Living things face a constant barrage of external stresses or threats that challenge their ability to survive and reproduce. If a species is unable to successfully cope with these threats through adaptation, they may face extinction.
A constantly changing physical environment requires organisms to adapt to new temperatures, climates, and atmospheric conditions. Living things must also deal with unexpected events such as volcanic eruptions, earthquakes, meteor strikes, fires, and hurricanes.
As new lifeforms arise and interact, species are further challenged to adapt to one another to deal with competition, predation, parasitism, disease, and other complex biotic processes.
In recent evolutionary history, threats facing many animals and other organisms have been driven primarily by the effects of a single species: humans. The extent to which humans have altered this planet has affected countless species and has initiated extinctions on such a vast scale that many scientists believe we are now experiencing a mass extinction (the sixth mass extinction in the history of life on earth).
Since man is indeed part of nature, man-made threats are merely a subset of natural threats. But unlike other natural threats, man-made threats are threats that we can prevent by changing our behavior.
As humans, we have a unique ability to understand the consequences of our actions, both present, and past. We are capable of learning more about the effects our actions have on the world around us and how changes in those actions could help to alter future events. By examining how human activities have adversely impacted life on earth, we can take steps to reverse past damages and prevent future damage.
The Types of Man-Made Threats
Man-made threats can be classified into the following general categories:
- Habitat Destruction & Fragmentation - The destruction or splitting up of once continuous habitat to enable humans to use the land for agriculture, development of towns and cities, construction of dams, or other purposes.
- Climate Change - Human activities such as the burning of fossil fuels, have altered the Earth's atmosphere and have resulted in global climate changes.
- Introduction of Exotic Species - Accidental and intentional introduction of non-native species into regions never before occupied by the species have resulted in the extinction of numerous endemic species.
- Pollution - Pollutants (pesticides, herbicides, etc.) released into the environment are ingested by a wide variety of organisms.
- Over-Exploitation of Resources - Exploitation of wild populations for food has resulted in population crashes (over-fishing, for example).
- Hunting, Poaching, Illegal Trade of Endangered Species - Some endangered species are targeted for their value on illegal markets.
- Accidental Deaths - Car hits, window collisions (birds), collisions with ships (whales).