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.