This lecture will go over the basic principles of satellite-based optical remote sensing, spectral indexing and image classification, with a particular focus on land cover change. Through practical examples on the google earth engine platform (please sign up here https://earthengine.google.com/ at least 5 days before the class), we will see how remote sensing can be leveraged to monitor and attribute environmental change in physically inaccessible regions. We will finally discuss the potential and limitation in combining remote sensing and social sensing to monitor and understand coupled human natural systems.