Carbon is the chemical backbone of life on Earth. Carbon compounds regulate the earth's temperature, form the food that nourishes us, and provide the energy that powers our global economy. Most of the carbon on earth is stored in rocks and sediments. The rest is in the ocean, in the atmosphere, and in living organisms. These are the reservoirs through which carbon cycles are conducted. Human activities have an enormous impact on the carbon cycle. The carbon footprint measures the impact of human activities on greenhouse gases (GHG). Specifically, carbon dioxide, or CO2, released by burning fossil fuels (coal, gasoline) to produce and meet all of our consumption needs.