 Good evening and welcome to the Longmont Museum, a center for culture in northern Colorado where people of all ages explore history, experience art, and discover new ideas to dynamic programs, exhibitions, and events. For real. My name is Justin Veach. I'm the manager of the Stuart Auditorium, and I curate public programs for the museum. Tonight's program is part of our Thursday nights at the museum series. We titled it that because it happens every Thursday night at the museum. And every Thursday night, we offer you a little special something, whether it's a talk between two amazing scientists, a film from the Bullard International Film Festival, a performance, poetry reading, you name it. It's a veritable potpourri of cultural delight is how I like to think of it. I'd like to thank all the folks who make these programs possible. The Scientific and Cultural Facilities District, the Stuart Family Foundation, the Friends of the Longmont Museum, our many museum donors, and our museum members. I kind of think I see some museum members out there tonight. Do I? Any museum members with us? Hey, thank you. We simply can't do all that we do without you, so thanks. Tonight's program is part of a collaboration, an ongoing collaboration with the National Center for Atmospheric Research, otherwise known as NCAR, and their Explorer series. The Earth system is interconnected, and the water cycle is one important connection that scientists study. A change in climate can affect precipitation patterns, which in turn can impact agriculture and society. But did you know that how we manage our land also has dramatic impacts on our climate system? In this Explorer series conversation, discover the connections between plants, the water cycle, and our change in climate, and opportunities to get involved. With us this evening leading this conversation is Dr. Danica Lombardazzi. She's a project scientist in the Climate and Global Dynamics Laboratory at NCAR. She is a global change ecologist and co-founder of Boulder's Ozone Gardens, which includes the garden at NCAR's Mesa Lab main entrance, if you've ever been up there. Lombardazzi's work uses a combination of ecological observations and global scale models to investigate how terrestrial ecosystems are changing in response to human activities. As a scientist at NCAR, Lombardazzi works on improving the ecological processes represented in computational Earth system models and understanding the uncertainty in simulated carbon cycle projections. Did you get all that? She also studies how to best manage our ecosystems to maintain food and fiber availability in the future while minimizing the contributions to climate change. She received her Bachelor of Science in Environmental Science with a minor in music, of course, at Colorado College and her PhD from Cornell in Ecology and Evolutionary Biology. She is a founder of the Ozone Pollution Education Network and leads the Citizen Science Data Collection at Ozone Bioindicator Gardens within this network. Joining her this evening is Dr. Adriana Bailey, an atmospheric scientist in the Earth Observing Laboratory. She works at the NCAR Research Aviation Facility as well. Her research focuses on understanding the processes that control humidity, cloudiness, and precipitation. She also studies how variations in the Earth's climate affect moisture transport, how efficiently clouds form precipitation, and how moisture mixes between different layers of our atmosphere. As part of the RAF, Bailey supports measurements of water isotope ratios and airborne measurements of winds and turbulence. Her water isotope instrument is requestable as part of the National Science Foundation's lower atmosphere observing facilities. Prior to becoming an atmospheric scientist, she worked as a science news writer for the University of Colorado and NOAA's Cooperative Institute for Research in Environmental Sciences. She credits writing about science which requires asking lots and lots of questions for stoking her interest in scientific inquiry and for giving her the confidence to embrace what she doesn't understand. Bailey is also working to inspire young girls to pursue careers in STEM as an if-then ambassador with the American Association for the Advancement of Science. Through this ambassadorship, her work was recently featured on the CBS television show Mission Unstoppable. Ladies and gentlemen, please welcome Dr. Danica Lombardazzi and Dr. Adriana Bailey to the Longmont Museum. Let's make sure we've got this on. Thank you so much. That was more than a mouthful for an introduction. Thank you, Justin. But what I really appreciated was the way that Justin sort of described this particular presentation tonight. Right? When I read a title like this one and see a photo like the one that's up there, I have a very particular mental image in mind and maybe you do too. For me, that image goes something like, if we expect climate to change, we're going to expect changes to our water cycle, changes to precipitation patterns. And those changing precipitation patterns are likely to affect plants, how well they grow, and also crops, our agricultural output. But that's actually not the story we're going to be telling tonight. Tonight, what we're going to be thinking about is how is it that plants, including crops and agriculture, how do they influence the water cycle and change patterns of precipitation that then have these longer-term impacts on our climate system? And so I want to be really clear about one thing. If we think about a changing climate, certainly one of the biggest drivers in that changing climate system is the burning of fossil fuels and the emission of greenhouse gases. And that's causing global temperatures to increase. As we can see in this plot from NOAA, we're looking at temperatures increasing over the 20th century. Those increases in temperature, we expect to have implications for the water cycle, changing patterns of rain, changing flooding, changing drought. So that's certainly one of the biggest contributors to our current climate change. But that doesn't mean that changes to our land cover and changes to the land surface can't also have a meaningful impact. And in fact, that's what we'll be focusing on tonight. So at the National Center for Atmospheric Research, we're interested in these kinds of connections between the land surface and the atmosphere, between what we call different components of the earth system, because these different components end up influencing the atmospheric phenomena that make up our weather and climate. And so if we want to be able to model and predict changes in weather and climate accurately, we really want to be able to understand and represent these earth system connections in our models and our simulations. So tonight you're going to be hearing about these connections between the land surface and the atmosphere from two pretty different perspectives. As an observationalist working in the Earth Observatory in NCAR, you're