Many scientists believe that carbon dioxide (CO2) emissions are causing the earth's temperature to slowly rise, in a phenomenon called global warming. In the last century, CO2 levels in the atmosphere have risen 28%, and the atmosphere has warmed by almost one degree Fahrenheit. That may not sound like much, but during the last ice age, the Earth was only 5 to 7 degrees cooler!

Carbon dioxide is released into the atmosphere when fossil fuels (coal, oil and natural gas), or their byproducts (like gasoline) are burned. This CO2 acts like the glass windows in a greenhouse, letting light and heat in, then trapping the heat inside.

One way to help counteract carbon dioxide emissions is to plant trees. Trees absorb CO2 from the air, and use it during the process of photosynthesis. During photosynthesis, CO2 is chemically broken down into oxygen, which is released into the atmosphere, and carbon, which is stored, or sequestered, in the tree's trunk, branches and roots. According to estimates by American Forests, one tree will sequester over 600 pounds of carbon over a 40-year period.