Hi. It’s Mr. Andersen and this is environmental
sciences video 18. It is on land use. You are probably familiar with this skyline. It
is the Las Vegas strip. But it is actually a small portion of the Las Vegas area. This
picture was taken in 1984 and I am going to show you a picture taken in the same location
in 2011and watch what has happened to Las Vegas. So we have had huge development into
the periphery. We call that urban sprawl. And it brings with it some ecosystem impacts.
And so land development will always occur with humans. But we are seeing a movement
from the rural to the urban, into the cities. We call that urbanization. That is actually
a good thing. It can leave more land conserved for ecosystem services. The problem is not
only are we seeing growing cities but we are seeing growing transportation. We are getting
highways, the arrival of the car. And that leads to urban sprawl. The cities are spreading
out and we lose all of the benefits of the city. Also as people move out they take their
tax base with them and that can lead to urban blight on the inside of the city. And so we
are getting these ecosystem impacts. With urban sprawl we are eating up the land around
the city. So there is a loss of land and also we have pollution. So we can have air pollution.
We can have light and noise pollution and heat pollution. We see that in the urban heat
islands. But we are always going to have development. So people are putting forward this idea of
we need growth that is smart or smart growth, to avoid some of these negative consequences.
But in parallel to that we are also trying to conserve land. And we have been doing this
in all countries around the world. In the US this is highlighted in the national parks.
We have wilderness areas, wildlife refuges. And then around cities we are trying to protect
the wetlands and the forests. And so this is the movement towards the cities. In 1950,
this is where people were living. 70 percent of the people on the planet lived in rural
areas. And less than 30 percent in the cities. Watch what happened over the last 50 years
and what they predict into the next 50 years. Those are going to flip-flop. And so we are
getting this movement to the cities. This has already occurred in a lot of the developed
countries. And so the US, it is already over 75 percent of the people are living in the
cities. But we are going to see this in developing countries. As they come online we are going
to have more people moving into the urban areas. You can see this in an age structure
diagram. This is females in a rural county in Iowa. And you can see that once they go
to college the numbers drop off in that area. Now why is that? In a rural setting, with
industrial agriculture there are not jobs anymore. And so you can see that they are
moving into the cities. This is the growth in a urban area of Iowa. And so we are seeing
this movement into the cities due to opportunity. You can get jobs there. And once you move
into the city you are not going to move back. And so this transition is going to occur into
the future. It is actually a good thing. If we think about low density housing, I want
you to concentrate on the green area here, let’s say we have nine houses and they are
all spread out. Let’s say this is in a subdivision. Each of them have their own yard. And we have
to put roads to each of those, and what is happening is we are losing that valuable land.
But if we get the movement into the city, so we take those same nine houses, stack them
on top of each other, let’s call them apartments, now we have higher density housing. We can
have a park that they share and fewer roads, and now we leave more of that land outside
the city. And so cities are actually good. The problem is urban sprawl. And so if we
put a city right here and then put a couple of roads to it, so back around the turn of
the last century, cities started to grow. And that is because there were opportunities
there. And so if we say this is the housing density, so we are going to have the greatest
density inside the center of the city, there are opportunities there. It is really hard
to get into the city. We do not have a lot of roads. We do not have a lot of transportation.
It is hard to get out of the city. And so we are going to see these flourishing inner
cities. Now what happens though, around the last half of the last century, is that we
have the arrival of roads, infrastructure and the automobile. Now it is easier to get
in and out of the city. And people started doing that. They started buying up lower density
housing. And so what you get is this urban sprawl. This movement away from the city.
And this is a positive feedback loop. The more people move out, the more roads there
are the more tax base there is and we are going to get more movement out. And we are
going to encroach into the area around it. They are also brining their tax base with
them. And so that leaves, a lot of the time urban blight, areas on the inside of the city
where people are not actually living. Now this is kind of a United States problem or
it is more of a problem in the US. And so if we look at this graph, this is the area
per person. And so these are all US cities. And so in US cities like Houston and Phoenix
we have low density housing. If we look on this side, on gasoline use in the US we are
going to be using more gasoline. And so since cities in the US formed later than those in
Europe, and also since we were using the automobile and we had increase in highway structure,
we have had this sprawl be a larger problem in the US. It brings with it problems. In
all cities pollution would an example. This is smog in Mexico City. We also get noise
and light pollution and heat pollution. If we look specifically at heat pollution we
are seeing these heat islands where cities are. And so this is a picture of Manhattan.
This is Central Park right here. And then we are looking at a map down on Manhattan.
You can see Central Park right here. And areas that are really green are areas that are rich
in vegetation. But watch what happens if I now show you heat coming off of the land.
You can see that we are going to have higher temperature, hotter temperatures where we
do not have that vegetation. So as we build up those cities, it is actually absorbing
that heat and creating a heat island. And so how do we solve this problem? Well one
thing would be to plant a lot of trees. But how do we return people to the city center?
A lot of people are going around this idea of smart growth. And so we need to create
desirable locations in the downtown, walkable neighborhoods, compact building design, sense
of place in the city, growth boundaries perhaps around the city so we force people to stay
within those settings. Now there are pros and cons of all of these, but sprawl is definitely
having some negative impacts. Now outside the cities we have also have been trying to
preserve land. So the National Park Service was instituted and we have National Parks
like Yosemite and Yellowstone National Park. We try to protect this area for people into
the future. Now if you have ever been into a park we still have roads there. We still
have infrastructure run by the National Park Service. We also have wildlife refuges. So
those are administered by the US Fish and Wildlife. So this is ANWR. This is in Alaska.
It is a national wildlife refuge. These are set up to protect specific species. In this
case it is the caribou. And then the strictest of constraints are in the wilderness areas,
which are administered by all four of these entities. Inside a wilderness area we try
to limit roads. The only way you can really get in is walking, riding a horse or by canoe.
And so we do not have mining inside those wilderness areas. And so we are trying to
protect these areas so they are not developed into the future. And we are also, on a micro
scale, trying to protect wetlands around cities. This is a forest that has been protected in
Poland since the 1300s. So if we put boundaries around that we can number one mitigate it.
So we do not have development into these valuable areas. We can restore them when they are damaged
or remediate them. All of these are very big things that we can do around cities. And so
did you learn the following? Could you pause the video at this point and fill in the blanks?
Remember development and urbanization can cause urban sprawl. That pollution could be
air pollution, light pollution and heat pollution. We are trying to conserve our planet, preserving
it in national parks, wilderness areas, wildlife refuges and wetland areas. But the biggest
thing is we have to be smart in the growth. We are always going to have development, but
we have to make that smart development. And I hope that was helpful.