There are two ways to reduce net emissions of carbon dioxide: limit how much carbon dioxide is emitted into the atmosphere as we burn fossil fuels, or increase the rate at which it is absorbed. In this lesson, discussion topics include the Kyoto Protocol and the use of carbon credits to reduce emissions of carbon dioxide into the atmosphere. Students can listen to a National Public Radio show that reports on new research that both illuminates and further complicates the picture of how the Earth is warming. The lesson includes an activity in which students examine their personal annual carbon emissions (calculated in the previous exercise) and determine how many trees it would take to sequester these emissions. They will then extrapolate this number to the populations of their school campus and their county.