We use energy in everyday activities, from turning on the lights to driving to school. Most of that energy is derived from burning fossil fuels, which release greenhouse gases (GHGs), such as carbon dioxide (CO2), into the atmosphere. A carbon footprint is the total amount of GHG emissions caused directly and indirectly by an individual, organization, event, or product. A households carbon footprint varies depending on factors such as home size, types of vehicles used, and household members eating and purchasing patterns. We care about our carbon footprint because GHGs absorb energy and trap heat in our atmosphere. We need some amount of GHGs in our atmosphere to survive, but too great an amount and too rapid an increase can have devastating effects on our environment, our health, and the economy. Current consumption of fossil fuel releases more than 25 billion tons of CO2 into the atmosphere every year. If current trends continue, atmospheric CO2 will triple by the end of the centurylevels not seen for more than 40 million years. By measuring our carbon footprint, we can learn how we are contributing to this rise in atmospheric CO2 and how we might use energy more efficiently. In this lab, you will calculate your households yearly carbon footprint. After calculating your data, you will draw observations about your households carbon footprint, including identifying ways you can work to reduce it.