going to be hearing from me about how we can use observations to tell us about how moisture from the land ends up making its way into the atmosphere and influencing the water cycle. I guess, oh, there we go. You'll also hear from me. My name is Danica Lombardazzi, and you'll hear from me about my work looking at how plants influence climate using global scale models. So in today's talk, we're going to address four questions. The first is how does water connect plants in the atmosphere? The second is do plants cause their own rain? The third question is can agriculture change water in the atmosphere? And last, we'll look at does plant health matter? So let's dive in to the first question. How does water connect plants in the atmosphere? And perhaps this is familiar to you, but plants need water in order to grow. And water comes in different forms. It comes in rain. It comes in fog. It comes in irrigation water. But the fact is that all plants need water to grow. And so when we add this water, where does it go? What do you think? There are five options up here. It can go to the soil. It can go to the plant, to the air. It can go to all of those things, or none of those things. Oh, great. I think I'm hearing a lot of great answers. The answer is D. It goes, it's all of them. Let's walk through this actually. So plants get water from the soil. So there's water in the soil. And plants take that water. It travels through the roots and the stem and into the leaves of the plants. Once it's in the leaves of the plants, it evaporates from these pores on the bottom surface of leaves called stomata. And this process of plants taking water from the soil and having that evaporate through the stomata on the bottoms of the plant leaves is the process called transpiration. So transpiration is a biologically, the biological movement of water from the soil to the atmosphere through the plants. So when that water evaporates from the plants, it's in the atmosphere. And that water in the atmosphere, that transpired water, can condense to form clouds, which eventually can form rain. So that leads us to the question, can plants get this water back? Do you think they can? I don't know. Let's ask Adriana, because I think that she can tell us plants get water back. Yeah. So if we want to know if plants can get this water back, it's really going to lead us to the question, can plants create their own rain? So to answer this question, I'm going to take us on a little trip to the Amazon. And there are a couple of reasons for that. The Amazon is a place that has lots of plants. It also has lots of water. But it's also a place where we are removing trees in order to make room for other human activities, like agriculture. As you can see in the photo on the right from Reuters. And so it's the kind of place where changes to plants and changes to transpiration, how much water they're putting to the air, is a really relevant question for the water cycle and for climate. So keep in mind that map that you saw of the Amazon, because we're about to look at it now from a very different perspective. We're going to look at it from the lens of this satellite instrument that NASA runs, known as the tropospheric emission spectrometer, or TESS. And TESS flies on the Aura satellite. When TESS looks down at the Amazon, what it sees is this. What we're seeing are two snapshots of the Amazon in time. On the top you're looking at the late dry season. It's a transitional period into the wet season when the rains really commenced. And on the bottom what you're looking at then is the wet season when rain occurs. The shading here, the blue shading is indicating how much moisture is in the air. So that's the image that TESS is giving us. How much water is in the air. And this is water vapor. So it's not necessarily water you can see, but it's the humidity that you can feel on your skin. Let's now see another view that TESS has. Here, TESS is showing us what type of moisture is in the air. And if you looked at that left-hand column and said, well, okay, maybe in the wet season it's a little bluer. But it doesn't seem like there's a huge difference between the two. In contrast, when we ask what type of moisture is in the air, we start to see a big difference between these two seasons. With this much greener shading in the top, the late dry season, disappearing then later as the rains begin. So what do we mean by different types of moisture in the air? To answer that question, I have to tell you about flavors of water in the atmosphere. And probably from high school chemistry, you're remembering your chemical formula for water. Anyone? H2O, excellent. When you think of H2O, I think of H216O. That is the molecule you see in the top here. It's, you might call it normal water. I also call it isotopically light water. It has an atomic mass of 18. Or a total mass of 18, I should say. In contrast, there are other types of water molecules that have isotopically heavy oxygen or isotopically heavy hydrogen. And those are shown on the bottom. I've actually highlighted the HDO here, which has the heavy hydrogen because it's what tests can detect. All right. So why are we doing this whole chemistry lesson about water? The reason has to do with the way these molecules behave when you begin to move water around and in particular to evaporate it, say from an ocean surface, a river, a puddle on the soil. When you do that, the lighter molecules are quicker to evaporate, they're more efficient, whereas the heavier ones are not. So here's your pop quiz on water isotopes. If evaporation is occurring, which type of the molecules do you expect to concentrate in the atmosphere? All right. The isotopically light water molecule. And the next slide will show us, again, will give us more of a visual demonstration. When you have evaporation, again for something like the ocean or even from the land surface, that evaporation will favor the light water. All right. We were talking about transpiration before. So why are we focusing here on evaporation? This is really the key message. When plants move water into the atmosphere through transpiration, they don't discriminate between the water molecules. And so they put a lot more of the heavy HDO into the air compared to an evaporation process. So now if we go back to what Tess is showing us about the Amazon basin, we can now be more careful. Instead of talking about the type of water in the air, we can realize that Tess is showing us how isotopically heavy the water in the air is. So if we had just the information about humidity on the left, we really wouldn't be able to say where the moisture is coming from over the Amazon. But now when we add the column on the right, which tells us how isotopically heavy the moisture is, we can see that at the end of the dry season, the plants are actually pumping a lot of water through transpiration into the air, preconditioning that atmosphere for convection, which then sustains precipitation into the wet season. So