Limiting our carbon footprint requires not only a conscious effort to conserve energy and discover alternative fuel sources, but also a greater understanding of how humans have served as a significant catalyst in global climate change. Here are a few leading causes that humans have contributed to:

• Transportation If only we had listened to the Jetsons sooner. The EPA attributes nearly two-thirds of carbon emissions to automobiles and trucks since 1990, and nearly 20 percent annually. Exhaust contrails from airplanes contribute 2-3 percent of carbon emissions annually, making U.S. transportation as significant factor in recent climate change studies.
• Landfills Humans dump a ton of trash, which is nothing shocking. What most of us probably don't realize is that methane is produced as landfills gradually decompose, producing 34 percent of all methane emissions. Methane is particularly harmful—even though its concentration in the atmosphere is far lower than other gases—because it is capable of trapping more heat than other greenhouse gases.
• Deforestation Ever since Fern Gully, the push for saving global rain forest populations has been at the forefront for environmentalists. More than 34 million acres are burned each year, which throws the carbon dioxide balance off that is normally maintained through photosynthesis.

What is more disturbing is the ongoing debate over how much impact humans have had on global warming. The above examples are only a few factors, but it remains to be seen whether global warming science will lead people to adopt wholesale changes for a greener tomorrow.