Over 65 million years ago, dinosaurs roamed this earth, yet their peaceful harmony ended when a meteor struck, creating a crater in the Yucatan Peninsula and bringing about a drastic fluctuation in climate as well as the extinction of the species. Just as climate change led to the extinction of the dinosaurs, current climate change is accelerating the progress of the current Holocene extinction.

The Holocene extinction, also referred to as the sixth extinction, is the current mass extinction of numerous species. The sixth mass extinction also is the first caused by humans.

The Holocene extinction is said to have begun approximately 12,000 years ago with the extinction of the Cuvieronius and continues through the 21st century.

Researchers predict that in two generations’ time, 75 percent of known species will be extinct.

Generally, 2 out of 10,000 species go extinct over 100 years due to natural changes in the environment; as the Holocene extinction becomes more evident, around 477 species have been wiped out since 1900.

While previous mass extinctions were caused by natural disasters, scientists believe that the Holocene extinction started due to damage to the environment caused by humans.

“If you look back 10,000 years, there are quite a few megafauna, big species, that have gone extinct, and that directly matches when humans first arrived,” biology teacher Kate Schafer said. “There’s kind of this myth that people in the past lived in harmony with nature, and they knew when to stop hunting, but we’re accumulating more and more evidence that suggests that when given the opportunity, just like other organisms, we exploit resources to their nth degree, and that sometime leads to extinctions.”

Recent increases in instances of climate change, deforestation and poaching all contribute to the sixth extinction. The impacts of the last two centuries have led to more species becoming extinct than any others from the past 12,000 years.

“I think that we have yet to see the effect that we’re going to with regards to climate change. Of course, we already have seen significant warming occur, but the large number of extinctions that we’re likely to see in the face of climate change are yet to come,” Schafer said. “Most of the documented extinctions that we’ve seen so far have been due to one of a handful of factors. Habitat loss is a huge one; converting unaffected lands into crop land, [and] deforestation would be lumped into habitat loss.”

Human activity has heavily expedited the extinction of animal species in the sixth mass extinction. Human migration has led to the introduction of invasive pests, both plant and animal, which result in extinctions of local species.The spread of pests and disease have also led to local groups of humans being wiped out.

Breeding domesticated animals has also led to an uneven distribution among different species. According to BBC News, humans and domesticated animals outweigh wild vertebrates by 95 to 5. At the beginning of the Holocene epoch, this combined weight was less than 0.1 percent of what it is now.

An analysis by the World Wildlife Fund (WWF) and the Zoological Society of London (ZSL) suggest that 3,706 species from around the world exhibited a 58 percent decrease in quantity from 1970 to 2012.

Methods are being proposed in the scientific community to slow down the extinction process. The process of re-wilding involves introducing a species that rarely survives in a region to another habitat where it used to live but ceased to due to the effects of invasive species.

Other methods involve trying to bring species that are extinct back through in-vitro fertilization with similar species, cloning from a frozen cell, and sequencing DNA from fossils to create artificial chromosomes, genetically engineer a cell, and clone it.

“I worked at the San Diego zoo, which is called the frozen zoo, in a lab full of giant cell lines of endangered species. The idea is cloning back some of these animals. The fundamental problems remain that we don’t have cell lines for that many animals,” biology teacher Mike Pistacchi said. “Even if we clone them back, the population is very small, and we have a very inbred population. I think the nervousness around things like the frozen zoo comes from the fact that people will say ‘It’s okay that they’re extinct in the wild, we’ll just clone them back.’ Reviving an extinct or extremely endangered species is an absolute worse case scenario.”

Prior to the the sixth mass extinction, the fifth major extinction, also known as the Cretaceous-Tertiary extinction, occurred sixty-six million years ago, causing species of dinosaurs to disappear. According to CNN News, natural disasters, such as volcanic eruptions and meteors, caused this extinction, eradicating approximately 95 percent of the species living on Earth. Seventy-five percent of all species at the time were wiped out during the extinction.
Previous mass extinctions include the Ordovician-Silurian extinction, the late Devonian extinction, the Permian-Triassic extinction, and the Triassic-Jurassic extinction. During each extinction, between 60 to 80 percent of all species at the respective times were wiped out.