the take home message is that the trees themselves are triggering their own rain. They're triggering their own wet season. One of the things that we're trying to figure out now, this is work that I'm doing with colleagues at Department of Energy and also NASA JPL, is we're trying to understand whether there are certain places in the Amazon where this transpired water through plants matters more for the water cycle and matters more for precipitation. This is a view of the Amazon from a slightly different instrument. It's a sister instrument called airs. And this isotopic information here has been color coded to show you where locally transpired water matters more. So in this case, in the wet season, we're seeing a lot of these blues and purples which are on the far left side of our color bar. That means that we're not seeing a lot of locally transpired water. The Amazon is depending on remote water from the ocean to get its rain. However, when we look at the dry season, we have a very different picture. In this case, we're seeing locally transpired water matters a lot for the water cycle and for precipitation, particularly in the southern parts of the Amazon basin. And I'm curious whether this area for anyone resonates as a geographically significant area. Was there a hand? Go ahead. And quite a bit of Brazil in the box itself. Yes, yes. So you've named a few of them. Yes, those are some of the western countries of South America that certainly have those redder colors. Going back to the box where we see locally transpired water mattering for the Amazon, this is actually an area called the Ark of Deforestation. And it's called that because it's a place where we're cutting down more trees than in other places to make room for human activities like agriculture. And I know this isn't exactly a colorblind friendly map from this is from a NASA modus, which is another satellite instrument. But the red area, what's called the forested area, this is the area mostly with trees. And the green to the southeast, these are grasses and shrublands, a more abacious cover. And you can tell this Ark of Deforestation by these green patches that are entering into the forested area. So in essence, we're actually doing a lot of the cutting of trees precisely in the places where the water from trees is important for the water cycle. So this leads us to ask one more question, which is what happens if we continue in the current patterns of deforestation that that we're currently experiencing? And at least one projection from a fairly simple, more idealized model that was published in nature is that we're likely to see fairly significant decreases in rainfall. So here on the left, you see projections of rainfall decreasing as a percentage during the wet season. And then on the right, you're seeing those projected decreases during the dry season. And what's really impressive, you'll notice that the axes, the color bar actually changes. In the wet season, some of those deep reds or browns indicate a 20% reduction in rainfall. In the dry season, up to 40%. And notice again that this is along that southern part of the Amazon basin, where we're currently doing most of the deforestation. So you know, I love to give this example of the Amazon because it's a place where there's lots of trees and it's easy to detect the transpiration signal. But it only gives us really one picture of what happens when you change land cover or land type and how that affects the water cycle. Yeah, that's right. The impacts on changes in the landscape on the water cycle really varies by region. And so if you take a look at this picture of Palisade, Colorado, what you see is this lush green landscape in the foreground. And then you can see those drier cliffs in the background. And in this particular region, it's a really, really dry region. So we don't have a lot of trees that grow naturally in this region. And then what we've done here in Palisade is we've added agriculture. And so for plants to grow here, we have to water them quite a bit. And so that watering or changing of the landscape can have large impacts. And so this is where I want to shift into thinking about, can agriculture change water in the atmosphere? And so we just heard about how trees can trigger their own wet season. I imagine that agriculture probably does change water in the atmosphere. But to start, I want to go back to this, this sort of slide thinking about evaporation and transpiration. And so Adriana just talked a lot about how isotopes and isotopic observations can help us partition between evaporation and transpiration that gives us an understanding of the biological component of those changes in the water cycle. But what I want to highlight here is that both types of moisture from evaporation and from transpiration end up in the atmosphere. And so often we lump them together into a term called evapotranspiration, which is the combination of evaporation and transpiration. And this is really a measure of net water loss from an ecosystem to the atmosphere. So keep that in mind that the atmosphere is seeing both evaporation and transpiration. So agriculture management, let's go back to that, it changes the terrestrial landscape. But we do a lot of different types of agricultural management and I've highlighted three key aspects. One is irrigation, another is fertilization, and another is agricultural expansion. So do these management practices increase or decrease water flexes to the atmosphere? Do they increase or decrease evapotranspiration? Anybody have thoughts? Which one of these might increase evapotranspiration? Irrigation, maybe so because we're adding extra water, right? Does anybody think that any of these will decrease evapotranspiration? Yeah, it's all of those things or possibilities. So I'm just going to highlight that we can experiment and ask these questions using this tool of a virtual earth. And a virtual earth is when we take mathematical equations and what we know about the earth and translate that into mathematical equations that we can then run on supercomputers to better understand what is happening to our earth. And this allows us to do experiments without actually changing the earth. And so that gives us a better indication of how processes might be changing. And sure, models are not perfect. They don't have all the right answers, they're missing processes, but they are a really, really useful tool in understanding what is happening on our planet, both from a historical perspective and a future perspective, what might happen in the future. Okay, yeah. Is that okay with you? Okay. Yep. It's extra loud. Yeah, sorry. I know some people have small children at home and so want to be extra careful. So this virtual earth is really important or a really useful tool to be able to answer and address some of these questions. So what I'm going to show here are results from a virtual earth simulation. And this is a change in annual average of vapo transpiration. And so we'll look