Today I have a great guest-post by Jeremy Fordham, a writer who assesses and promotes virtual PhD programs. He is an engineer who hopes to inspire dialogue in unique niches by addressing topics at the intersection of many disciplines. A neat experiment illustrating how greenhouse gases in the atmosphere can trap heat follows a short discussion on the concept of “global warming.” Enjoy!

Lots of people today are talking about “sustainable living” and “green energy” as if they were the panaceas to all of the world’s climate problems, but it is not that simple. It is one thing to live in a way that keeps the environment healthy, but it’s another to actually understand why people think we need to live that way in the first place. And while the basic concepts behind sustainability might only seem accessible to scientists and people who have completed work in technical PhD programs, kids are actually well-equipped to understand the principles underlying the most complicated energy debates today.

At the heart of most sustainability issues is global warming, which describes a general upward trend in the Earth’s average temperatures. There is a lot of debate as to what causes global warming and whether or not it is just occurring naturally (the Earth is known to shift between extremely hot and extremely cold periods over time). One of the most prominent theories that describes this temperature rise is the greenhouse effect.

In a nutshell, certain byproducts of combustion collect in the Earth’s atmosphere in a type of blanket. In a normal world, much of the sunlight that strikes Earth’s surface should be reflected back into space, causing the Earth to cool. Instead, what actually happens is that this blanket of greenhouse gases (carbon dioxide, methane, water) absorbs the heat that should be sent back to space. Over time, this heat accumulates and causes general temperatures to go up on the Earth. This is called the greenhouse effect.

Many people believe that over-consumption of fossil fuels has significantly contributed to this increase in Earth’s temperatures. The following experiment demonstrates the greenhouse effect in a way that makes it easy for a child to understand what’s going on at a larger level with the planet.

What you’ll need:

2 medium-sized mason jars,
Water
4 ice cubes
A large Zip-Lock bag (large enough to cover and seal one of the jars completely)
Sunlight
A thermometer

What to do:

Fill each of the jars about ¾ full of water. Add 2 ice cubes to each jar, then seal one of the jars in the Zip-Lock bag. The sealed jar is the one that will produce the greenhouse effect.

Place both jars outside on a sunny day for at least two hours.

After the time is up, measure and record the temperature of the water in each jar.

The water that was in the jar with the Zip-Lock bag over it should be warmer. Why? The bag, much like greenhouse gases, trapped the heat that entered through the it from escaping. Sunlight that initially penetrates the Zip-Lock shield has a high energy and is able to move right through the material, but when it is absorbed by the water (and the jar) and radiated back, its energy is much lower—so low, in fact, that it cannot escape the bag. This causes the temperature inside the bag to increase much more than the water in the jar that is left open to the wind and sun. Effectively, this is what happens to the Earth.

It is important to teach kids that, while this process is a normal part of the Earth’s heating and cooling cycle, human activity indeed affects the concentration of greenhouse gases in the atmosphere. Exhaust from industrial activity and motors of all kinds regurgitates carbon dioxide into the air, contributing to the Earth’s temperatures.

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