Eventual Sixth Extinction Threatens Earth

Researchers Identify Human Activity as Main Threat to Species


NASA Photo


66 million years ago a meteor hit the Earth. According to a 2011 nationalgeographic.org article this caused roughly 75% of species to die out. This was the fifth mass extinction in Earth’s history. Scientists say the sixth is happening right now. For years, animals have been dying at an alarming rate. They have died for many reasons but humans seem to be the main cause. From climate change to acid deposition in forests animals have been going completely extinct due to human activities. According to nationalgeographic.org, scientists are calling it “the Holocene extinction” or the sixth mass extinction.

National Geographic goes on to say the two main causes of extinction or endangerment are habitat loss and loss of genetic variation. Habitat loss is when a species loses its range to hunt or loses its home, usually due to human deforestation for things such as timber, agriculture and construction.

Each and every species is classified under “The Red List of Threatened Species.” The Red List is a list that keeps track of the state of all species and classifies them based on the species’ range, population, and habitat. There are seven categories they can be placed in. These categories are as follows: least concern, near threatened, vulnerable, endangered, critically-endangered, extinct in the wild, and extinct.

A Princeton.edu article suggests that the amount of extinctions per year is a heavily debated subject. Estimates range from a few thousand to 100,000 species completely extinct every year. In history, there have been five mass global extinctions in which 50%-95% of species went extinct. These events were the Ordovician, Devonian, Permian, Triassic, and Cretaceous extinctions, with the most severe being the Permian in which 95% percent of all living species went completely extinct. The most commonly known of them is the Cretaceous when a meteor struck the earth marking the end of the reign of the dinosaurs.

The Holocene or Anthropocene extinction is the sixth mass extinction going on as we speak due to human activities. It is thought that most species going extinct are left undocumented. This means that species are going extinct faster than we can even discover them. Humanity has been regarded by scientists as a “global super predator” that preys on even the strongest of apex predators. This current extinction started at the end of the Ice Age when species such as the Wooly Mammoth, Saber Tooth Tiger, and the Giant Ground Sloth died out because of human overhunting.

This mass extinction is causing massive loss in global biodiversity. University of Michigan researchers (umich.edu) say that loss in biodiversity is said to be having negative effects that rival even climate change and pollution. When 21-40% of an ecosystem’s species have gone extinct, the effect on the ecosystem is comparable to climate warming. When an ecosystem loses 41-60% of species the effects are comparable to ozone pollution, acid deposition, and nutrient pollution.