Apart from the unidirectional arrows linking the innermost oval("Human population & consumption") to the surrounding zone of human activities, all connections between adjacent rings and segments are bidirectional. These links express the intrinsic interconnectedness and feedbacks among the various human activities and the natural processes.

These impacts include transformations of the land surface, the local extinctions of populations ("biotic losses"), the introduction of non-native species ("biotic additions"), and changes in the cycling of water, nutrients, and other chemicals. These processes, in various combinations, then cause changes in global climate patterns and irreversible losses in overall biological diversity.

In turn, because all these processes are inherently linked, changes in global climates and losses of biological diversity affect cycling processes in ecosystems, population extinction and introduction dynamics, and patterns of land transformation. In short, human environmental impacts are profound, pervasive, and to a large extent, self-perpetuating.

Most extinctions probably occur from a combination of these human factors - assisted by natural processes. For example, a population of organisms that has been decimated by habitat destruction and weakened by chronic low levels of pollution may be more susceptible to being completely eliminated when disease or extreme environmental conditions are present.

Because of the extensive habitat loss that has already occurred worldwide, scientists estimate that tens of thousands of species are headed for certain extinction over the coming decades, with no preventive action possible. Many other species will not go completely extinct, but will experience drastic population declines, lose distinct populations, and suffer severe loss of genetic diversity.

The cumulative result will be a world with significantly less biological diversity and less stable and resilient communities and ecosystems.