Martin Hoffmann, Welcome to our next lectures for future this time again in English. Martin Hoffmann, I am Martin Hoffmann and I am active for scientific future up to Austria. So before I forget about all the lecture stuff. the nice part afterwards we can now go again to the Louis Gastgarten so anybody wants to join afterwards after discussion to have some drink some beer or whatever just come to the JKU campus and we can have chat about topics today or some other interesting topics so the other stuff I should remind you is the next climate round table this wednesday at six also in the gas garden at jku and now to the serious stuff from the lectures for future today so i'm happy to welcome University Professor Wouter Dorigo. Hello, welcome. Yes, good afternoon. So he comes originally from the Netherlands and worked the last 14 years at the Vienna University of Technology. Please correct me if this is wrong, but I took this now from the UCV so I think. Well, so he started at first at the Institute of Photogrammetry and Remote Sensing and since May 2017, Wouter leads the new research group Climate and Environmental Remote Sensing at Department of Geodesy and Geoinformation. geodesy and geoinformation. His main research interests are remote sensing of soil moisture and vegetation. So also the title you see from today's talk about water and environment. And he uses earth observation data to try to understand the quantities and the dynamics of trends and extremes and interactions of vegetation and the water cycle in the changing climate. So really important for our discussion of climate change and the next years to come, how the system will change or might change and what was in the last years. So as usual, I encourage all to ask questions via our menti.com link. So as well, you see it at the bottom line of our stream. And in principle, there is also the discussion in Zoom afterwards. So please join afterwards to our Zoom link, which you will find also in the description below. So before I talk too much, please, Walter, the stage is yours. Please share your screen and I'm happy to hear the presentation. Yeah, thank you, Martin, for the nice introduction. Just a confirmation if you can all hear me. Yes, perfect. Okay, you see my screen, right? No, that's not there. No, perfect. Okay, I forgot to press one button. Yeah, thank you again for the introduction. Yeah, this presentation is for a small but selective group of students, I hope. Before I start, I want to say that the title of my presentation is of course a rhetorical question. Will there be enough water in the future to feed us all? I think we all agree that we will not let anyone die. So we will find ways to cope with increased food demands, maybe reduced water availability. But it's more a rhetorical question in the sense that I would like to explain you more the challenges that we have to face in order to feed the zone. in order to keep us up. So let me just start with a very brief, very schematic overview of the Earth system. So the Earth system, well, as we know it, the natural Earth system is composed of the air, water, land, and life on Earth. But of course, as we humans are developing, as climate is progressing, we more and more eat pieces of the pie. And we humans, we drive ourselves or drove ourselves into the Anthropocene. So what is now? Before I start with the concept, I would like to have a very little poll. I don't know if it makes sense with so few people, but I would like to start with two questions. And the one just to have an idea of what your background of what your understanding is on water availability on earth. So the first one is, is on the water availability on earth. So the first one is, wait a minute, I will first start the poll. So the first, so if you scan the code, this QR code, you get into the, in the online chat, it would be good if someone could confirm if that's actually the case yes it works and i guess we need some time just because the stream is time has a short time lapse so just wait a little bit longer i guess so i have two questions prepared so the first one is what is the largest storage of fresh water on the earth? So fresh water is water that we can actually use without salt content, so excluding the oceans. And the second one is which portion of fresh water is stored in lakes and reservoirs? So what that is the fresh water as we know it so that we can readily access in lakes, reservoirs. So I see we've six bolts now and I also see that Jayana Bogic is still trying to enter lecture. Seven bolts, so I will now start the countdown to check out to move to the next question. Okay, yeah. I get, and the next question is which portion of fresh water is stored in lakes and reservoirs? I'm sorry for the typo. So ranging from less than 1% to more than 50%. And freshwater, so lakes and reservoirs also include inland seas, so like the Caspian Sea, as you can see here. So you can see two boats now. Three, four. Mm-hmm. Well, you're well informed, Asina. So the first question was, which portion of, which is the largest storage of fresh water on earth well actually most of you answered actually ice sheets which is correct and which is actually closely followed by groundwater which was the other major parts of the boat so if we look at the freshwater availability on Earth, so we see that you have 520 trillion bathhubs, and the bathhubs contain 100 liters of water, are stored as freshwater on the land surface. So that mostly includes ice sheets and groundwater, and only 0.3% is contained in lakes and reservoirs. That was also pretty nicely answered by you. So you know, most boats were set at one percent, so it's somewhere between 0.1 and 1%, so you're pretty correct with that. Yeah, other major storages are lakes and reservoirs. So there's the third largest storage of fresh water on earth and then followed by glaciers and a few other components. So I know now that I have to, I'm dealing with a pretty well informed audience and you have a good background, which is really nice to hear. And I would like to start with this image. So what we see here is the mean annual precipitation derived from