Ep 75: Irrigation, Evapotranspiration, and Climate

A conversation with Professor Sonali McDermid (New York University) about irrigation, evapotranspiration, and impacts on climate systems. Released October 24, 2025.

Transcript

Mallika Nocco: 0:09

Welcome to Water Talk. Today we are talking about irrigation and evapotranspiration and climate. These are topics that are dear to my heart. As many of you may have gathered, I study evapotranspiration and I study irrigation. But I think about these things at kind of the soil plant water scale. I think of the scale of a farm, I think of the scale of a region. But we are going to talk about these things with Professor Sonali McDermott, who is an associate professor and the chair of the Department of Environmental Studies at NYU. So Sonali is a climate scientist. So she specializes in atmospheric science and climatology. We are going to talk with her about how irrigation can shift climate patterns and how we can think of irrigation as kind of a driver of different patterns in the climate. And this is to me really interesting because it's at a very different scale than the scale that I study. This episode, I should say, was going to be released in a different way as a part of this fellowship that I was awarded, which is called the Science Communication Identities Project Fellowship or SCP. The Scicom Identities Project was a really valuable experience for me. It was amazing. It was focused on helping early career faculty of color embrace and engage in science communication that also represented their identities. And I made a bunch of amazing connections with other professors around the country. This is unfortunately one of the fellowships and NSF-funded projects that was suspended after January 2025. So I wasn't able to complete one of the products for that fellowship, which was going to be a podcast episode, but it was going to be kind of a different kind of podcast episode than what we usually do on Water Talk. It was going to be kind of more artsy. So I'm not releasing the artsy version of that, but I am going to release the amazing interview that we did with Sonali because the topic is so interesting and important. I also want to mention that this particular podcast episode was peer reviewed by two anonymous peer reviewers. So I want to thank the two peer reviewers that offered suggestions and their time to review the material in this podcast. A couple of primer things because we're talking to a climate scientist. One of the things that comes up is atmospheric circulations. So a good thing to know is that an atmospheric circulation transports heat over the surface of the earth, and this affects the water cycle, including the forming of clouds and also precipitation. So that's kind of one atmospheric science term that you'll hear Sonali mention. Another atmospheric science term that comes up is advection. And in this case, we're talking about moisture advection. And this is the transport of moisture by winds, often horizontal winds. And finally, I think it'd be good to define evapotranspiration, which is kind of my life. Evapotranspiration is the evaporation from leaf surfaces and stem surfaces and soil surfaces. And then transpiration is the movement of water out of these pores on plant leaves called stomata. And when stomata open up, carbon dioxide is fixed by the plant. That's how plants eat. And that comes with an automatic loss of water because plants are near saturation in order to stay alive. So the combination of evaporation and transpiration is evapotranspiration. I study evapotranspiration, you know, at the scale of a field, even getting to the scale of a region. And I think about how plants are using water in this aspect. And Sonali is thinking of it at the regional or even the global scale and how it's a driver of climate. So we we both study evapotranspiration, or we call it ET, uh, those of us in the know. And we study the same thing, but we study in really different ways. But we had gotten together and worked on a project to just think about how irrigation changes water cycles in the Earth system. And that's how I got to know her. And so I thought it would be fun to have a conversation with her about ET irrigation and climate. So without further ado, let's talk with Sonali. Welcome, Sonali. I'm so excited to have you on Water Talk. You do such cool work and you think about this stuff like land use and irrigation and climate interactions. Can you talk a little bit about the mix of what you study and how you came to be interested in all of this stuff?

