Throughout history, a leading cause of war has been conflict over resources. As the global population continues to grow, the increasing consumption of and demand for vital resources can generate crises of scarcity, poverty, and inequality, which can in turn lead to violence within, between, and among states. Resource scarcity and inequality of resources such as water, food, medicine, and energy can produce consequences at the local and global level. Worldwide impacts include environmental degradation, mass migrations, pandemics and war.