observations. So we see clear patterns of areas where it rains a lot. So, for example, in the tropical rainforest in the amazon the congo basin in uh eastern asia or yeah indonesia and new genea and we see these typical patterns like we know them from from europe so western europe receives quite relatively a lot of rainfall compared to lot of rainfall compared to continental zones. We notice from eastern the US and also southeastern and particularly southern Asia, so India. So this is the, and if we look at the agriculture on the world, we see that a lot of the agriculture is basically following the precipitation patterns on earth so we again see here europe eastern us and also southern asia and southeastern asia apart from the tropical area so there is a lot of agriculture taking place in the areas where it rains most, which is what you would expect. And also, if you look at the population density, that also pretty closely follows agriculture and rainfall patterns. So the densest population here in Southern Asia, Southeast Asia, of course, in Europe, Eastern US, and some of the tropical parts. So this gives an impression that people go, people live where they can grow crops. And of course, traditionally, this was the idea. And there was no limit. Actually, population development was limited by the availability of water. But if we look at the discharge and the river discharge here at the lower right, we see that the rivers with the largest discharge, so that these are the areas where it rains most, so the Amazon basin, the Congo basin, Southeast Asia, which is an exception, but also Northern Europe, are actually not following these patterns where it rains, where we see most aquaculture. And this also shows that particularly, for example in the western US where there is not so much water, not so much precipitation, which is exemplified by the reduced levels of runoff, actually there is a lot of agricultural production and this production here is mostly fed by irrigation so our earth is moving more and more towards a state where aquaculture is not no longer driven anymore by the classical patterns of rainfall but more and more by irrigation water extraction from either rivers or from groundwater storages and with that i would like to move to the second poll i would just give him get an impression again so the two questions are how much water is used for irrigation on the global scale on the global yearly scale and is that more or less than the annual discharge of the danube river in vienna so the annual amount of water throwing flowing through vienna through the danube river so i go to this go to this. So you should be able now to access the online tab again. Is that correct? If it doesn't work, you can also reply by Zoom, of course. So... So, yes. And then just the next question, which is, is that more or less than the annual discharge of the Danube River in Vienna? More. Well, there's a unanimous vote, I can already tell you. So the first question, how much water is used for irrigation? The answer was there were four answers in total and all of them, all of the options were chosen. So actually there is not enough awareness yet how much water there is being used for irrigation. So in total, we on average, on the yearly average 6 700 cubic kilometers of water are being used for irrigation and if we look at the discharge of the annual discharge of the danube river which is 1900 cubic meter per second on average on a yearly basis which is 43.5 cubic kilometers per year. Then it is 154 times the yearly discharge of the Danube River. So it is an enormous amount of money, enormous amount of water that we use to feed the world. And this is, if you look at the global water cycle fluxes, the fluxes are the movements of water through the water cycle, so going from one storage to the next, for example, from glaciers to the ocean through river discharge or from evaporation over the ocean to the land surface and to precipitation. So if you look at the storages and you look at the water use which is the blue water use is only a tiny fraction actually of the amount of precipitation that is falling on the land surface. But as a consequence of the inequality of where it's being produced and where their precipitation falls on Earth, mostly the tropical rainforest, there's a lot of water used in areas that are very dry. So let us look at something which is called the water footprint of humanity. And this is the total amount of green water. The green water is the precipitation following the earth. The blue water, which is the service and groundwater used for irrigation. And the gray water used of humans. And gray water used is, here it says pollution, but it's the amount of water that is used to process food, used for industrial use, used by humans for showering, for domestic water use. And that is the footprint, the average footprint on Earth. So we see a lot, again, a lot of water is being used in the agricultural regions which is mainly green water blue water but also some on some of in the gray areas for industrial production and the as the world's water use is not it's not always used uh they are what's being produced there is a kind of trade of order just like the trade of goods there is a trade of water you can look at water as a yeah well you need water to produce for example our coffee our daily coffee you can we need water to produce the fruits that with the bananas that we eat for breakfast and that water can be expressed as a kind of water footprint which is very important in terms of the water balance of the global water water balance and i say i call it here an imbalance because we're not consuming the water where the foods are being produced so there's a kind of trade of water. And these are the ingredients in the areas that are net producers, next exporters of water. So we use a lot of goods are being produced, for example, in the Amazon, in Argentina, in the US. And these goods, these aquaculture goods have been exported, for example, to Europe, to Japan, so into areas where there is not enough rain, or we have a high quality or high level of consumption. And the global average