at what happens when we turn off irrigation, if we stop irrigating all of the crops, if we stop fertilizing all of the crops, and what happens if we didn't have that agricultural expansion over the past 150 years. And I just want to highlight again that the virtual earth tool is a really useful tool because if we stopped irrigating all of our crops, we wouldn't have nearly as much food. So we can't do this experiment globally very easily without drastic consequences. So that's why we use models to try and understand what the impacts are. So let's start by looking at irrigation and your predictions were right according to this virtual earth experiment. When we add irrigated water to the land surface to grow those crops, we are increasing evapotranspiration in a lot of regions, a lot of crop regions globally. If we think about fertilization, fertilization doesn't really have much of an impact on evapotranspiration. It does change crop growth, it's really important for that. But from an evapotranspiration perspective, it doesn't really have a large impact. And I want to end with this, I just want to highlight I guess this last figure, Copland expansion. And so this includes the effects of irrigation and fertilization. So that's one important thing to keep in mind. But the thing that stands out to me here most is that it depends on where you are, what the impact of Copland expansion is. So if you are in the, let's see if this pointer works, it does kind of. If you're in this region of the U.S., for example, this eastern region, a lot of Copland, a lot of the region that, or a lot of the reason that we're seeing decreases in evapotranspiration is because in that region we've had to cut down a lot of trees to plant crops. But in the western U.S., those Coplands are more replacing grasslands. And also, it's a drier region that needs more irrigation. So we're adding that irrigation. And so you're getting both of those impacts on evapotranspiration. And so the other thing to take note of is that if you look at the irrigation plot on the bottom and the Copland expansion plot on the, or sorry, the irrigation plot's on the top, and the Copland expansion plot is on the bottom. And if you look at the difference between those two, you'll notice that many of the regions that stand out as an increase in evapotranspiration, those are the same regions where we have a large impact from irrigation. Okay. So now that we know that crops are changing the amount of water that's going back to the atmosphere, I wanted to know, can agriculture change clouds? And so to do this, we again need to use this virtual earth tool to better understand what's happening to clouds from Coplands. And so I'm going to use that to run two different experiments. One is where in all cropped regions of the world, crops are managed, they're irrigated, they're fertilized, they're planted, they're harvested. And then another virtual planet experiment is in all of those crop regions that we have today, let's plant grasses and see what happens. So grasses are similar to crops in terms of their height, but they're not irrigated, they're not fertilized, they're not planted or harvested, they just happen to be growing in those same regions. So we are not changing the distribution of crops in this virtual experiment, we're just changing the types of plants that are growing in Coplands. They're either managed crops or they're natural grasslands. So what do you think happens to clouds? Let's start with transpiration. So what we can see here, remember the transpiration is that biological pump from the roots of the plants back into the atmosphere through the leaves and back into the atmosphere. And what this figure is showing is that all of those blue-green colors are where crops increase transpiration compared to grasses. And all of the deep, all of the brown colors are where crops decrease transpiration. And I want to highlight this, this crop belt right here, this crop region in the U.S. And what you notice is that there is an increase in transpiration in crops compared to, compared to grasslands. And that's in part because crops are more productive and so they're using more water during that growing season, during the growing season. So if we are increasing transpiration, what do you think happens to clouds? Yeah, I'm seeing a lot of thumbs up. And you're right, because that water goes back to the atmosphere, we have more water going to the atmosphere, so there's more water to form some clouds. And so crops increase cloud cover through that increase in transpiration. And so I just want to come back to this photo and illustrate that crops, by changing the amount of water that's going into the atmosphere, do have an impact on clouds. They can change cloud formation. Adriana, you told us about how clouds change rain and also that they're important for climate. Can you tell us a little bit more? Yeah, I love this photo. This is actually Donica's photo. And of course it's showing these cloud changes over these crop lands. And we have talked about the way that you change cloud or humidity patterns, you can end up changing precipitation. But in this case, what I love about this photo is it shows us one other thing. These clouds are actually shading the surface of the planet. And so as a result, they actually have a temperature effect on our climate system as well. You know, this is actually a good time too, to bring up this notion of the difference between weather and climate. Because we've kind of been tossing some ideas out there like plant transpiration can change clouds and rain, but clouds and rain happen over a matter of hours maybe. These are weather scale phenomena. So how do we know then that there's this impact on climate? Yeah, that's a great question. And climate is different from weather in that it's changes in longer term patterns. And so once we're changing those longer term patterns in clouds and precipitation, that's giving us a change in climate. The thing is, is changes in the land surface, those persist for a long period of time. When we cut down forests and plant them into croplands, that's having a long term change. Trees don't grow back as, you know, they don't grow back that quickly. And so these changes in land use can impact climate through these persistent changes in weather patterns. And this, this is where the models that you work with, I think, actually are so important to this question. You know, observations, oftentimes we have shorter records or we might get a snapshot by playing, flying our research aircraft through the air and taking measurements. We don't get the same long term view that you can necessarily or potentially get by running these simulations over decades or hundreds of years to say, okay, we've changed land cover and then what impact does it have on the patterns of cloudiness and precipitation? Yeah, very true. You know, there's one other thing that's interesting about that picture. And sometimes I think it's a little deceptive