Background extinctions are a naturally occuring (and important) development within the economy of nature. There are a number of reasons for a species’ population to come to an end organically. A lack of genetic diversity following a vicariance event makes them vulnerable as they may not be able to evolve in accordance to the changing environments around them. An influx of inbreeding will have greater effect on genetic variation. Perhaps habitat deterioration makes an environment no longer livable, reducing and fragmenting populations that have difficulty with far dispersal. Environmental conditions are subject to change and may do so too quickly, working against certain organisms. Epidemics spread, competition is inevitable. If too many of these variables come into effect at once, it could be detrimental for the survival of entire ecosystems. Background extinction is somewhat regulated by the environment to keep ecosystems at an equilibrium.
A mass extinction, on the other hand, is characterized as a geologically short interval of time in which at least three quarters of all life on Earth is lost. These mass extinctions are not commonplace, having only occured five times since the beginning of complex life on Earth, but it has been stipulated that the planet’s sixth mass extinction is underway. The ecosystem works similarly to a power grid; the worst damage rarely comes from the initial shock, but, rather, through a trickle down effect that ignites a number of failures down the line as a result of the loss of power. The effectively leads to a system collapse. The problem may be a the disappearance of a few species, but the interactions that others are designed to have with this one species is felt all over that particular ecosystem. All parts are somehow interconnected and therefore impacted in a way. This can happen through relationships like prey/predator or possibly through a symbiotic partnership that formed through direct co-evolution.
Contrary to the workings of background extinction, mass extinctions have too many of these smaller extinctions with drives system failures, resulting in life or death scenarios for many others down the chain. A good example of this would be the dependance that many species have on bees. Anthropogenic impact on the environment becomes more extensive and injurious each year, outcompeting the natural ecological processes and causing severe damage to the habitats and resources that were once supportive of a mosaic collection of plants and animals. As the basic survival tools once depended on by an array of species becomes unavailable, the longevity of many forms of biota is compromised. This hurt is felt all over the globe, a force so strong that it causes an irreversible fracture in the evolutionary line.
A sweeping extinction of majority of terrestrial biodiversity takes place. As a result of this, many scientists have taken up the term “Anthropocene” and have presented it to be the newest epoch. It is predicted that during this new epoch, Earth will experience a grand fall of biodiversity at the hand of humankind, the most dominant geological force. Until now, no known species has ever significantly decreased the biological diversity across the planet (Cafaro, 2015). The Secretariat of the Convention on Biological Diversity estimates that within the next one or two hundred years, humanity could eliminate one out of every three species. In an article by Philip Cafaro, professor of philosophy at Colorado State University, he discusses the three plausible ways in which to view the sixth mass extinction; as a loss of important resources, as an interspecies genocide, as a form of evidence confirming that the human species is a cancer on the biosphere (Cafaro, 2015).
These three approaches bring meaning to the idea of a new mass extinction and points in the direction of how Cafaro believes this situation should be responded to. The Holocene is the last great geological epoch the world has seen. During this time, the influence of man on his surroundings developed into a great morphological and geological power. Humans have been modifying natural landscapes ever since the beginning of this epoch, which started around 11,500 years ago following the last ice age. People developed the ability to change their local environments, but this power was limited to their immediate spaces. Agriculture and animal domestication was utilized, forests were converted into farmers’ fields, the concentration of people in certain territories led to the construction and rise of cities.
As a result of some of the technological advancements made at the start of the industrial period, humans were able to extend this reach much further. The steam engine was invented in 1748, and it was not long after that the great Industrial Revolution was in full swing. People all over the map now had new access to goods and wealth by newly booming economics, and commodity production and consumption was revered. The profound, systematic effect humans were having upon the planet rapidly grew stronger and became truly global following the end of World War II. Human-wrought impact steered away from exclusively local alterations and it is argued that currently this impact resembles that of significant past geological transformations, such as the retirement of one epoch as a contemporary one takes its place.
This new epoch is commonly known as the Anthropocene. The term “Anthropocene” was coined by a Nobel laureate named Paul Crutzen. Crutzen is a Dutch atmospheric chemist renowned for the work he has done on the science of climate change. In 2002, he wrote an article that was published in Nature arguing that the level of anthropogenically induced changes that have been made to the planet thus far have effectively moved Earth out of the Holocene stage. The epoch that is to follow has much less climate stability due to human activity. His approach quickly took hold, and the term has been taken up by scientists around the world. The phrase has also been used to potentially signify the start of the sixth mass extinction, but whether or not this mass extinction has yet come into effect is currently in debate. Those who believe that the sixth mass extinction has not yet started may claim that viewing the vast array of conservation concerns through the lense of extinction is simplistic.
The idea that earth has already entered the sixth mass extinction would imply that the entire field of conservation biology is useless, simply an effort to save our house as it is already in the process of imploding. Many who disagree with a current mass extinction are at a disagreeance about what point it should be declared at. Critics believe that in the midst of a mass extinction, conservation focal points would not be placed on animals like elephants or tigers, as they generally are now, but on more core species like rats or fungus that are modernly abundant. For a mass extinction to be underway, mankind must have already passed the point of no return, which is a line that is perhaps unremarkable and difficult to pinpoint. As impending doom is still reversible when looking at the current status of global biodiversity, this alone would be the reasoning behind why a mass extinction is not yet in play. The negative consequences of human impact are hardly contested.
Strong concentrations of chemicals have been used for human use, crop aids like nitrogen have been harnessed and heavily synthesized, applied more as agricultural fertilizers than fixed naturally within all natural soils on Earth. The abundance of nitrogen in the environment, through application onto crops as well as concentrated in the manure of livestock, has led to the increase of eutrophication after it travels into the water system (PAUL C). The spike in fossil fuel emissions through activities like animal and crop agriculture and deforestation have led to the release of a number of greenhouse gases. They become substantially more and more concentrated in the atmosphere, particularly throughout the past two centuries. Carbon dioxide (CO2) levels have risen by more than 30% and methane (CH4) by more than 100%. The Intergovernmental Panel on Climate Change reported in 1995 that “The balance of evidence suggests a discernible human influence on global climate” and followed up in 2001 stating that “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities”.
All of these factors contribute to ecosystem alterations, and the quick changes that organisms must adapt to are coming in too rapidly for them to keep up. A study was conducted looking at and comparing a compilation of statistics regarding a range of contemporary conservation concerns between 1890 and 1990. The results of this study indicated that the world population has increased by a factor of four, urban population by 13, industrial outputs by 40, energy use by 16, CO2 emissions by 17. During this time, conservation efforts struggled. Blue whale populations decreased by 99.7% and forest area by 20%. The numbers regarding the increase of activities associated with human population growth directly correspond with the decrease of things like the biodiversity and old growth forested areas. The spike in human populations come hand in hand with a variety of environmental stressors, with a significant emphasis on biodiversity loss.