footprint of water is approximately 1,500 or 1.385 cubic meters per year. But there's a large discrepancy between who is using what. So if you look at a relatively poor country like the Democratic Republic of Congo, which uses an average 500 cubic meter per year, and the US citizens, who uses almost 3,000 cubic meter per year. And this high usage of water by US citizens is mainly because of the dietary, the diets of, in our Western world. So for example, meat production requires a lot of water because we need to grow soil, soy, sorry, in the Amazon or in the US itself that's fat to the animals to the cattle and that produces meat that when it's slaughtered it's uh you have great meat on your plate but in indiana there's a lot of food that goes into cow that's been used to feed the cow and this this food produced are needed to feed the cow uh uses a lot of water to be produced. Yeah, so we see actually in Europe, we are a net importers of water. And of course, also the dry or the very dry countries in the world like Saudi Arabia or northern Africa, also southern Africa, but particularly also Europe because of our dietary habits. And if we look at the trends of the water withdrawal, we see that the service water use is increasing over time. So it has increased, of course, with increasing demand for food. So there are a lot of more mouths to feed. But also groundwater use has increased enormously. You see particularly, for example, in countries like West Asia, which is basically the Middle East, or Northern Africa, there is a lot of a strong increase in the use of particularly groundwater use because surface water use is limited. If you don't have runoff, you cannot use surface water. If you don't have rivers, you have only one major river in northern Africa, so the Nile River. So you need to tap more and more groundwater to produce the food that needed to feed the people. And in countries like, or in bridges like Southeast Asia or Southern Africa, there's more service water is being used. So river discharge. So the main, so the Mekong River, for example, is greatly used to for irrigation and also in australia most of the runoff the discharge to reverse is actually being used for food production yeah there's one more of course if we want to know what is happening in the future if we have enough water to feed us all in the future we also need to know what our world population is doing but just to give you an idea of where we stand now so until the middle of the centuries in the 1950s or 1940s 1950s the the amount of people living on Earth was steadily increasing, but it really dramatically increased after the Second World War. So just to give you an example, so we're now almost with 18 billion people on Earth. So it took about 120 years to go from the first billion to the second billion of people on Earth, but it only took 12 years to go from 6 to 7 billion people. And until the end of the century, so 30 years from now, we're likely to be with 2 to 3 billion people more. But of course, human predictions, human population predictions are extremely uncertain. And that is given here at the right. So we see our, these are the margins we see on the predictions until the end of the century. So the range is somewhere between 7 billion, so approximately where we're now, to 15, 16 billion, so that's double where we are now. And that can change dramatically also with decisions being made, with political decisions being made. So, for example, we don't know if China changes from a two to three kid policy, then this may change, change of course dramatically the number of people living on the earth and there are a lot of the pandemic may have impact so there are a lot of factors actually driving the the uncertainty in the new human population predictions So, this is one factor to take into consideration. One important thing is also that the developed countries were more or less stable. So in Europe, we know that we're not, there's actually some countries with already slowly decreasing number of births of the population total. But particularly in Africa and southern Asia, it is expected that there will be an enormous increase in population still to come. So what are the trends of population and water withdrawal? So if we look at the right plot, we see that the trends and population here in blue, and we see that the trends and water withdrawal in percentage is, has the same direction, obviously, but it also is larger than the population because we have different demands in our diet we use more and more foods that require more and more water so if we um yeah we we don't need only cereals we have a lot more fruits highly intense water intense fruits and so on more meat consumption so that requires more meat consumption, so that requires more water, leading to a change in water withdrawal, which is greater than the actual population growth. And this is also reflected by the GDP, so the gross domestic production per capita, which is also increasing, so we have more and more luxury so the increase in water withdrawal is expected to change and increase still and here we see that um the global fresh water withdrawal is largest in agriculture and but also industries increase and municipalities so So we have more swimming pools than 20 years ago, but also we take more showers. So we have higher living standards than 50 years ago or more. Yeah, and water withdrawal is actually becoming an issue. So if we, of course, groundwater is not an unlimited resource of water, neither is service water. And that was dramatically shown a couple of years ago in the Western US. And that was perfectly monitored by satellites, satellites is my field of research, satellites they measure the gravity of the earth and from this gravity we can actually infer the amount of water, the change of groundwater and we see actually that there is enormous depletion in the course of only of two years in the western US and particularly in the great, in the central valley where most aquaculture production is taking place in the western US and particularly in the central valley where most aquaculture production is taking place in the western