Carbon Dioxide and the Greenhouse Effect

In this experiment, we will
show the role of carbon dioxide in the greenhouse effect. Carbon dioxide is
one of the gases that absorbs Earth’s heat,
or thermal radiation. In this experiment, we
will show a carbon dioxide absorbing thermal radiation, and
so mimic the greenhouse effect. So what is the
greenhouse effect? Well, let’s begin with
the earth, its atmosphere, and the sun. The sun emits energy out into
space, called solar energy. When the solar energy reaches
Earth, two things happen. Some solar energy is reflected
by the top of clouds, ice sheets, and
other shiny surfaces, but most of the
solar energy passes through the Earth’s
atmosphere and heats up the surface of the Earth. As the Earth warms up,
it releases heat up into the atmosphere. This heat is called
thermal radiation. Some of this thermal radiation
escapes out of the atmosphere, and goes into space. However, there are certain
gases in the atmosphere, called greenhouse
gases, which absorb and trap the Earth’s heat
inside the atmosphere. These greenhouse gases
or, GHGs, are primarily water vapor, carbon dioxide,
methane, nitrous oxide, and ozone. This keeps the surface
of the Earth warm. In fact, if we didn’t
have the atmosphere, the Earth’s average temperature
would be closer to 0 degrees Fahrenheit, as opposed to its
current average temperature of around 57 degrees Fahrenheit. So the greenhouse effect
is a vital process that sustains life as
you know it on the Earth. We’re going to need three
things to do this experiment. Firstly, we’re going to be a
source of thermal radiation, and we can use a candle. You can feel the thermal
radiation, or heat, when you hold you hand next
to the flame of a candle. So secondly, what we
need is a sensor that can detect thermal radiation. What we will use is
an electronic device called a thermopile. You can see that we
built a little copper chamber around the thermopile. There’s a thin film
or plastic at the end of the sensor, which is
just to stop the gas blowing into the candle. We are going to
introduce different gases into this space, and
see how the gas changes the thermal radiation
from the candle that reaches the thermopile. The third thing that we
need is carbon dioxide gas. We will make this by mixing
baking soda and vinegar. OK, let’s try this. Here we have the green
balloon with air in it. And we’re going to
open this first valve. And then we’ll open the
valve to the chamber. And as expected,
nothing happens. The line stays steady. And now here we have
the red balloon, that’s the one with the CO2 in it. So we’ll open the
valve to the balloon, open the valve to the chamber. And again, as we
expected, the line goes down because
the carbon dioxide is absorbing some of the thermal
radiation from the candle. What this experiment shows
is that carbon dioxide is a greenhouse
gas, and contributes to keeping the surface of
the Earth warm by absorbing thermal radiation. Therefore, if we introduce
larger quantities of carbon dioxide into the atmosphere,
we expect the atmosphere to warm, and cause
global climate change.

Comments 13

  • Great explanation thanks.

  • Hey great video. You may have wanted to mention a few key points.
    1-green house gases make up 1% of the earth's atmosphere
    2- out of that 1% that is green house gases, 95% of those gases are water vapor
    3- out of the 5% of the green house gases, CO2 makes up 1%
    4- out of the 1% of CO2, 1/20th of that is man made.
    This is to say that if the whole world stopped using all current energy and all methods of transportation, for 10 years, the effect on green house gases would not be measurable.
    Should we look at non fossil fuel alternatives and change our way of living, to better the world, of coarse. Will one sided funded science and a complete media black out on accurate science do this, no! You have to ask yourself the reasons behind why they are doing this! When they have to start saying, the reason why it's colder is a byproduct of global warming, or are you going to believe what you see and feel, or what I say, shouldn't you start getting some facts? The real information is out there, you just have to look.
    Atmosphere=1% green house gases-5% of that is CO2, 1/20th of that is man made,  and the US stops all CO2 production which is impossible, no change.
    Let us not forget, WE, give off CO2, and plants need it to life.
    By the way, polar bear population in Eastern Canada has reached an over population to the point that, consideration is being give to culling, (killing off) to get the numbers down to prevent a mass outbreak that would decimate the population. You don't see that on the news, weird??? 

  • Another good example is using spectra. YOu basically shine a focused bright light through a prism so you get a rainbow shining out onto a piece of cardboard. Then as you blow CO2 into it you'll start seeing black bands form in the rainbow (Although most of the absorbsion is in the infra-red which isn't visible to the human eye. Some brands of domestic video camera however can see IR, notably sony in nightvision mode). These are called "absorbsion lines" and indicate that at certain frequencies the gas intercepts photons, and since energy can't be created or destroyed it means its transformed, into heat (and to some extent kinetic energy)

  • from this demonstration one could conclude that air does not have a greenhouse effect. wish you did some quantifying.

  • nice videos..wat are the frequency absorbed by the co2 molecule. and with 0.04 % in atmosphere what is the likelihood of reflected radiation is encountered by a co2 molecule and it gets heated…

  • The CO2 blocks infrared radiation from reaching the earth's surface. You forgot to mention this.

  • Recently, a family friend tried arguing against global warming being real based on her discrediting Al Gore. My response was that a 10 minute lab demonstration in an 8th grade Earth Science classroom would show that the Greenhouse Effect is real (with the implication that this demonstrates that global warming is real since all greenhouse gases levels are increasing).

  • If you want to see a demonstration as to why greenhouse effect is false see the video on my channel.

  • Fatally flawed, right from when the candle appeared. The candle produces shortwave infrared radiation identical to that from the Sun, which is NOT involved in the atmospheric "greenhouse effect".
    And this comes from MIT??

  • Co2 is still just 0,04 of the atmosphere. So I dont think it is possible to measure this mechanism in earths climate. Water vapor however is 99% of atmosphere…

  • Whats wrong with this video? The atmosphere starts at the surface of the planet and it's density decreases with altitude – it is NOT a reflective layer that resides on the edge of space!


  • What you have proved that is a change from 0ppm to 1000000ppm or 100% CO2 does have an affect! Great But you forget to mention that all life will be dead at 8000 ppm. And besides that you proved it for the wrong wavelength. But I guess you have no clue of what I am talking about! This is not even science – this is pure stupidity!

  • Links to Some Short ‘YouTube Videos’ Describing and Demonstrating the Greenhouse Effect:
    [Though having a workable and understandable definition for the cause of enhanced global warming is helpful, the following short video lessons’ descriptions and demonstrations are essential supplementals.
    First though, my simple definition:
    “As shortwave visible sunlight strikes the surface of the Earth, that which is not reflected back into space is absorbed and converted into long wave ‘infrared radiation’ and radiated away into the atmosphere where it interacts with large moleculed trace gases such as carbon dioxide. This slows down the escape of heat into space and results in higher atmospheric temperatures.”]
    Videos Describing —
    CO2 and the Greenhouse Effect
    (8 minutes):

    How Greenhouse Gases Warm the Earth (4 minutes):

    How Burning Fossil Fuels Leads to Climate Change (5 minutes):

    Greenhouse Gases: Climate Change
    (1 1/2 minutes):

    How Do Greenhouse Gases Actually Work? (3 minutes):

    Videos Demonstrating —
    Greenhouse Gas Demo (4 minute):

    “Mythbusters tests global warming theory- does CO2 warm air?”
    (3 minutes):

    “Why Is Atmosphere Warming” —greenhouse gases (5 minutes):

    “Carbon Dioxide Trapping of Earth's Heat – A Laboratory Experiment”
    (2 minutes) Lab Demo starts at one minute mark:

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