Climate change is a significant shift, over a long period of time, in the statistical profile of weather patterns. For most of geologic history, natural factors—solar radiation, continental drift, oceanic circulation, volcanic activity—have forced these shifts. In the period since the late nineteenth century, anthropogenic global warming (AGW) displays the impact of industrial activity, largely through the concentration of greenhouse gases generated by the burning of fossil fuels. AGW can be seen as one component of the “Anthropocene,” an unofficial chronological term that acknowledges the significant influence of human behavior on the Earth’s ecosystems. Most scientists who favor the naming of this new geological era date its onset to the commencement of the Industrial Revolution, but some backdate it to the rise of agriculture, when humans began to transform land use and biodiversity on a large and global scale.