US. And this was dramatically reflected by for example groundwater levels or surface water levels. So this is, well this is a holiday destination for many people but if you look at image, it doesn't look like a very attractive holiday night destination anymore in this picture. So water levels dropped dramatically. So there is a shortage. There's a temporal shortage now. um a shortage there's a temporal soldiers now it's going back to normal again but we have to yeah we have to count that this is becoming more and more frequent such events and if we look at the um if we combine the water stress um or the water use with the increasing population water use with the increasing population then we see that in the uh in the in 2040 so only 20 years from now there will be a lot of will be almost 2 billion people or actually this is already happening in five years there will be already 2 billion people with in areas plagued by water scarcity so really scarcity and two first of the world's population living in water stress region. And this image, what is it showing that it's some necessary ratio of withdrawal to supply. So everything more than low means that there's more withdrawal than there's taking water from either service waters or from groundwater, then it's being recharged by a precipitation or snow melt. Yeah, not surprisingly, these are mainly the dry areas in the world, but also these are also countries with high agricultural production. For example, Spain is largely the agriculture in spain is largely fed by uh irrigation so that this we have to be aware of this so that's not far from now and then apart from that there's another um stress factor, hidden water stress, which is called salinization. So not all of the water, so let me start with this image here at the upper left. So groundwater is extracted, groundwater is pumped, and this allows, so if you remove water, there is an increased inundation or intrusion of salt water into the land surface, particularly coastal areas, where more and more suffer from degrading quality of the freshwater. So in salinization of the water. And this is shown in this image, particularly in yeah we see the lowland areas the delta regions so in northeastern europe or in florida and here and so yeah mostly all the regions will more and more suffer the intrusion of salt water if more water is being pumped up apart from that there is also more water is being pumped up apart from that there is also natural terrestrial origin for example on areas where there is with inland seas so there is an um yeah some salt lakes here so there are basins also in australia where the rivers are flowing into the interior of the continents is evaporated and what remains is the sulfur in the interior of the continent. So these are all natural ones, but also salinization, the degradation of the groundwater is taking place due to wrong use of the borders, so particularly in Central Asia and Southern Asia, but also here in the irrigation areas in China. So that means water is used for irrigation, water evaporates, there's too much evaporation, and what is left behind is salts. And if you continue this process for a long time, then your salts get saltier and saltierier and your water degrades the water quality yeah and if we want to have a look at what is um which amount of water we can use for for growing, we also need to look at the multiple roles water can take. So water is not only used to feed our population, but it has a lot of functions in our earth system. So it has a lot of ecosystem service functionality so we of course we we need to drinking water it has an aesthetic function recreational function so we want water we don't use we don't want to use all the water from the noise if they say for example for drinking water we want to keep that there we don't want to reduce the Danube river to something that's um to the size of uh of the Wienbach for example or the I don't know what the Steyr is that uh is that that flowing through links I think so right. It's providing an habitat for life, so that's, we need this for biodiversity for food production for fish for for cleaning water. It drives life of course not only water drives agricultural production but also timber production bio so ecosystems like yeah natural forest we need um and we need the forest not only for timber production of course but also the foods are needed to store carbon, forests are the most important mitigators of climate change by absorbing CO2 from the atmosphere, by photosynthesis and so on. So it's really, really important for multiple purposes and we need to find a trade-off that all purposes are actually equally served and this brings me to this image which is um shows the water food energy Nexus this is actually what I was shown before the ecosystem service the ecosystem function water may have and there is a kind of trade-off. So we have our water systems here, we have our energy systems, food systems, and there is a continuous exchange, an exchange balancing like juggling to keep all balls in the air. So if we want to, we need water to clean drinking water. And if we use water for for example, we it's been used for food production, or also energy production, for example, biofuels, but also for the processing for the cooling water of the plants that we're using, still using, hopefully not for a very long time, but still we need cooling water for navigation, for shift, trafficking, and yeah, the food systems here. And we have our population, our pressures, so climate change population growth um also if we want to remove to renewables we need hydropower so we cannot use all the water that we need to produce food but we also want to keep our clean energy our hazard powers particularly not sure it's extremely important, a renewable water source. So that's an enormous complex game we need to keep alive. And to make it slightly easier as an overview again, so we have here our water, food and energy. So we need water to irrigate land, for food processing itself, water for livestock, water for cooking, and also one of the major consumptions of water is not food production for ourselves, but