Sonali McDermid: 4:50

Yeah, for sure. It's really nice to be here too, Mallika. I've been wanting to do this for a while, so thank you. Yeah, gosh, how did I get here? That's sort of the universal question. So I started, so my doctoral work was in paleoclimate, actually. So I know I was studying a time period about three million years ago called the mid-Pliocene warm period. And long story short, a lot of what I focused on was the South Asian summer monsoon and how that may have operated differently during the mid-Pliocene warm period or just under warm climate conditions. And that got me really interested in future climate change and how changes that we might expect in the future could play out on the monsoon system. And around the time that I was finishing my doctoral degree, uh a really major project that was the first of its kind called the Agricultural Model Intercomparison and Improvement Project, or AGMET, had just started up. And we were charged with evaluating the impacts of climate change on food security across sites in Africa and South Asia. And they needed a monsoon scientist to help them downscale projections for crop modeling and eventually socioeconomic modeling results. And I knew nothing about AG, but I knew something about the monsoon. But I really wanted to get into agricultural work because I don't think I was supposed to do this. But for four years in graduate school, I also managed farmers markets around New York City. So I got to talk to a lot of farmers and made some close relationships and just was really thinking about food a lot in my personal life and in this other job that I wasn't supposed to have. And I just really wanted to figure out how to combine the two. So I started that project in 2011, 2012, and started to just eat up everything I could about agricultural modeling, agricultural system science, looking at interactions between on-farm decision making and household characteristics, and looking at how all of that intersected with climate change. And I just never really looked back. And I'm an earth system scientist, I'm a climate modeler by training. So while I was looking at all of these climate change impacts on food security, I also started wondering about well, how does management influence the way climate change is experienced on the ground? And also, how do we create our own vulnerabilities in the way that we manage things, right? And how do we maybe even offer uh avenues for resilience, right, if we were to manage things differently. So then I became very interested in the feedbacks of land management, irrigation is what I started with, to the climate system. And so while I was doing all of this agricultural modeling and linking climate change projections with ag models, I was also trying to find ways to represent agriculture and earth system models and climate models, which I'm still doing today. So that was the other half of my work. And there, you know, we've just started playing with a lot of management, looking at irrigation in particular with the model I work with, but we've also looked at soil degradation. We're interested in changes when you change out so-called natural vegetation or grasses for actual crop characteristics and the way crops grow, which are very different, right, from your native grasses. So we started crop calendar, so we started playing with a lot of that, and we found, you know, there there were some really interesting, interesting responses there. So that's sort of my evolution into this space, and it's just so addictive and interesting. And I think it just captures so much of what I love about looking at climate and land. It's just ag is just the way that we interact and express ourselves on the biosphere. So I'm sort of interested in all questions related to how we interact and manage and engage with the land service.

Mallika Nocco: 8:26

Awesome. That's super cool. I like what you just said about ag a lot. That is a great. That's a really good quote. Um That's the way I look at it. That's really neat. So you and I both study evapotranspiration as one part of this. It's kind of like where we connect, you know what I mean? And I don't know if you've noticed, but it's been in the news lately as corn sweat. Corn sweat. Yes. Well, um, I'm just as curious. And that all of a sudden was in the news everywhere. Um, you know, with the humidity in the Midwest, which I've been living. And I was just kind of curious how you feel about corn sweat or plant sweat as an analogy for ET. Are you for or against the analogy?

Sonali McDermid: 9:10

That is so interesting. I know I sort of balked a bit just instinctively at this idea of sweat, right? I I think, oh, do I have a firm position on this? I mean, it's such a scientific thing to ask, right? Like, what are you nitpicky about? And I suppose like sweat on on animal bodies or human bodies, that evaporative cooling, right, is a way to kind of regulate temperature, right? And that sort of thing. Whereas like water emitted through stomates, right? Like when you actually look at transpiration coming out of a plant, right? Or water coming out of a plant, there are different processes at play that, you know, of which cooling is one of them just because of the thermodynamic component, but like it's not necessarily that. That's that's the byproduct, right? Of what those processes are. So I don't, I don't know about how close. Like, I guess I guess what I'm saying is you can nitpick at that analogy. I appreciate ways to engage the public in thinking about evapotranspiration, right? I I think that's I'm with you on it.

Mallika Nocco: 10:23

I it's this is hilarious. I have the exact same feelings of it. Like it prickles me up a little bit because I'm like, well, it's not evaporate. The exact same reason about like the stomachs and how it's a pump and like there's this other thing.

Sonali McDermid: 10:36

But yes, exactly agree with you that if it brings more people to thinking about ET, for ET, I feel like any advertising is good advertising so long as like it starts a conversation. So I yeah, I'm I'm okay with it. Uh yeah, I probably don't I don't want to say that, you know, in many like I'd probably pick at it if I saw it in a publication anywhere, but uh, but I'm I'm okay. I'm okay with people talking about that. Yeah.

Mallika Nocco: 11:02

Okay, good, good. Yeah, I was just curious because I was like, wow, this is everywhere right now.