is that it sort of suggests that a lot of the changes we see in cloudiness or precipitation are actually happening right over the places where we're changing the land cover or land management. And it's good to bring back the two maps that you showed previously because I want to highlight something here that, you know, Donica didn't necessarily stress, but it's also important to take away the places where transpiration are occurring are not necessarily the places where we see changes in the water cycle in cloudiness. And you can see that by this highlighted region, the black box here, it's not a region with a lot of change in transpiration, but it is a region with a lot of change in cloud as a result of those changes in transpiration. So what this tells us is that when you change the water cycle in one place, it can really have significant impacts downstream. And the reason for that is that water is very good at connecting climatically different places across the globe. We have an image of this, it's actually from another NASA simulation, which shows us really in this very visual way how water connects places on the earth. These are clouds swirling across the planet, but those clouds are moisture, right? And so if you look at a place like the Amazon in South America, you can start to see those plumes of cloudiness reaching other places, sometimes as far as the mid-latitudes. Now turn your attention to North America. Here we can see cloud swirls making their way across the Atlantic and even up north into the polar regions. So again, when we change the water cycle in one place, it's one way that you can have a very significant impact on climates in other regions. Yeah, so what we've learned so far is that plants connect or the water cycle connects plants and the atmosphere. Plants can cause their own rain. Agriculture can change water in the atmosphere, which can change clouds. So plants have this really important impact, but what about plant health? Does that actually, does plant health matter? So what human activities change plant health? Can you think of any? Yeah, fertilization. I heard herbicides. Aeropilution. Somebody is giving me a clue. And yep, yeah, insects, especially invasive insects. Yep, all of those things. Yeah, so somebody said air pollution and I want to come back to that because that is a topic that is interesting to me. And I just want to highlight, we had some pretty bad air pollution here this summer, right in the front range due to wildfires. We actually have pretty bad air pollution most years even when we don't have wildfires. And this picture of this leaf is a picture of damage from air pollution. And specifically this is damage from ground level ozone, which is something that the front range of Colorado has in high concentrations, unfortunately. So ozone might be confusing. It's three oxygen molecules and it has different functions in different layers of our atmosphere. So the ozone layer is where most people have heard about ozone. And that's a layer of the atmosphere that is actually beneficial to us because it protects the earth's surface from sun's harmful UV rays from hitting the surface. But the same exact chemical, when it's in the air that we breathe at the ground level, is toxic to us. And so it has different functions in different parts of the atmosphere. In the ozone layer, it's beneficial because it blocks sun's harmful UV radiation. And in the air that we breathe, it's toxic to us and it's also toxic to plants and it causes the type of damage that I just showed you. How do we know what type of damage ozone causes? We do this through experiments. So this is a picture of one of my experimental setups where I took chambers and I planted plants inside the chambers and I blew high levels of ozone pollution at half of the plants or half of the chambers. It was half of the plants as well. And then the other half of the chambers, there was no additional air pollution. And so what you can see is the damage that this causes is visible in some cases. So this is a tulip poplar leaf and that's the type of plant that I was growing inside these chambers. And you can see all the spots on the top surface of the leaf. And that is characteristic evidence of ozone pollution and the damage that ozone pollution causes. The picture that I showed you earlier, that's just from ambient air in Boulder. That's from my ozone bio indicator garden at NCAR. So you can see that the concentrations in the air that we're breathing here and just the air that we're breathing are high enough to cause that level of damage on the leaves. So I just want to highlight that what we're talking about here though is what's happening. How does plant health affect the water cycle? So what do you think if a plant starts to look like this, what do you think is happening to the amount of water that's going back to the air? I'm seeing some down thumbs. Yeah, it decreases. And so what I did is I took data from my experiment and also from a lot of other experiments that a lot of other people ran and I turned those data into algorithms that could tell us how the plant function changed. And I put those into the virtual earth, those algorithms. And what I found is that ozone, ground level ozone pollution does in fact decrease transpiration. And so all of the colors that you see here are decreases, percent change, percent decreases in plant water loss back to the atmosphere. And so you can see that the changes are getting up to 15%, 20% in some regions. But I really want to emphasize that the significance of this is because it reduces that evaporative cooling. So if you're not getting that evaporative cooling effect of the plant transpiration and also less water is being transferred to the atmosphere. And so if we have less transpired water going back to the atmosphere, what do you think happens to the clouds? I'm seeing more and more down thumbs. Yeah, so this is all connected. So just changes in transpiration from that plant damage is decreasing clouds. And so this figure is a little bit confusing. So let me talk you through it. This is the change due to ozone. And so there's a black dotted line. And anything to the left of that black dotted line is a decrease in clouds due to ozone. Anything above that line is an increase. And then on the, on this sort of vertical axis is that's the change in height in the atmosphere. So the earth's surface is at the bottom. What I want to point out is the growing season. So this is for Northern Hemisphere. The growing season here is June, July, August. That's when we see these beautiful green leaves growing on the plants. And that's this, this greenish colored line. So what you can see is that there are large decreases in clouds near earth surface in the Northern Hemisphere in June, July and August due to, this is, this is, you know, due to changes in transpiration from air pollution. So just that air pollution can decrease clouds in the growing season. The next thing that I want to point