6. The Congo BasinPhoto: environment.nationalgeographic.com
The second largest rainforest in the world after the Amazon, the Congo Basin spans across six Central African countries. It is a collection of forests, rivers, swamps and savannas. It’s also responsible for 40% of the world’s oxygen. The United Nations has estimated that more than 2/3 of the forest and its plants and animals could disappear by 2040. Illegal logging, mining, ranching, farming, and guerrilla warfare are destroying the basin yearly.