Sonali McDermid: 11:07

Good question.

Mallika Nocco: 11:08

Um, yeah, so kind of getting into the ET topic. Well, we, you know, we water plants and we think about using additional water as irrigation for these plants. And I guess everybody's talking about corn sweat when they're talking about this ambient change in humidity. But one of the things that you study is what happens to that ET after, you know, it has those ambient changes and how it can actually impact climate. Yeah. And I'm wondering if you could just talk a little bit about where where are the pathways.

Sonali McDermid: 11:41

Yeah, yeah. And it's so interesting, right? There are so many different pathways and they kind of intersect, and it this is where sort of it becomes complicated, right? And, you know, and I think that we've we've seen this and we talk about it within the research community, you know, that irrigation can cool things down a little bit is pretty widely known and not really in dispute. But what it does to water and the hydrologic cycling and where water goes and where it comes back is actually a much more complicated thing. So, and and I think with this corn sweat idea and just ET in general, where irrigation water, for example, is really being applied, or even where you've just got very high crop productivity, right, associated with high ET, there are increasing concerns about that that water gets evaporated into the boundary layer, into the lower atmosphere, and increases the likelihood of humid heat extremes. This is something that I think is on people's minds when they're reading about corn sweat right now and you know, when we're thinking about this. And so definitely the idea of it just hanging out and dispersing, not dispersing very widely, but impacting the communities where or adjacent communities where irrigation is being applied, I think is a really important thing to consider. But water doesn't stay put all that easily either. And so once it goes up into the atmosphere, we're interested in looking at all of these different pathways, one of which is it just fuels convection, you wind up getting a cloud layer on top, and then it maybe rains right back down again. So this is sort of this moisture cycling component where you're kind of what whatever goes up comes down, and maybe it comes down very close to the site that it went up in as transpiration. So this interplay between transpiration and rainfall by way of convection over the sites where this water is transpiring. So that's one pathway. And there's, I think, evidence of that happening across some irrigated locations. For those areas where you've got heightened productivity of crops or where you're applying a lot of irrigation, that's also subject to really strong currents in the atmosphere, you know, atmospheric circulation, right? Where you can have a lot of wind and invection of rainfall and transport of that rainfall elsewhere. That's also something we see across the Mississippi Valley, or that's been suggested by a lot of the studies we've looked at across the Mississippi Valley in other places, such as the Middle East over the Arabian Peninsula, maybe some suggestion over parts of South Asia. So the idea that this water that's being lofted into the atmosphere via ET in one location where there's a lot of cropland, but actually finding its way down someplace else, you know, that's something, that's another pathway that's of interest. And now we start to get into remote effects over areas that get really hot and are irrigated, where that heat over the Arabian Peninsula parts of South Asia, northern parts of South Asia, where certain areas, when they heat up, they drive a lot of large-scale circulation, such as the monsoon circulation. It's hard to fully prove, but we start to run modeling experiments and we try to look at the data and we see, oh, well, you know, irrigation in the way that it cools the land surface down and prevents it from getting really hot could actually impact some of these circulation systems that maybe rely on that heat, that rising air in one area. And so the idea that if you irrigate a certain place, like the northern South Asian continents with the endogenetic basin, and that suppresses a heat load that would develop, it suppresses convection within that area, and that could actually impact the monsoon is a really important dynamic that we're trying to figure out is this really happening? Because if it does, when you think about this, most of South Asia's farmers are rainfed. And so if you're impacting the monsoon system by irrigating in one small place, right, and you're impacting what the rainfall that that monsoon system brings in all these other places, now it's not just an inconvenience. There's other, you know, even social factors at play. So yeah, so it kind of crosses scales, I guess, right? It can go up and come down at the site of location, it can go up and maybe not come down for a really long time. It can go up and it can come down in someplace else. Or just the idea of irrigating and how that changes temperature can modify even large-scale circulation systems potentially. And all of those things are things that are right now up in the air.

Mallika Nocco: 16:06

Pun intended.