out is what you know what I was talking about earlier. Clouds can shade the earth's surface. They, the condensation to, to, from water to go from gas phase to liquid phase, that releases latent energy. So that causes evaporative cooling. And in addition, the clouds can block sun's, sun's light from hitting the earth's surface. And so if you have less sunlight hitting the earth's surface, you might have lower temperatures. It's usually cooler when it's cloudy out, right? Then, then when it's sunny. And that's in fact what we see. So again, look at this green line for June, July, August. And we're seeing an increase in summertime temperature. And so this is, this is just a little bit less than about a degree, one degree Fahrenheit increase in summer temperature due to air pollution cause, the change that air pollution is causing to plants. So plant health also really matters. And things like air pollution can really affect these processes. So I just want to go back to this, to this slide, to this photo and just really emphasize that plants, you know, when they, when processes change either from air pollution or climate or land use, when we're changing where plants are growing, what types of plants are growing, how we're managing that growth, not as changing the amount of water that goes back to the atmosphere. That can change things like precipitation, clouds, and it also can affect earth's temperature. So all of these pieces are connected. And it's really, it emphasizes just how interconnected the whole climate system is as a whole, right? Because then you also showed how air pollution in the atmosphere can then have these repercussions for plants, which then goes back and again affects the water cycle. Yeah, everything, everything is connected. And it's, it's what we call feedbacks when something, you know, for example, from the air, like the air pollution affects the plants, and then that, that change in plants affects the air again. It's, it's a feedback loop. So I just want to go back to, to our four questions, because we've answered these four questions now, or we've, we've answered parts of these questions. And so let's, let's just go through what we've learned. So the first question is how does water connect plants and the atmosphere? And what we learned is that plants pump water from the ground back to the atmosphere. And so that, that is all connected. And that's the, that's sort of the underlying knowledge for all of the science that we then presented in this talk. Second is do plants cause their own rain? And Adriana told us, she showed us that isotopic observations can tell us that plants generate their own water and they can, it can trigger their own wet season in the tropics. Third is can agriculture change water in the atmosphere? And I, I showed you that virtual earth simulations show that agricultural management changes the vapo transpiration and it changes clouds. So really it does have that impact on the atmosphere. And then last, what I just highlighted, this does plant health matter? The answer is yes. Air pollution damages plant health, it changes transpiration, it can change clouds, and it can change temperatures. And so really we'll just end here again with the thought that all of these processes are interconnected. When we change the land surface, we might not think that cutting down a tree might have an effect on the water cycle, but really it does. And I hope that what, what we've helped to explain today is just how interconnected all of these pieces are. And they have large, large impacts on both weather and climate. So on short term and long term time scales. So thank you for your attention and we are happy to take any questions you might have. Just a reminder, please do wait for the microphone to get to you. We are live streaming tonight. If the ozone belongs in an upper range of the atmosphere, what's it doing down on the ground and how does it get there? Well that's a great question and I will try to give a shorter answer, but I'm happy to follow up with you if you would like. Ozone and the air we breathe, there are some natural sources, but it's, the concentrations are really low naturally. And so what happens is that humans have increased the emissions of pollutants in the atmosphere. And so there are two compounds that react in the presence of sunlight to form ozone and those are nitrogen oxides and volatile organic compounds. And so both of those, both of those classes of chemicals react in the presence of sunlight to form ground level ozone. So nitrogen oxides are things like emissions from cars, emissions from power plants. Volatile organic compounds are, they also can come from cars and power plants, but they're things like the smell of gasoline is a volatile organic compound. They also come from trees, you know, so there are natural sources of both of these things. But humans have really dramatically increased the concentrations that are in our atmosphere. In the front range of Colorado, cars are a big source and also methane is a volatile organic compound. And you might remember that methane is effectively its natural gas. And so the natural gas packing that we're doing when it's, when that, when there are leaks from the natural gas mining, that can actually also contribute to ground level ozone formation. And I should emphasize again that this is what we call a secondary compound. So it's formed in the air. So it's not, again, you know, Adriana told us about transport of water. It's the same thing for air pollution. Air pollution is transported. And so when these emissions go into the atmosphere, they're transported in the ozone forms, usually downwind of the source. So you showed us that the deuterium or the heavy water is concentrated, at least more by transpiration than evaporation. You're not, haven't mentioned anything about the 71% of the oceans. What partition are you seeing in evaporated water from the oceans? And also what is the impact on that water in the air if it is the heavy water as opposed to light water? Okay, hopefully I understand your question. If not, please ask a follow-up. But so when you evaporate moisture, whether it's from a land surface or from the ocean surface, you will preferentially move more of the lighter water into the air. So of course, just in this very general sense, there is more light water than any other type of water. The rest are very, very tiny, tiny little bits. But you can change that relative concentration. And that's what we end up looking for is the ratio of the heavier molecule to the lighter molecule. So again, over if you're evaporating from an ocean surface or the land surface, you tend to put more of the light water, you move the more efficiently into the atmosphere. As far as what happens then downstream, this is where it becomes a really nice tool for sort of fingerprinting where moisture came from. Because every time you then condense water and make a cloud or rain it out, you preferentially get rid of the heavier