Is the Thermostat Broken?
The greenhouse effect is a naturally occurring phenomenon, but human actions are still to blame for current global warming.
How is this possible? Think about living in a house.
Why do people live in houses? We could just live in wide open fields, right? Well, a house with a roof and walls provides us with shelter and privacy, but it also keeps us warm.
It may be no surprise that the warmth we feel from living in a house does not come from the walls themselves. It comes from some heating device that we put in the house such as an electric heater or a wood stove. The walls simply keep heat from escaping to the surrounding air. Not all of the heat, however, is contained within the house. Some of it does escape requiring us to add more heat as it cools. If too much heat is escaping, our heater will need to work extra hard since it needs to keep replacing what was lost. This uses a lot of energy.
To use less heat (and energy), we may consider putting more insulation in the walls. Since insulating materials are good at trapping heat, this will keep more warmth close to the source. We could therefore use the heater less often which requires less energy, while keeping the temperature in our house at the same comfortable level. However, if we keep using the heater the same way as before, the temperature inside our house will rise.
“If we add insulation to the walls and keep the heater running, the temperature in our house will rise. ”
In this analogy, the original walls are the naturally occurring greenhouse gases in our atmosphere, the added insulation is the equivalent to greenhouse gases added by people, and the heater represents the earth. Why is the heater not representative of the sun? While energy originates from the sun, most solar radiation passes right through our atmosphere, warming the surface of the earth. Our air is then heated from below by the earth.
“The sun heats the surface of the earth, which in turn heats the atmosphere.”
Just like the walls of our house, greenhouse gases absorb energy emitted by the earth's warm surface. This keeps some of the heat from escaping into space. If our house didn’t have walls, it may be too cold to live in, and if our planet was not blanketed with greenhouse gases, the average temperature would be well below freezing. Naturally occurring greenhouse gases keep our planet at a comfortable temperature, one to which all living things have adapted. They are definitely a good thing.
By burning fossil fuels, however, we are increasing the amount of greenhouse gases in our atmosphere which is like adding insulation to our house. One such greenhouse gas is carbon dioxide or CO2.
While our energy source is not changing, we are adding insulation to our atmosphere by adding more greenhouse gases. The result? Global warming.
Importantly, our house analogy differs from climate change in the following way: In the real world, we cannot change the setting on our heater. The amount of solar radiation that is entering our atmosphere and warming the earth is the same as it was before (same old heater), but we are adding greenhouse gases to our atmosphere at an unprecedented rate (continuous and increasing flow of insulation into our home).