Pollution Greenhouse Effect (GCSE Chemistry)


Uploaded by freeeschool on 04.09.2012

Transcript:
GCSE Chemistry – Pollution Greenhouse Effect
Hello and welcome to a video about Pollution and today we are going to look at the Greenhouse
Effect and how it might lead to something called Global Warming.
Here, we have a diagram of planet Earth and surrounding planet Earth is the atmosphere
which is shown in this light blue color here. The atmosphere does a good job of keeping
the temperature of the Earth within certain extremes. It doesn’t get too hot and it
doesn’t get too cold and everything can work in cycles quite well within the temperatures.
The way this works is that heat energy comes in from the Sun and it gets either absorbed
by the surface of the Earth, but some of it gets reflected away. Enough is reflected away
so it doesn’t get too warm, but enough is absorbed so it doesn’t get too cold, either.
Now, what we tend to do as humans or the idea is that we are contributing to the increase
in this temperature by making the atmosphere absorb more of the heat than it receives.
It does this by a gas that is produced call Carbon dioxide.
Carbon dioxide does a good job of absorbing the heat that comes from the Sun. The more
carbon dioxide that is in the atmosphere, the more heat energy from the sun is absorbed
and that leads to a warming of the Earth’s temperature. It is worth mentioning that the
amount of CO2 in the atmosphere is only about 0.04%-0.03%, depending on where you look at
the source. But it is only a small amount of increase of just 100th of a percent can
be enough to have an impact on the temperature of the Earth.
Where is this CO2 coming from? The majority of it comes from power stations that burn
fossil fuels. Fossil fuels are also burned by cars. Petrol, which comes from crude oil,
is also fossil fuel. But those fossil fuels burned as fossil fuels produce CO2 which goes
off into the atmosphere. CO2, as we mentioned, is a good absorber of heat energy.
The more electricity we generate, the more fossil fuels we burn, the more vehicles we
use, the more CO2 that goes into the atmosphere and that has a bigger effect of absorbing
the temperature or absorbing the heat that comes from the sun. That leads to an overall
rise in the temperature and that, some scientists say, could lead to what we call “climate
change”. That’s an overall increase in the temperature of the Earth. It could lead
to flooding because of weather changes; it could lead to the melting of the ice caps
of the North Pole and South Pole. A lot of that over the recent years seems to be melting
away. This could be due to the rising temperature of the Earth.
There are lots of possibilities other than this that might happen and we can’t be absolutely
certain what sort of things are going to happen. But the idea is increasing the amount of CO2
is increasing the temperature of the Earth and it could lead to these various things.
It is worth mentioning one other gas that is produced that does also contribute to the
Greenhouse effect and that is gas called Methane. While that also contributes to the greenhouse
effect, it doesn’t have as much of an impact like the CO2 because there is not much of
it being produced. But methane, basically comes from the digestive system of cows when
they sort of pass wind, I guess, as reactions go on inside their guts that produces methane
and this is released into the atmosphere.
Here I have what is called a paddy field or rice field. The conditions on the rice field
are such that they also produce methane. This is a gas that is so often forgotten but it
does also contribute to the idea of global warming.
That’s an overview of the Greenhouse effect and Global warming and a few details that
you need to be aware of and make sure you know and remember. But apart from that, that’s
it for this video.
[end of audio 4:25] GCSE Chemistry – Pollution Greenhouse Effect
Page…1