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.