water. So the atmosphere becomes lighter and lighter, the farther down the water cycle you travel. So we use that fingerprint then to say where through the water cycle this moisture has come from. And oftentimes we can get close about the general region it has come from as well. Did I get some of your question with that? So going specifically to Colorado with our fires that we've had the last couple years and the pine bark beetle, we have substantially decreased our transportation. So we are in essence creating more drought situations for us by these two situations. Yeah, that is very likely the case. And it's not maybe that's something that we could measure with isotopes actually. But I don't know of any, I haven't specifically looked at that, but that it's a great thought because it is very likely true and that's a hypothesis that we could test. The question was with fires and with bark beetles in Colorado we've significantly reduced plant growth and therefore plant transpiration. So did we make ourselves a drier environment contributing to a drier environment? Really appreciate you guys taking the time to tell us all of this. I have one comment followed by a question. This is very contrary to everything I've ever heard about manifest destiny and does rain follow the plow? So I really appreciate this interesting take. And then I'm sure this is a question and probably doesn't have enough data long term to really warrant an answer, but over the years and centuries we've put a lot of trees and other things out here in Boulder and the rest of the United States trying to make it look more like the east. Do you have any data that shows how long term tree growth has maybe impacted these sort of cycles or you just have information on like theoretical grasslands that we can put in place of these current crops? I could start a little bit and then Donica can correct me because I feel like this is probably more her area of expertise. One of the challenges we run into right is that we're still developing a lot of these tools to study these questions. And so Donica specifically showed simulations that come from these global models which up until very recently had a pretty pixelated view of a small place like Boulder. Like for example, Boulder, Longmont would not be resolved in a climate simulation. So answering some of those questions like if we add a lot of trees to a particular urban area those are questions that we've had to start developing new tools to even be able to answer. And I think we're getting close. Like we're getting to places where we're resolving clouds and convection like storms, individual storms. So I think we're getting really close to be able to answer those with more accuracy. Yeah that is a great point and it's very true that we're getting better at trying to understand this but there's still a lot that we don't know and understand and it can be really hard to attribute specific processes. And it's part of the reason why we use these models is because it's easier to turn on off. Sure. Yeah so the you know I think that that's that's a it's a great point and we have studied so for example when European settlers landed on the eastern US they deforested a lot of that area. And then since then there's actually been a lot of reforestation so regrowth of those forests. We have seen that there are changes in precipitation and in the water cycle in those regions. I haven't looked specifically at Boulder you know one of the problems with planting trees in dry places. You know I've seen somebody talk for example about the million tree initiative in LA is that there's not always water to help those trees to grow. And so we have to be careful in thinking about where we are planting trees and and how we're you know going about doing that and a lot of people want to plant trees to help climate change but it's it's not always just an easy answer easy solution so we need to be thoughtful about those kinds of things. Microphone sir. I was thinking about the Central Valley of California and down into the Imperial Valley and so in the last 20 years the rainfall in the mountain or the snow mountain mountains is decreasing so that you have less water coming into the Central Valley and this urban areas are buying up all the farmland for the water rights and the water's going away. So you have effectively a drying of a massive agriculture area that's happening now granted. 50 years 70 years ago it was all desert to begin with but that's a different discussion. So how does when you when you look or try to can you use an area like that or model an area like that and see what what is effectively a really rapid drying of a massive agricultural area has on climate or have you looked at that or can you talk about what you would expect to happen given all your models? Yeah I can so I haven't looked specifically at that myself in part because the the agriculture portion of the model that we use is pretty new and so it's it's actually a really exciting new feature of the model um and so so yeah I haven't looked at that part or that region specifically because most of the simulations that I've been running so far have been global in scale and and not really regionally focused but I think you're you know you're right we have added agriculture to the Central Valley which was really dry we've pumped a bunch of water there and so that has you know that had this impact of likely increasing transpiration increasing um you know we that that local evaporative cooling but sometimes that moisture gets transported away like we were talking about earlier and so as you're drying down you know you're running out of water in some in some capacities there's less water in the aquifers there's less water in the surface water and streams that we're using for the irrigation there and so that can have an impact on um the evapotranspiration as well and you I imagine that you likely could see a fingerprint of that in some of the weather patterns that we're seeing in and potentially the climate system as well. I had a question about the virtual earth models and you've talked about the increasing resolution of these models and I'm curious about what are the primary constraints that these models and increasing their resolution increasing their fidelity or whatever other attributes you're trying to improve what are the constraints on them there are they primarily computational or are they algorithmic as well? Yeah I would say a little bit of both but there there is a huge computational cost and um and that's that's hard to overcome but we are our our computers are getting faster and faster bigger and better um with newer technology and I think I don't I haven't been in the Mesa Lab to go downstairs and visit their um their super computing center but they had I remember from a few years ago they had a display up that said your iPhone 4 or whatever generation it was is faster than our original supercomputer which was state-of-the-art at the time and so we are