Carbon dioxide (CO2) and global warming
The hypothesis that a higher concentration of carbon dioxide in the air will slow down the rate at which the temperature of the air falls, is proven to be true. The heat released by the soil in the tank is captured by the carbon dioxide molecules. Some of the energy is returned to the soil and some of it is released out of the tank. Since the tank with the car exhaust gas had the highest concentration of carbon dioxide molecules, it demonstrated the slowest rate of cooling down.
The increase in carbon dioxide levels in the atmosphere has led to an increase in global temperatures. It is causing significant changes to weather patterns, the melting of polar ice (glaciers), and the rising of sea levels, causing islands to disappear. Furthermore, the increase in ocean temperatures has led to to the extinction of certain species of marine life.
The experiment can also be repeated using water to replace the soil in the tank.
Try to perform this experiment by using a hair dryer to obtain a higher starting temperature. Observe the difference in the rate of cooling.
Be wary of carbon monoxide poisoning from the exhaust of the car. Conduct the experiment in a well ventilated garage. Adult assistance is required for the operation of the car.