REASONS / CAUSES OF EXTINCTION

 In this chapter we shall brush through some of the causes or reasons of extinction. In our next chapter however, we shall look at the human induced causes in depth. 

1. Habitat Loss 

The most common cause of endangerment is habitat loss. Plants and animals need space to live and energy provided by food, just as humans do. As human population and consumption increase, wildlife habitat is converted to houses and highways. Forests are cut down for building materials, fuel, and paper.

Even if habitat is not completely destroyed, it can be fragmented or degraded so much that it can no longer support the species it once did.

Many species, particularly large mammals, need large areas of habitat to survive and reproduce. Patches of forest or grassland surrounded by farms or cities, or divided by roads, will not support these species. 

2. Changes in the Atmosphere 

We know little about how changes in our atmosphere, such as global warming or ozone depletion, is affecting other life forms. However it is becoming more apparent every day that climate change is, and will have a significant impact on the planets species.

3. Diseases 

Disease and insect infestations, which are natural and nonthreatening phenomena in many ecosystems, can deal a death blow to populations weakened or depleted by other pressures.

4. Climatic Heating and Cooling

Climate Change is caused by a number of things. The effect that climate has on extinction is very big. The biodiverse Earth can't keep up with the rapid changes in temperature and climate. The species are not used to severe weather conditions and long seasons, or a changing chemical make-up of their surroundings. As more species die, it is only making it more difficult for the survivors to find food. The warmer climates we are used to present-day are perfect for diseases and epidemics to thrive.

5. Changes in the Sea levels of Currents 

The changes in sea levels and currents is a result, in part, of the melting freshwater. The denser, saltier water sinks and forms the currents that marine life depends on. Ocean floor spreading and rising also affects sea level. A small rise in the ocean floor can displace a lot of water onto land that is all ready occupied. The gases from the volcanic activity can also be absorbed by the water, thus changing the chemical composition, making it unsuitable for some life.

6. Asteroids/ Cosmic Radiation 

Asteroids hit the earth with extreme force. The reverberations can be felt around the world. The impact site is completely destroyed.

Cosmic Radiation is radiation being emitted from outer space and the Sun. It is hypothesized that being exposed to too much cosmic radiation can mutate genes, which can potentially weaken a species' genepool in the future. Since the radiation comes from space and the Sun, it is extremely difficult to avoid the radiation. Supernova remnants is one source of cosmic radiation.

7. Acid Rain 

Acid rain forms when sulfur dioxide and/or nitrogen oxides are put out into the atmosphere. The chemicals get absorbed by water droplets in the clouds, and eventually fall to the earth as acid precipitation. Acid rain increases the acidity of the soil which affects plant life. It can also disturb rivers and lakes to a possibly lethal level.