increasing computing capabilities and so that is allowing us to do some of these higher resolution model simulations so that is a good thing but there are some algorithmic um components to it and there's also input data and how for example what does the land surface look like and do we have data to um to say what plants are growing where you know and like what's the resolution of those kinds of data sets as well that go into the model so it's it's a little bit of you know multiple components but I would say part of the reason why we're making some of these big advances is because of that increase in computational effort. I'm so glad you had a little nod to the observations there because yeah I think that's one place where the observations become particularly important is that they allow us to um to check what some of the models are doing from a process standpoint right we can't we can't populate the earth with enough observational towers to have the kind of like grid point by grid point data you need to completely validate a model simulation but we certainly can do the kinds of observations that you need to evaluate the important processes the important connections between the land and the atmosphere and so that's actually what the part of NCAR that I work at is is um is specialized in is we'll put for example instruments onto aircraft fly them through clouds to measure the efficiency of those clouds to see where the water came from in those clouds to see how pollution affects those clouds or similarly we put up towers in in certain ecosystems to measure the fluxes of water what Donica explained was the evapotranspiration to measure that flux from the land into the atmosphere. I think we have time for about two more questions. I've heard about the seeding of clouds to create rain or snow could you explain what that is exactly and why it's used and what the impact might be? I can at least start with the first bit and then and then questionably say something about the impact but if you think about how you create a cloud you need a couple components you need water in the first place to create the droplets but then those droplets actually need to condense onto something and those are often little particles in the atmosphere sometimes they're pollutants right so sometimes it's dust sometimes it's pieces of biological matter sometimes it's other types of pollutants that come out of our cars or factories so all of those become the little seeds or the nuclei onto which cloud droplets can condense when the atmosphere gets cool enough to do that so the question about you know seeding it's an interesting one because in some respects we're sort of seeding all the time just by putting particles or dust into the air but certainly there have been some attempts to put particles out there on purpose to see if that will enhance the production of cloud droplets and then hence the production of rain that's the idea is that if you can get a cloud to form you can potentially get it to precipitate one of the challenges we deal with when we talk or think about seeding in general is that if you put a lot of pollution in the air you actually have too many little seeds onto which cloud droplets can form and so the water ends up getting distributed the droplets end up being very small and as a result because they're so small they won't rain out so too much pollution in the air you actually shut down the precipitation process so in terms of the impact of seeding I think you could answer it from all sorts of questions like in general how does pollution impact cloudiness and rain or if we specifically go out to try to seed on purpose how does that impact precipitation and rain and the answer depends I guess one last question the question is about your mission I'm retired from the United States Department of Agriculture a research unit they were modelers as a matter of fact and they worked locally with farmers and ranchers and gave them data to help them know when to cull the herd when to fertilize what plants to what crops to plant so is your mission just to do research and then other people come to you and use it however they like or do you have an actual mission something that you're trying to accomplish so because we're the National Center for Atmospheric Research under this umbrella of a corporation of universities one of the primary reasons we do what we do at the National Center is to help support university research and provide research tools to them our research simulations end up being used in things like the IPCC reports that talk about climate change and so in that respect there there certainly is I think community interest in what we're doing I use the word community very broadly I think individual programs are doing a lot more to try to reach out to different stakeholders the agricultural part is more what Donica works on I can say from my perspective this summer I was part of a study to study hailstones and how damaging they can be in thunderstorms in Colorado in this region and that's a project where we're very interested in making sure we're having a conversation with folks who would be impacted by the damage from hailstones so certainly individual projects or programs I think are doing some of the work that you're asking about but but we are also a very basic research center at heart yeah I think Adriana captured a lot of a lot of the the basic mission of NCAR and I'll just add that there are there are plenty of projects at NCAR that do work with stakeholders some of the work that I have done is just some of the basic research with trying to understand how agriculture fits into the global climate system and and what those impacts have and so that's maybe less useful for an individual farmer at this point but we do have models that are that have been used to help identify when and where we might need to irrigate more you know into the future and so there are tools available like that with there's also the Colorado fire prediction model so there there are models like that that are that we're using to understand for example fire behavior but but they're they're also so they're research tools but they also can be useful and helpful for the community there are online predictions of air pollution for example there's an air quality model and that NCAR runs and they have some of those data online as well so you know I think I think that one of the main missions is to provide research tools for the for the scientific research community but it doesn't mean that we don't try to work with stakeholders and work with those groups as well we do we do also try and tackle some of those questions it's the best of our ability let's thank doctors Danica Lamberdansi and Adriana Bailey for a fantastic program I'd also like to thank the Long City of Longmont's sustainability program for their support and of course NCAR's Explorer series for their ongoing partnership with us look for another Explorer series coming up in the spring take care be well