to food production for our livestock. Yeah, and our food production again is competing with the biofuels, which I think is the wrong path to take to produce, to sacrifice agricultural land for energy production, but still it's there, it's being done. So rapeseed is being produced so that it's competing with the food resources. And energy needs water for heating and cooling, but also energy is needed for clean water to keep for desalination in desert areas for water treatment and so on so there's a very complex game and what i forget to mention are also the pressure from outside like climate change population growth and governability so the socioeconomic decisions and developments just to give you an example of the dietary water requirements. So what do we need? So this is the dietary footprint, the water footprint, if you look at it in per grams of product, but also if you look at it per kilocalories. But of course, and not if you look at proteins, but if that is fruits, but if you compare meat consumption or meat production to other sources of proteins, for example, milk or particular nuts, rice or grains here, it has a much larger water footprint. So meat is not only about methane production, it's not about land consumption, but it is also about water consumption, which makes it a very disadvantaged resource of food production, very inefficient source of proteins. And these pictures, this picture is more or less reflected also by the carbon footprint, which of course interact because meat production has a large connection to the carbon footprint, not only because of carbon equivalents, not only because of methane, but also because of the land consumption. We all know the examples of the Amazon forest which are being cut to produce soy, beans to feed the cattle somewhere else in the world. So also meat production has a very large carbon footprint, both carbon and water. And to show you the link also to the energy production, so this is the water consumption by energy sector. These are the classical ones, so the gas, nuclear to cooling of coal plants, fossil fuels and also the biofuels. And we see that the more or less the water consumption by for the classical energy sectors will remain equal. But the water consumption for biofuels will increase because, of course course we need land we need to grow crops or to grow the fuels yeah and i would like to use the second part of um or last bit of this talk to um to focus on the role of climate or the climate change which is mostly my field of research and i would like to start with this very simplified world which is showing the natural drivers of plant growth or food growth if you like so what we see here is that in blue, that is 61% of land surface is water limited, which means that the more water you put into the system, the warm water you use in these areas, the more food or the more crops or vegetation you will be able to grow. And if you, at the same time, if you take away water, for example, if it gets drier, precipitation gets less than the production of food or vegetation will reduce. And there's 23% of the land area which is temperature limited, which means if you would increase the temperature of the earth, then in these regions, you would actually increase vegetation growth because it's now still being limited by cold temperatures in winter mostly. You see here that in these images is mostly the northern latitudes. And then there are some areas which are radiance limited, which means there's enough water, there's enough, the temperatures are high enough, but it could use more sunlight to grow. These are areas where there is, for example, in the very northern latitudes where there is not so much radiance in winter times because it's dark in winter or the tropical areas here for example and here or there's a lot of cloud cover and this cloud cover obstructs from the radiance from falling on the vegetation and the radiance is being used for photosynthesis or required for photosynthesis. So that's the natural situation. So I would like to have a third poll to test your knowledge on climate extremes. And the two questions are, while we're first starting, come on. And the first question is, will climate change lead to less or more precipitation globally? precipitation globally? And a second question is will climate change lead to fewer or more extremes like droughts and floods? Yeah, so 40% of you answer there's less precipitation with climate change, global warming, and 60% answer there will be more precipitation. I will show that in the next. And the next question, will climate change lead to fewer or more extreme events. Okay, so apparently the droughts that's clear, or the storms, floods, they will actually be... Well, let me just first go to the examples. Will climate change lead to more or less precipitation? The first question, which was, well, let's say 50-50 of the answers we're actually all climate models like shown here agree that climate change will lead to more precipitation which actually is a good a good um announcement so we will have more precipitation on earth i can tell you why well the reason is with it increasing, with global warming, with increased temperature, more water can evaporate from the ocean. So more moisture than the atmosphere, the air can hold more moisture, and more moisture means it can precipitate more. It will be more rainfall. So there's actually very little doubt about that, that it will be wetter in general, on average. But unlike the changes in global warming, which is shown under the upper panel, so there's a general agreement and a general tendency everywhere around the globe that it will become warmer. But if we look at precipitation, then it's actually, the pattern is not as clear. It will, on average, it will get warmer, but it will not be, sorry, on average, it will be wetter, but it will not be wetter everywhere so there are regions for example the northern latitudes or the tropics part of the tropics and actually also the sahara as well where climate models agree that it will become wetter but there are some regions for example the mediterranean in just up to austria but also