Sonali McDermid: 16:07

Well, kind of slightly intended. Because we just we don't have enough data, we don't know, we don't quite know how to look at these things. Our models are not all that great, but they're suggesting something. So I think there's this really interesting interplay between models and data now, too, to say, okay, the data are showing us what's actually being irrigated where, where the crops are, where the irrigation is. We can feed that into our models and try to understand that a bit better. The models might point out some weird interactions that we might say, hey, data people, can you go back and see if this is actually happening? So, anyway, so we can follow these pathways using these combined approaches that I think are getting really exciting, even if we're not there yet completely.

Mallika Nocco: 16:44

Absolutely. Something that I have been thinking a lot about related to this is the export and import of water by ET, right? So, like from my perspective, I think about it, and you know, we have all of these groundwater sustainability issues related to irrigation. And so this idea that we could take groundwater from one place, use it to irrigate a crop, that crop sweats or has ET, and then that that water gets carried away and then lands in a totally different community or place as rain. Yeah, that really kind of like blows my mind in the way I think about just water management. And I have seen some studies also that, you know, are suggesting that that's happening in the US. Like, how what how do you think we should be thinking about that? Or like, what do we need to get a better hold on those types of interactions or like this idea that there's importing and exporting of water that we might not be aware of?

Sonali McDermid: 17:51

Yeah, yeah. And it's it becomes this, it and this is where I really love the inter and or multi and or transdisciplinarity of thinking about water, right? I mean, when you think about water impacts happening across large spatial scales in terms of management, right? Imports and exports, like my mind goes to things like transboundary water issues, right? Where states, you know, whether it's within a country or across states, across countries, you know, disputes over water, who has it, who has the right to it, where it gets imported, where it gets exported. These ideas of virtual water flows are now really being tracked, right? That's the food, that's the water that's embedded in our products, their food, but also other products that we use, clothing, for example. And you can kind of map now virtual water trades as a result of water used in different products. And I think what you've highlighted here, that on the ground water management, right? I mean, all water is sort of transported from somewhere, and that we know, right? And and we know what these lifetime scales are. But the idea that we've unearthed in large form a lot of fossilized water, water that wouldn't have been on the surface on the timescales, at least, that that we're kind of unearthing it, right? And we're now deploying it, right, on the land surface. And at some level, we can't actually control where it goes and that that's not being accounted for. The idea of import and export has so much embedded in those words. It's no longer just a transport. And I think climate scientists are very they like thinking about things like fluxes and transports and advection because it scientizes it. But then you start talking about imports and exports, right? That socializes it, right? You start thinking about well, how do you regulate that? How do you govern who's responsible for that, right? Is that good or bad? Is it good for one community, but bad for another community? Do they and it's sort of creating your own vulnerabilities too, right?

Mallika Nocco: 19:42

Yeah. Right, right. So starting to think a little bit about irrigation and then global climate change, there are all these irrigation hot spots where we're we're turning up the plant sweat. And as you mentioned, we've got you know, irrigation-induced cooling happening. Uh if those places stop irrigating, like, do you think that we are gonna lose cooling, you know, in a warming planet? Like, do we have like an unsustainable air conditioner right now from irrigation in some of these regions?

