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. .