On the Brink focuses on case studies that link armed conflict and political crises with environmental issues such as the loss of grasslands, spreading disease, deforestation, soil erosion, water scarcities, surging populations and global climate change. The program features the work of scientists, community organizers and political leaders, as they grapple with the fact that the world's political security may be bound up with the quality of the land, air and water.

In this episode of Journey to Planet Earth, we travel to India/Bangladesh, South Africa, Peru, Haiti, Mexico and the United States. For American audiences, it is particularly important to understand that struggles over natural resources can lead to instability in regions critical to the well being of the West.