Sonali McDermid: 20:20

Yeah, I actually wonder like how much, I think most air conditioning is unsustainable. Yeah, that's true. Yeah, you know, it's interesting. We did a study not long ago, a colleague of mine at GIFs and a few other folks, where we asked the question, you know, how much and for how long will irrigation serve as an adaptation option, right? Getting or as adaptation, even if it wasn't intended for that. I don't think historically most people were irrigating to mitigate heat extremes. They were irrigating because you have super productive crops, and that was part of the technology packages, right, that needed to boost production and productivity and that sort of thing. So this idea that irrigation serves this cooling, I, you know, and and and could potentially be an adaptation strategy for climate change is is a relatively recent. And so we asked the question for how long does this cooling last? And we looked at that with a climate model and we ran high emissions climate scenarios. So, you know, something along the lines of I guess worst case at the time. And we looked at the most heavily irrigated regions. And, you know, what we found is that in some regions, the cooling seems like it would be sustained until past the 2050s. But in other areas, once you hit a certain level of warming, typically under the more extreme climate change scenario cases, and you start to get closer to the end of the century, 2060s, for example, 2070s, that at some point you hit a level of warmth where irrigation can no longer guarantee that you don't experience very big heat extremes. In other words, that adaptation capacity of irrigation starts to wane. And this appeared also in several regions. And so at a certain level of warming, certainly when you start to hit like two to three degrees, we had a postdoc who also looked at this fairly recently and looked at um extreme events, not just like the warming signal, like the mean warming signal, your sort of secular trend. And again, once you start getting past the global temperature increases of two degrees C, right, and start approaching three degrees C at some level, the warming just sort of supersedes everything else. When you couple that, I think, with exactly what you just said, which is a very big concern, that most of the places where you're seeing this happen are areas of really tax groundwater or even where surface waters might not be running to the ocean anymore, it it is not necessarily a sustainable solution everywhere. The other higher level question that that introduces is what does it matter and for for who or what? There's been some recent studies that suggest that humid heat, you know, insofar as that you have irrigation there, is less detrimental to crop growth than dry heat. And even that is there's lots of nuances with like low vapor pressure deficits and crop growth, right, that that start to come into play. So, you know, I don't know how universal that is everywhere, you know, at every at every level of temperature increase. So maybe you you run into a situation where if you irrigate heavily and you're maybe not having the cooling anymore, but you're having a lot of water vapor still in the atmosphere, right? Maybe, maybe that lower vapor pressure deficit to the extent that you can manage it still, you know, to the extent that you have enough water, even if it's getting hot and you've got a humid heat extreme, maybe that doesn't impact the crop so much, but you know, it it'll have impact on laborers and anybody who's working outside, right? So there are these trade-offs. I don't see very many studies that have been looking at this similar question about what adaptation will irrigation really be able to serve? Should we even look at it that way? Like, is that even an appropriate way to look at modern irrigation and the way that we're deploying it right now? I think there's room for it to be looked at that way, depending upon where you are. I just don't think that's true everywhere. So I even kind of hesitate at the idea of thinking about irrigation writ large as an adaptation option. And it's not clear without additional work to see how long it can be an adaptation option, you know, in into the future, depending upon when we decide to start mitigating climate change.

Mallika Nocco: 24:44

Yeah, it's really interesting from my perspective and the farmers that I work with, they're not necessarily thinking about it as an adaptation to climate change when they are using it as heat mitigation. But the folks who have irrigation systems in place, when a heat wave comes, are turning them on. Yeah, and they're using it to cool stuff down. It is, I think, an important kind of ethical and philosophical question to consider should this be an adaptation and where should it be an adaptation is really, really interesting to think about.

Sonali McDermid: 25:22

For sure. The way I look at it and the places where I think it can serve maybe as adaptation is this nexus of adaptation and development, right? There are areas I'm thinking mostly across, you know, so-called, I guess, global south, across Africa, across hot climates, across South Asia, across, you know, where if you do have the resources, irrigation, it's not just about climate adaptation, but it can serve a host of purposes, including increasing productivity and therefore livelihoods and helping with higher productivity systems. And I think that's worthwhile. And I think that that's something that maybe irrigation in and of itself isn't imparting an adaptation through even through cooling, or maybe it does, but that's not really the thing. But it could, it could serve adaptation. So one scenario is that you start to deploy irrigation where it's sustainable, and maybe you do it with drip or you do it with high efficiency systems, and maybe that serves to boost income or move towards higher productivity systems that can benefit the household, and then the household can start investing in things that can help adaptation to climate change in other ways. So there are these indirect effects, I think, in where irrigation and other considerations for improved farming systems, whatever, however, those are defined for whoever can serve these indirect adaptation goals. But those places have to be very carefully considered because by laws of conservation, right? We we have what we have, we're not getting any more. It's just gonna move around quite a bit, right? So, so in order to make the decisions about where might be best to irrigate, where not, what's sustainable, we really need to start bracketing, we need to be considering future climate change in those calculations, in those assessments. And we really need to start looking at future water availability and what can happen. And there are people kind of looking at this, but it's still done in a fairly coarse way. And it really comes down to local watershed management, right? And sort of how people are thinking about water in a locality, and that can be very different from what we represent in models.

Mallika Nocco: 27:23

So yeah, I just want to circle back to something you said. It sounded like, and this makes sense to me, humid heat extremes are better for plants, but bad for humans, and arid heat extremes are better for humans, but worse for plants. And that feels like a problem or a paradox in places where you have farm workers and people who are working in these systems.

