Humans Behind Sixth Period of Mass Extinction According to Studies

 

extinctionHumans are behind the sixth period of mass extinction that Earth is experiencing, according to a recent Stanford University, the University of California, Berkeley, and Princeton University study and a second study, both published this past week. Also, humans might become one of the species to become extinct, relatively early on, the creators of our own demise.

The authors of the first study believe that they are being very “conservative” with their analysis, and have stated that in as little as three more generations, if the current rate which animals are becoming extinct continues, human populations will be significantly effected. The study was published in the journal Science Advances on Friday.

Earth is now well into its sixth period of mass extinctions, the worst one since the dinosaurs became extinct, assert the authors of the Stanford study. The rate that animals are becoming extinct is 114 times what is considered to be “normal.” The study, in large part, blames humans for the rapid increase. Humans have been blamed by many scientists for three of the reasons behind the current period of mass extinctions, which are climate change, habitat loss and pollution.

The time that humans have left to try to halt the sixth period of mass extinctions, or at least slow it down, is getting shorter and shorter, if the authors of the study are correct. They assert that as a result of the damage to the planet that has already occurred, it might take millions of years for Earth’s bio-systems to make a recovery.

The sixth period has been going on for approximately 115 years already. During the past 115 years, the study affirms, the numbers of animals becoming extinct has greatly increased. More than 400 species with backbones have become extinct than what could be attributed to causes other than human involvement in the extinctions.

One of the lead authors of the Stanford University study, Dr Gerardo Ceballos, from the Universidad Autonoma de Mexico, wrote that if the rate of extinctions continues, “our species itself would likely disappear early on.” Already, the study states, 41 percent of all species of amphibians are in danger of becoming extinct. Also, 26 percent of all species of mammals are in danger of facing extinction during this sixth period of mass extinctions.

A few of the species that have become extinct already include China’s baiji river dolphin, the Tasmanian tiger, and the California grizzly bear. An article at the Live Science web site states that a few other animals on the brink of extinction include the Sumatran rhinoceros, the Western gray whale, the red wolf, and the Siberian tiger. The Costa Rica golden toad and the Yangtze dolphin are two other species which are on the verge of becoming extinct.

A second study, in which one of the researchers and authors of the Stanford sturdy was involved in writing, University of California at Berkeley’s Anthony Barnosky, was published last week, as well. It attempted to analyze and prove what is so different and unique about the current sixth period of massive extinctions.

Paleontologist Mark Williams, of the University of Leicester, was the lead author of this second study. The researchers discovered that none of the causes believed to be behind the past five mass extinctions is behind the sixth period, which is still in its early stages. The reasons behind the other periods included major asteroid impacts, massive volcanic activity, and rapid climate change. Though humans are believed by many scientists to be one reason behind the on-going climate changes now, the effects so far are not as rapid as during times of past extinctions.

Humans are behind this sixth period, this second study also affirms. One of the main causes that the study mentions is hyper-fertilization. Using the Haber-Bosch process, humans extract millions of tons of nitrogen from the atmosphere and also obtain an approximately equal amount of phosphate from the earth. This nitrogen and phosphate is used to fed crops and nourish farm animals, which humans then consume. The second study asserts that this hyper-fertilization has led to the mass extinction of many other organisms.

Also, humans have helped contribute to the sixth period of mass extinctions by our rapid expansion as a species. Humans now make up, according to calculations done by scientist Vaclav Smil, of the University of Manitoba, a third of the vertebrates living on the land. The majority of the other two-thirds of the vertebrate land species are composed of the animals humans love to eat the most, like sheep, goats, pigs, chickens and cows. That has crowded the remaining vertebrate species of wild animals, like lions, bears, giraffes, tigers and elephants onto the fringes of land left, which accounts for around 5 percent of the land.

Another human-driven factor in the sixth period of mass extinctions is the breeding and genetic modification of animals by humans. Also, the energy that humans obtain from the ground to fuel our machines, in the form of hydrocarbons, has had a negative effect on the environment, according to the second study.

Humans are behind the sixth period of mass extinctions that is now in its early stages, according to these two studies. While there is still time to change the current rate that species are dying out, the time frame is getting shorter. The studies both assert that humans might become the engineers of our own demise, beginning within three generations, if enough is not done to halt the current rate at which species are becoming extinct.

Written and Edited By Douglas Cobb

Sources:
Sky News Australia: Humans under threat in new mass extinction
Dawn.com: Earth entering sixth mass extinction phase: study
The Guardian: The Earth stands on the brink of its sixth
mass extinction and the fault is ours
Live Science: 10 Species You Can Kiss Goodbye
Photo Courtesy of n.karim’s Flickr Page – Creative Commons 2.0

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