Digital Earth is a next-generation global database to visualize various information on the earth seamlessly. Now we are facing a lot of serious global issues. Especially environmental problem is an urgent concern for human beings to cope with. To manage this crisis of our environment as global commons, we need to identify and monitor the phenomena which occur on the surface of the Earth and save them as data to be analyzed. The cyber space re-assembled and visualized based on this huge geospatial information, we call it Digital Earth. In this lecture, we explore the possibility and prospect of this new technology for environment management.