Sonali McDermid: 27:50

Yeah, I think that's right. I think at the kinds of heat extremes, even dry heat extremes that we're seeing now, I like I would hazard that even dry, like some of these heat extremes now are bad for both. But it it seems like there's some evidence to suggest that humid heat extremes that crops could bear a bit, they're not as badly hit, let's say, under humid heat extremes. But the problem is that crops don't harvest themselves, right? It it's a system, it's an agricultural system, and there are people in play. And yeah, you could mechanize and maybe have one person be able to run a combine through a field, right? And do everything and not have to worry about like, you know, all the manual labor associated with that. But that still has its own vulnerabilities, and ultimately, you know, this is a coupled natural human system, or even in some cases, a very human system when you think about what domesticated crops, what crops are in terms of their domestication processes. So I I just I think it it's important that the science is disentangling this and showing that, oh, humid heat may not be bad from crops, and that has implications, and it might be good implications from a yield perspective. But to me, that's important from a scientific perspective to disentangle. But when you start to then ask the question, okay, what do we do about this, right? What's the policy implication, or what sorts of labor laws should we have, or how do we actually think about past the farm gate, right? Like then we can't stop at thinking about how crops are going to respond. We really need to think about the system as a whole that includes the labor dimension and component. So so yeah, I I think that's right. You have these differing impacts, particularly with respect to humid heat on crops and people. But I I don't know how far that gets us in the solution space if we're not thinking about these things together. Yeah.

Mallika Nocco: 29:45

For sure, for sure. So I wanted to talk with you about models and like they're they're such a big part of you know your toolbox. And sometimes they can come under heat for like not being real, especially by people who Who have an interest in making sure that they are not to be trusted. Right. And I'm wondering if you could share some of the practices that you use to kind of keep these models in check that you're using to model some of these really complex interactions.

Sonali McDermid: 30:16

So a couple of things, right? There's like a philosophy of modeling. Models have to be fit for purpose, and that purpose has to be very clearly defined. And so you want to match the tools with the question. And when we use climate models, and I can speak mostly for myself and like hazard a guess that I can speak for my colleagues, I don't think any of us is saying this is the real world, right? Or that this is this is exactly what's going to happen. We're not making predictions about anything. What we do is we structure the models. Like a lot of what we do and a lot of how we run our models is really to understand the role of irrigation. And so, in many cases, aside from the study I mentioned to you about future climate change, we're often looking at irrigation alone, irrespective of other anthropogenic forcings, like irrespective of greenhouse gas emissions, irrespective of aerosols. We're really just interested in the role of irrigation alone, because what a model allows you to do is in some ways, even though models are getting more complex, is reduce the complexity to just understand do I understand this component of the system, right? Given what I know about how the world works, about basic physics, maybe some chemistry, does that check out in model space when I kick the model in a particular way? And if it doesn't, and I see a really different impact than what I expected, you know, a good modeler, your first instinct is that my model's wrong. Because it probably is, right? Like, and so it's not just the right question and the right tool, it's also a healthy level of skepticism for your own model. And I do think that's a really important part of model philosophy is to assume even if you get the right answer, it's for the wrong reasons and something's wrong with your model. And so instead of saying, hey, I ran this experiment, this is what I found, this is the prediction, this is right, you run an experiment, you say, this is what I found. Okay, this checks out, but now I'm gonna systematically go through my checklist to see where this could have gone wrong, so that I prove to myself that, okay, no, no, no, everything's checking out. This response seems to be physical. It seems to be, you know, an accurate representation of thermodynamics or an accurate representation of my physical system to some degree, knowing that it's never gonna be perfect, right? No model ever is. And in some ways, they're not meant to be. So now that we have this understanding that the model is not intended to replicate reality. In fact, no model ever will, right? Then we start asking, well, what are reasonable questions to be asking of this model? Our models are climate models, they're pretty coarse resolution. They're we cover one grid box is gonna cover at this point 100 kilometers. Some of the more state-of-the-art ones are 50 kilometers or 25, but this is still pretty coarse. They take a long time to run. So we're asking questions, usually on long time scales and large spatial scales. We're asking the question, not does is this particular field going to have enough water to irrigate and how much by 2027, by June 2027? That's not the question that we're suited to ask. We're asking the question of how much does irrigation matter on a regional level, on a continental level, on a global level? And can we see, if we put irrigation in the spot for a really long time, do we see some long-term impact on, for example, the secular warming trend or on cooling? Or do we see changes through the volume of water we're using globally? Do we see changes in aquifers, right? The depth average, do we see increases in sea level because of it? And that's actually something that has come up in studies too, the amount of irrigation that we're unearthing from aquifers, and then it's actually, you know, traveling through the atmosphere and most transporting. Yeah, transporting through the atmosphere, exactly. And then coming down most likely over the oceans, given the area of coverage over the oceans, right? That then it could be contributing to a tiny, tiny amount, but perceptible of sea level rise. So those are the kinds of questions that we're interested in asking. And I think where we get a lot of flack is this a failure of communication between the different scales of people who are operating and interested in irrigation, right? That's everybody from the farmer at the site, the point-based scale, all the way up to your global climate modeler. And, you know, and when you hear the word model, you really have to ask yourself, well, what do you what do you mean by model, right? Like what's the scale? What's the intentionality? What how are you using? What's the question you're asking of it? Is it empirical? Is it process-based? Like there are so many different kinds, is it AI, right? Like it there's so many different kinds of models, and we kind of all treat them all the same, but they're really function in very different ways and for very different purposes. So that's the philosophy and what I think about when I think about modeling. And I think as modelers, we do need to be very careful to ensure that we're not overstepping the bounds of what we can do with our with the tools that we have. I think in the onus onus is also on us to say, okay, what of the scale that I'm doing matters for the scale that you're operating at, right? So I don't know if that answers your question, Gregory. Well, but it does.

