practices. And I feel like there’s a sort of a fundamental disconnect there, broad scale or maybe just on farm scale. Like what are the top things that could change, particularly with US agriculture, that would really make a significant difference?

New Speaker:  Yeah. So I think all this research coming out about soil carbon sequestration is really key. We also see that nitrous oxide is emissions from nitrogen fertilizer use, but inorganic and organic sources, of course. We also see nitrous oxide from organic nitrogen sources. Managing nitrogen, increasing nitrogen use efficiency, promoting precision agricultural technology are all means by which we can help reduce those emissions. One way that we can influence greenhouse gas emissions as food consumers is through how much room and meat we consume. And this becomes a little tricky. I think it’s hard too because, you know, I have relatives that raise cattle and there are livelihoods and cultures, uh, associated with meat production. And so I don’t know, it’s a hard conversation to have.

Lindsey:   So some of that is reducing meat consumption, but also, we have more people, right? So if we even just stay at the level we’re at now, that’s less meat per person.

New Speaker:  The key thing here is like if in the developed countries, our diets are a little bit less than intensive, you know, we also have massive population growth, massive increases in the richness of diets. In the developing world, increasing meat and dairy consumption. So I don’t think we’re talking about like a net negative decline in meat and dairy globally, by any means. But at least, that is a lever that can be pulled on to have an influence.

Lindsey:  And I know this isn’t your specific area of study, but when you say ruminant agriculture, there is a difference between ruminants that are grown in a confinement situation and those that are raised on pasture in terms of methane emissions.

Nathan:  Yeah. So I’m not familiar with all of the details of that work. I know that it matters, you know, what the rates of emissions are. And there was some recent work suggesting that the grass-fed impacts are actually a little bit larger.

Lindsey:  Because of the length of time to raise a given animal.

Nathan:  Exactly. Yeah. So I think one bigger picture thing that I’ve found since getting into this topic from an academic perspective is that it’s difficult because we all come from different backgrounds and have different ideas about, you know, what we think sustainable looks like or ought to look like, and you find yourself sort of humbled over and over where you know, you realize maybe your perceptions weren’t right and you have to reevaluate in the face of evidence. You know, for example, in the case of this greenhouse gas emissions of grass fed cattle thing, it was a surprise to me.

Lindsey:   Is there a tendency to just look at all of that carbon emissions narrowly too, as opposed, you know, like you think of a pasture based system as being very healthy for the ecosystem as well, that it supports, whereas a confinement operation is dramatically altering that ecosystem to support growth of animals and livestock. So I think it’s really interesting to see what that carbon balance is, but what is being missed in that conversation?

Nathan: That’s a great point. Yeah. Even though we, you know, need to bring numbers to bear on all of these issues, it’s really important not to look too narrowly and to consider all of the dimensions of the system, all of the services that are being produced by that landscape, and the impacts of how it’s managed. And in research about ecosystem services as a little subfield of environmental science where we’re talking about how the services provided to humans of different landscapes– they often have these plots that are like flower petals. And each petal encompasses some dimension that we care about. So you know, one could be greenhouse gas emissions, one could be biodiversity for example. Something that’s nice about that is you get this nice visual picture of how these different landscapes compare. You can see what it looks like and not just go down to one particular axis but look at a bunch of different outcomes together and that’s a nice framing to keep in mind.

Lindsey:  There is so much complexity to all of this and I think there is no choice but to embrace that complexity. Right? Because ignoring any part of it, I think–

Nathan:  Exactly, I think that’s very true.

Lindsey:  You know, not just this narrow sort of carbon balance equation when you’re thinking about um, raising livestock, but also just like thinking about how we get more farmers engaged in climate mitigation. We’re like attitudes and cultural beliefs and you know, regional practices, etc. like how that plays into economic variables and I don’t know, the list goes on and on and on. But yeah, these are the conversations we need to be having and as challenging as they may be, because the climate impacts, it’s happening now.

Nathan: Absolutely.

Lindsey:  Nathan, thank you so much for joining us today. I learned a lot.

Nathan:  Thanks so much for having me.

Lindsey:  Thanks so much for your time. Dr. Mueller, thank you so much for being on the show and for explaining so much. I have to mention that Nathan Mueller is also a coauthor on a new paper on the impacts of climate change on the global beer supply. We will link to that paper in the show notes as well as some of his other research. If you like what we’re doing here on this show, please leave us a note on iTunes. It really does help more people find the pod. This show is edited by Hannah Beal and recorded with the generous help of Radio Kingston. See you next week.

 

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