Hi. It’s Mr. Andersen and this Environmental Science video 2. It is on environmental systems. Understanding what a system is and how it works can allow us to tackle really hard, some of the worst environmental problems that we have ever had. A good example would be the Aral Sea. And so it sits on the border of Kazakhstan and Uzbekistan. And it used to be the fourth largest lake on the planet. And so the Soviet Union was irrigating off the Aral Sea to grow cotton and rice. And it was not super efficient irrigation. And so if you watch what happened to the Aral Sea from 1989 until to 2014, it essentially became a desert. And so we just see the South Aral Sea on the western margin. So the fish all died. The fishing died. And so we had economic collapse. And this was a problem with the system. We were not managing the inputs and the outputs. So the earth at the largest level is a system. It is separated from its surroundings. And understanding the inputs and the outputs allows us to manage a system. And so the big things we are looking at are the matter and then the energy. The matter remember is what we are made of. It is the atoms that make us and the rock and the water. And the energy is the ability to do work. Now if we look at the matter on our planet, it is actually a closed system. The amount of matter we have on our planet is conserved. We do not get new matter from space so we are stuck with the atoms that we have. It is conserved over time. If we look at the energy however, it is more of an open system. We continue to get energy coming from the sun and we lose that energy as heat. And so the thing about matter you should understand is that it is conserved. And this has huge ramifications. If we are looking, for example, for minerals. You can not just grow minerals. The amount of minerals we have on our planet are finite and we have to go find those minerals. If we are looking at energy, understanding the laws of thermodynamics. The first law is essentially the conservation of energy. Energy can neither be created nor destroyed. But the second law is also important. And that deals with the amount of useful energy. Every time we have an interaction when we are converting energy, we are losing some of that useful energy. And so understanding how a system works is done through systems analysis. If it does not change we say that system is at steady state or at equilibrium. And we can move it towards steady state using a negative feedback loop or away using a positive feedback loop. So big picture, a system is simply separated from its surroundings using a boundary. And we would call this a closed system, like the matter we have on our planet is a closed system. We do not get new matter. We do not lose matter, generally to space. If we look at an open system like energy, then there is flow from the surroundings into the system and vice versa. And so matter, on our planet, is made up of a finite amount of atoms. And atoms are organized on the periodic table. If we look at the simplest atom, hydrogen is going to have 1 proton and 1 electron. It is highly reactive. Everything else in this column is also reactive because it has a single valence electron. If we were to go to helium, helium could have 2 electrons in this first shell. And since it has two it is incredibly stable. So is everything else right here. If we were to grab an important biological atom, like carbon, it is going to have 4 valence electrons. Two on the inside, four on the outside. So it is kind of the lego block. We can build so many complex molecules off of that. And these are all through covalent bonds. And so if we look at methane for example, methane is 1 carbon, 4 hydrogens. We are sharing those electrons around the outside, so we have an incredibly stable molecule. And so the atoms we have on the planet are going to differ depending on where we are. So if we are looking at humans, think about this for a second, what are most of the atoms in a human going to be? We let’s break it down by percent composition. We are mostly made of water. And so it is mostly going to be oxygen and hydrogen. We are built out of carbon, hydrogen is so low because it has such a small mass. We are also going to have nitrogen, calcium, phosphorous. But in general we are going to be made by mass of oxygen. If we were to look at the water, so the sea water right here, what is most of that? We could break it up this way. It is mostly going to be oxygen as well. It is mostly made of water. We are also going to have salts, like sodium and chloride. But it is mostly made of oxygen and hydrogen. If we look at the rock, what is the rock mostly made up of? Oxygen. Now there is going to be silicon. We are going to have aluminum and iron. But in general, it is oxygen. And if we look at the atmosphere, that is going to mostly be nitrogen, but we are also going to have a large amount of oxygen there as well, and other trace elements. And so the oxygen in the atmosphere can eventually become oxygen in the rock. It could be oxygen in the water. It can be oxygen in you. It has to be recycled because we are not creating new atoms on our planet. Other important parts of this course will be understanding how water is polar and that affects its behavior. Understanding pH and buffers. And then finally biological molecules. So if you feel like you do not have a good enough background in these areas, I have put videos down below and you could surely watch those. The next thing we should deal with is energy. Energy was first quantified by James Joule using this apparatus. It has a weight that would fall. It would spin paddles inside water and so you could measure changes in the temperature using a thermometer. We were able to quantify energy, which is the ability to do work. We measure that, a nod to James Joule as a joule. Now when you talk about energy, generally you are going to hear things like watts. What is a watt? A watt is going to be a joule per second. So that is time. So if you are talking about kilowatts we are measuring the amount of energy that is being used over a given period of time. Understanding the laws of thermodynamics is incredibly important. So if a car moves from here to here it is converting energy. We are not creating energy we are converting it from one form to another. So where is the energy before it was in that motion of the car? It was in the gasoline. Before then it was in crude oil. Before then it was in ancient rain forest. Before then it was given off by sunlight and used by that rainforest through photosynthesis. But we are not creating new energy. We cannot create nor destroy energy. That is the first law of thermodynamics. The second law deals more with systems. So we are going to have inputs going into the system of the car. And then we are going to have outputs. And if we look at the amount of energy that goes into the car, we could think of that gasoline, the energy in the gasoline itself, we are using some that energy for the kinetic motion of the car. But we are also losing some of that energy in friction and heat and sound. And so what the second law of thermodynamics talks to is that at each interaction, at each point along that pathway we are losing some of that useful energy. It is eventually becoming heat which is non usable on our planet. And so understanding this balance is the area of systems analysis. And this model works well. Think of it as a bathtub that has holes in it. You have input. Then you have output. And if the amount of input matches the amount of output then we are at what is called steady state. If we could see that. But what happens if we have an increase inputs or an increase in outputs, what we can do is we can lose that steady state. And maintaining that is feedback loops. So if we look at a real system on our planet, a Swiss lake we would find that the level of the lake is going to be steady state. And in nature we find that almost all systems in nature are going to be steady state. So they are going to stay at the same level. Well how do they do that? They do that through feedback loops. And so if you think about it, as we melt the snow. As we increase the amount of water in the lake, the level goes up. We might have more drainage, and that is going to keep the level the same. What else might happen? Since the lake is really large we are going to have more evaporation off that surface and the level of the lake is going to go down. Now we have a smaller surface area, there is less evaporation. Now the level of the lake is going to go up. So that is a negative feedback loop. You could look at that at the level of the earth system as well. And so the earth is being heated. We are increasing green house gases. We are increasing the temperature on our planet. And so there is a negative feedback loop that takes care of that. As we heat up the planet there is more heat on the planet. What happens, we lose more of that heat to space. And so that is a negative feedback loop. The problem is that we also have positive feedback loops working on the planet right now. So an example, if we heat up the ocean, what happens? We are getting evaporation off the ocean. That creates water vapor and water vapor is an incredible greenhouse gas. What does that do? It heats up the earth which creates more evaporation of water and more global warming. Another example, we could look at this white area up here. So if we have a lot of ice that has a high albedo, it reflects a lot of the light back into space. What happens as we start to melt that ice, then there is less albedo. We are absorbing more of that heat and so we are increasing the temperature. And so did you learn the following? I would pause the video right now and try to fill in the blanks. But I will show you what it all means. And so we can think of remember the earth as a system. It has inputs and outputs. We do systems analysis to measure that steady state. Remember it could be negative or positive feedback loop. Remember the energy is an open system versus a closed system of the matters. So the matter is conserved. And that whole study is called thermodynamics. So hopefully you learned that. And I hope that was helpful.