australia southern africa but also the amazon basin where the indications are that it will get drier actually so there's a disparity between regions and will the climate become more extreme? Well, we all of course, we know from the media that it's, well, Australia has its words. It dries in December, the heaviest fire season in history we know that um we probably noticed that last winter was extremely wet in australia and in carinthia flooding in china worsens um this is well this is extremely warm temperatures in greenland from the arctic and the devastating droughts in Ethiopia, Somalia and Kenya. But of course, this may be a bias because there are more media. There's much more coverage of extremes in the media. But it's actually, it's really true that the climate gets more extreme. And I will show you now. So, but, um, just to give you an indication, what's what happens close to home or actually at home and the Pannoni Basin. So was it, um, do you remember these trials? Probably not. Maybe the last one, but they have been in the years 2000s and 2010s. There have been four pronounced droughts in the Pannonian Basin. The Pannonian Basin is mostly here. basin between the mountain ranges surrounded by the mountain ranges of the alps canarian and the and then slovakia and romania so there has been um a lot of trial dry events uh in this area which has actually led to yield losses of 25 to 40%, which is really substantial. That's not, that's really a lot. And these, this basin is still mostly rain fed. So we need to be aware that this is still rain fed. And now more and more the discussion is to use also Danube River water to irrigate more of the land surface here to mitigate the impacts of climate change and of increasing droughts. Just to give you one slide on drought, so what is drought? So you have different types of droughts. The first one is a meteorological drought, which is a period of reduced precipitation. So a shorter term dryness, which may lead to an agricultural drought. So the soil is dry, so this may lead to increase evapotranspiration, some vegetation stress, and this may then turn, if the drought prolongs over a longer time frame, it may turn into a surface and groundwater deficit leading eventually to an agricultural drought. So for example, the Danube River carries river carries less water, groundwater reservoirs deplete, and so on. And in the end, this may lead to a socio-economic drama, so with major impacts on the environment, on the economy, on society. So for example, food crisis or increasing prices of food and so on, displacement of people. So that's in the worst case, what a drought may lead to. So if we look at the more realistic scenario, what is driving plant growth for agriculture production? Then it's the normal drivers of temperature, water, and radiation plus the extreme events of droughts, deepwakes, wildfires, plus bug outbreaks. You may have lacked effects, so maybe dry in one year, but maybe it's next year or only two years later, you start to notice it because it takes a while until the tree for example is being affected. But you also have on the positive side you have adaptation strategies of plants. So plants may adapt to changing drought water conditions. So if you have a prolonged drier episodes prolonged drier episodes. Plants may have a more efficient way of using the water for photosynthesis. Human impacts of course, they're mitigation measures, so irrigation, land use, logging, so land use change. Humans may use different crops plant different crops and there are a whole lot more uh yeah salt degradation and so on wind throw and so on and so forth so it's a very complex thing um just to give you an example the recent greening of the earth so what has been noticed over the last few decades is a greening which means the amount of biomass on earth on average has increased and we see this here co2 um this is the increase this is these are trends of lee vary index the variance is a measure varie index the varian is a measure vegetation uh rigorousness and vegetation health or density and we see that mostly in in many parts of the world there has been an increase in vegetation and this has been due or or the major driver of this has been the capability of plants to use, to increase photosynthesis by the increased levels of CO2 in the atmosphere. So CO2 is necessary for photosynthesis. If you increase the amount of CO2 in the atmosphere, you actually boost the aquaculture production. But of course, this only works if there are no limiting factors. Just to give you an example, this is the pre-industrial level here, 280 parts per million. So if we were currently over here, almost at 420. we're here uh almost at 420 so the relative yield of plants increase particularly of soy wheat and rice not so much of corn or maize so the relative yields increase with co2 which is a positive side effect of increased co2 levels but of course this only works if there's nothing else that limits plant growth that is exactly the problem we have here because um this only works if we have enough water and this is not the case in most of the parts of the world so this is the percentage of change in yields predicted until the mid of the century and we see that the degree of the yields will increase or are predicted to increase in the northern latitudes where we have enough water where it's not too hot but will decrease in most parts of the world if we continue the way of cultivating crops as we do now. I'm not going into the agricultural aspect of this so much, but we may change the crops we grow or the way we grow crops or we use the way we use our water so make our water irrigation more efficient for example or maybe not grow very water intense crops like watermelons in areas where there is a lot very little water like in Spain or northern or in even in Saudi Arabia which is a very big producer of cereals nowadays yeah and then one thing one other aspect to climate change and water availability is just the variability of the water availability change. So these two contradicting things. So East Africa, these are two years. I'm sorry, I forgot which years it