Mallika Nocco: 35:26

No, it's really helpful to kind of think about it that way. Um, so we're we're kind of our time's coming to an end, and we always like to ask people if there's anything else that you just want people to know about the work that you're doing and how how we can support your efforts.

Sonali McDermid: 35:43

Yeah, that's a great question. So I am really interested right now in what I was mentioning earlier, and that's this intersection between water management and the people who who are performing that water management. And, you know, I don't think anybody wants to waste water, and I don't think even most people who manage water would look at anything that they're doing as a waste of water. But I think that right now there's a lot of competing priorities between why we manage water. Do we want manage it for biodiversity? Do we manage it for food and farming and food production? Do we manage it for urban areas? Do we manage it? You know, there's so much demand on a very small amount of water when you look at our freshwater supplies globally, right? And in terms of the fraction of water that we're actually using. The part that's accessible to us is incredibly small. And so it's a very scarce resource overall. And we have all of these competing priorities for it, and all of them are becoming increasingly urgent in demand. And so I don't necessarily have an ask except to say that I definitely hope the younger generations of um or the early career folks are interested in not just in one question or just the biophysical or just the social, but can understand how the work that they do actually translates across disciplines, across spheres, across academia to practitioner communities. And not everything you do is going to be applicable to all, right? Again, you know, the right question for the right tool. But I do think it's important to be cognizant that the way that I represent irrigation in my model is not the way that it's done in real life, right? And to have that understanding and to at least be humble enough to admit that like there are interactions here that scan beyond the questions that we're asking, I think that's a really important first step towards just managing things in a much more responsible way, whatever that means, and just an appreciation that that can mean very different things. So I think what I would want to see is just more people from different communities talking to each other to think through these issues in a way that, you know, foregrounds really a sense of values at the end of the day.

Mallika Nocco: 37:53

Wonderful. Well, I love that remark and that sentiment. So thank you so much for that. And thank you so much for being on the show. I really appreciate your time and your expertise.

Faith Kearns: 38:05

Thank you for listening to the Water Talk podcast. I'm Faith Kearns and I'm the Director of Research Communications with the Arizona Water Innovation Initiative at Arizona State University.

Sam Sandoval: 38:15

My name is Samuel Sandoval. I'm a professor at UC Davies and a cooperative extension specialist in water resources management at the University of California Division of Agriculture and Natural Resources.

Mallika Nocco: 38:26

I'm Mallika Nocco, assistant professor and state extension specialist in agricultural water management at the University of Wisconsin Madison. If you enjoy our show, please review, listen, like, and subscribe anywhere you get your podcasts. Please find transcripts and additional content watertalkpodcast.com. Original music by Paloma Herrera Thomas.