The heating and cooling of the earth, changes in sea level, asteroids, acid rain and diseases can all be natural factors that cause a species to become extinct. Humans can also be the cause of extinction for certain species.
When a species cannot adapt to changing conditions, such as changing temperatures, they will not be able to survive. This inability to survive will hinder the repopulation of their species and will eventually lead to extinction. Many species also cannot adjust to changing sea levels and the effects that higher sea levels have on the environment. High sea levels not only change the way that species function in the ocean, but also alter the environments that are within the ocean.
Humans are one of the biggest non-natural threats to species and their rates of survival. Humans are responsible for overpopulating the earth with their species. Humans are also responsible for deforestation and air pollution that can be detrimental to many different species. Humans also use other species for their survival, such as the use of meat from animals. Hunting for survival, in combination with other human factors and natural causes, can result in the extinction of many different species.