were. But East Africa's deadly floods are a reminder of the Regis-Porte-Avasta protect. So the increasing floods of Eastern Africa and there's also droughts in Eastern Africa becoming more frequent and more devastating. So this may seem contradicting of course, so one in the same region experience more extreme events in both the wet and dry direction. But if we look at the intra-annual variability, so these are the predictions of the water availability in four different scenarios. So the scenarios are, yeah, these are the, I'm not going into the scenarios, but it's the irradiated forcing and the standard as social economic pathways which is a um used by the um the ipcc um yeah to to have different socio-economic uh evolutions in which we can develop with all of these scenarios which is the key measures of this plot show that there will be an increase in northern winter precipitation as we see here but with the increase with stronger heating of the earth it will be more intense stronger heating of the earth, it will be more intense. But at the same time in our summer, we also see that there is, um, yeah, June, July, August, there will be more extreme, uh, dry drought. So there will be a strong interannual variability. Yeah. Yeah. Yeah, this is basically shown here, which is the coefficient of variation. So that shows the average spread of dry and wet spells, wet events. So everything that is green shows an increased variability, interannual, intraannual variability, or in general, intraannual within the year and between years. So actually all years or all areas on Earth will experience more variability towards the end of the century. And that's both for April to September, so our summer period or our winter period. So we need to adapt to this. So we need to adapt to this. And one other factor I would like to mention is that even though precipitation may increase, we saw this, I go back here, we saw this increase in precipitation predicted for northern land masses. If we look at the soil moisture, which is actually the water stored in the soil, it's mostly linked to a depletion. So an increase in precipitation does not necessarily mean that there will be an increase in the available water for crop production. And this is because precipitation precipitation increases but also the atmospheric demand so the evaporation increases so which in the end as a sum of all the components may lead to a desiccation of the soils so So this is the predicted future water stress. So that's the cumulative hydroclimatic stress in the worst case scenario. But if we continue like this, we will be facing this worst case scenario. So this is the normal drivers um so yeah i'm i'm not going into detail about stress but everything more than 100 will be means increased stress and if you put on top of this the population pressure and the changes in our dietary behaviour or the continuation of our dietary behaviour, you see that the increase is even stronger in many regions. So you've seen this reflects the enormous population boost that is expected for sub-Saharan Africa. So to summarise, the current trends, negative trends that we see is climate will become more extreme, more variable, both within the year, between the years. Increase in carbon dioxide will rise the temperatures on Earth, which we all know. But this will also, on top of warmer climate it will also increase the drying of the soil so soils become drier in those most places of the earth energy is increasing population density which will is will be causing increased water demand uh gdp will continue to increase we've seen this during the pandemic still, even though the global gross domestic production still increased despite a global crisis. So dietary shift will be shift to more meat and dairy products. This is still the general despite a few vegetarians and vegans we're feeling in western societies uh first many parts of the world were first moved to more meat-based and thyroid-based diets and there will be a more and more competition between be a more and more competition between water resources between aquaculture biofuels and other uses like energy production of course there are some positive trends that we're facing so there will be more precipitation globally so that will balance a few of these negative aspects so that will balance a few of these negative aspects. Increased CO2 levels will, in some parts of the world, continue to act as fertilizer, although the extent of it is still unknown. And some crops may experience increased water use efficiency. But water use efficiency may also be promoted by us humans. So for example, by improved irrigation practices for adaptation as well, new sorts or shifting cultivars. Yeah, and then to come back to the initial slide, will there be enough water in the future to feed us all? Like I said, very likely there will be, but it will be very challenging, but not impossible. And in order to do so, we must change the life we are living. We must change our diets we must yeah be more efficient with our water resources and the ideal situation will be what we see here so it's not a transformation from an unbalanced situation into something that is more stable so more resilient so cultivars something that is more stable, more resilient. So cultivars, food systems that are more resilient to droughts, to extreme events, energy systems that are less space demanding, less water demanding, and of course the water security. With this I would like to conclude and open the floor for discussion. Thank you very much. So, well, thank you very much for the nice talk. It was a lot of facts. So I was just, So really, really interesting. And also a lot of numbers. And this is pretty cool. So I would be... Because I'm the scientist, you know. I would be really interested in how you get those data. Because you are doing this with satellites, right? How this works that you make the data and um now what i've shown here is very little based well some of the things i show were based on satellites but um most of them of course the predictions are based on models can only be based on models um what we use to the satellites for