The Greenhouse Effect
The next time you eat pizza, save the box and line its inside bottom with tinfoil. Next, cut a large hole in the box’s lid, and cover the hole with cellophane. Then, put some tortilla chips topped with unmelted cheese in the box. Close, and place the box out in the sun next to an uncovered plate of cheese-topped chips.
What you’ll witness is this: the boxed cheese melts faster than the cheese on the plate. But why? After all, the uncovered plate is exposed directly to the sun.
What’s happening in the box is the greenhouse effect: light enters and reflects off the cheese, chips, and the foil. Instead of reflecting clear and away, however, some of the light rays are reflected back down into the box by the cellophane. This leads to warming, which is why the boxed cheese melts faster than the exposed cheese.
The greenhouse effect is, in a nutshell, what’s driving today’s warming (remember: over 1º average global temperature rise over the past 200 years). Greenhouse gases like carbon dioxide (think cellophane) absorb sunlight that would have otherwise been lost to space and reemit it, sometimes back towards Earth. More greenhouse gases equals an amplified greenhouse effect.