This chapter deals with international boundary disputes and natural resources. After providing an historical context to modern boundaries, the chapter describes how climate change directly impacts land, food, and water access because of increased extreme weather conditions. Thus, climate change can threaten peace and security in fragile regions due to conflicts over diminishing inhabitable territory and natural resources. The chapter assesses how international boundary disputes can be affected by changing demands for oil (eg in Kurdistan and South Sudan), and for renewable energy resources (eg the ownership, use, and control of rivers crossing multiple borders). It also reflects on a more global scope the effects that climate change-related migration has on the modern understanding of international borders.