is for example to monitor what's going on in the world for example the changes in uh in groundwater consumption that can be very nicely tracked with satellites another thing that can be nicely checked is uh how the vegetation reacts on this uh how the vegetation reacts on uh yeah on climate change so the greening of the earth that's something that has been made possible only through the use of satellites and also the the moisture of this service that can be very nicely tracked with satellites and various other factors like increased in precipitation for example, that can all be tracked with satellites. What kind of satellites? It's a very different related to the sort of phenomena you're looking at, the variable you're looking at. It can be anything in the, what we as a research group use are microwave satellites, which measure actually radiance that is emitted from your surface. I'm not sure if the background of the student is a more technical one or yourself is more technical one or not. You usually it's more economics, but. It's more economics, not you usually it's more economics but it's more economics okay so it's um yeah it's it's basically um yeah i mean sorry your question was again what the how the measurement is taking and so but so I because I'm from coming from the from the physics so in principle yes if you say you measure with the gravitational field or this sounds really interesting so I have thousands of questions practically but anyway I can briefly summarize it. So what is being measured is either the sunlight that is reflected by the Earth's surface, so the amount of reflection. So you can see the satellite as a camera, as a photo camera, and it measures the intensity of the sunlight that is being reflected. It's the same principle as a photo camera that also measures radiance, light, sunlight that is being reflected. That is what cameras do. And you can do the same thing with satellite. If you take a picture of, I don't know, a landscape, then what you see as green is the amount of radiant sunlight that is reflected in the green domain. So the more, if you see something like green, if you see vegetation as green, this means that more sunlight, more green light is reflected by the plant than, for example, red light or blue light. And satellites use exactly the same principle to measure the vegetation density. But you can also move that to other wavelengths, so beyond the visible spectrum, beyond sunlight, so for example, the earth itself emits radiance and from that you can can derive various physical quantities is that thanks yeah so and maybe you can switch off the sharing if you don't need the slides at the moment. And then we have. Yeah, thanks. So another question coming from the audience was, actually, what can be done to avoid such water extremes, wetter, wetter extremes like trouts, and specifically concerning agriculture and the methods used there. So either what can be done or if, if can, can be there be done can we do something about it exactly um yeah there's two things in that question uh the first thing is can we avoid weather extremes is can we avoid weather extremes? I don't think so. Because then you need to strongly interfere in the Earth system. And I don't think that's possible. Well, the only thing we can do to avoid such weather extremes is to reduce greenhouse gas emissions again. And then we have a long-life effect. But what we can do is avoid the impacts of such weather extremes like droughts. And in agriculture, one of the things we are working on is we try to predict extremes, or at least the impacts. extremes, or at least the impacts. And we try to guide farmers or water authorities that there will be extremes, there will be droughts, and that it's about time that you start, for example, irrigation. So you're prepared for a dry coming up so that your soil is dry enough to mitigate, to cope to that drought. What currently, what nowadays is still the fact is that a lot of the irrigation on earth is very unsustainable. So for example, a lot of irrigation is still being done through flooding and flooding, like for example, for rice crop is an extreme case, but also cereals, cotton production is extreme case. Again, the central ACM, there's a lot of cotton production, but also in the US and they just flood the landscape. And a part of it, of course, moves into the soil part of the irrigated water, but a lot of course, evaporates as well, because these areas are extremely arid, with a lot of incoming sunlight, and there's a lot of evaporation, a lot of water lost. So there's a lot to gain still in these areas. Yeah, so that's the major thing. And another thing is not only improving the efficiency of irrigation systems at the location, but maybe also to look at, to have a more holistic view of production, to grow crops that are suited to the landscape they are growing. So if you have a crop that is real resistant to drought, grow them in areas where there is a lot of drought. And if you want to grow crops that are very water demanding, don't grow them in the Sahara mean, for example, Egypt and Saudi Arabia are big producers of potatoes and cereals, which is of course ridiculous. It's all based on groundwater. So it's not an unsustainable use of that water, of course, because these resources are not being recharged. So for that, of course, that's very difficult to establish because you need to have a kind of global optimization and food production. So as in many other areas as well, there's a lot of room to getting better, at least. So that's the one positive point right you can get better and then solve many problems getting better perfect so i would like to stop here the live stream thank you very much for the talk and now everybody who wants to join for the discussion further discussion or any questions comments just join the zoom link as usual in the video description and see you next time in two weeks there's the last presentation from the lecture for future this summer term it's about uh energy and and usage the professor from the fhaH in Upper Austria is discussing problems about energy production and so on. Thank you much. Bye.