Our learners at Bushwise are exposed on a daily basis to all kinds of wildlife and we constantly discuss the conservation of our natural world. They are also trained to educate their guests to be more conscious about their roles in conservation. Our learners often forget that our natural world is under global catastrophic risks and that the earth has seen five mass extinctions over the past 455 million years. These events are also known as the “Big Five” within geological circles.

What is a mass extinction? As per the definition in the dictionary – ‘The extinction of a large number of species within a relatively short period of geological time, thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt. At least five mass extinctions have been identified in the fossil record, coming at or toward the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods. The Permian extinction, which took place 245 million years ago, is the largest known mass extinction in the Earth’s history, resulting in the extinction of an estimated 90% of marine species. In the Cretaceous extinction, 65 million years ago, an estimated 75% of species, including the dinosaurs, became extinct, possibly as the result of an asteroid colliding with the earth.

This extinction is argued to be due to factors such as a catastrophic global event, widespread, or sudden environmental change that does not allow for most species to adapt.

The first mass extinction happened during the Ordovician period, 455 million years ago. This resulted in a death rate of 85% of species. It is believed that it was caused by non-anthropogenic events like rapid global cooling and falling sea levels. The second was during the Devonian period, some 340 MYA. With a 70% death rate, it is believed that it was also caused by non-anthropogenic events like asteroid impacts and rapid global cooling. The third was around 250MYA. During the Permian epoch. This eradicated 95% of species. The causes are also said to have been non-anthropogenic events like volcanic activity, global warming, and high CO2 and methane levels. The fourth was caused by Rapid global warming and increases in CO2 and methane levels about 200 MYA. This was the Triassic epoch and resulted in a 76% death rate. The last Mass extinction was the more familiar one that wiped out the dinosaurs 65 MYA. During the Cretaceous–Tertiary or K-T period. The overall death rate was 80% and it was probably caused by an asteroid impact, volcanic activity and falling sea levels. 

It is generally stated that the next mass extinction is not a matter of if but rather of when? But what will cause it? Well, that is what the whole debate is about. What are the global catastrophic risks that earth is possibly facing? It is basically anybody’s guess but I will just mention a few that are often debated by some of our Bushwise learners. Many are saying that the sixth mass extinction will be during the current epoch referred to as the Anthropocene, the age of humans. Modern human beings have existed for around 200,000 years and although this only represents 0,004% of the earth’s age, our impact on the planet is mammoth. 

It is often argued that species are becoming extinct 100 times faster than what they would without the impact of humans on the planet. Wildlife populations have more than halved since 1970, but in contrast to that is the fact that the human population has doubled in the same period. Just two hundred years ago, there were less than a billion people on earth. Today, there are around 7.6 billion and it’s still growing. According to the United Nations, unless we take action, there is likely to be 30% more humans by 2050, and 11 billion people by 2100. Only five times before in our planet’s history have so many species and so much biodiversity been lost so rapidly and extensively. The last time was when the dinosaurs were wiped out. Many scientists and conservationists describe the current loss of biodiversity as a biological annihilation and refer to it as the sixth mass extinction. If all critically endangered, endangered, or vulnerable species go extinct in the next 100 years or so, and if that rate of extinction continues without slowing down, we could approach the level of mass extinction as soon as 240 to 540 years from now. 

Just think of a few major current issues that are being caused by humans. Greenhouse effect, climate change, eutrophication of surface water bodies and many more. These all could very easily reach levels where it would be out of our control. One can’t help but wonder what will happen to the earth if all humans are eradicated from the globe. 

Here are some suggestions that could possibly cause or lead to a global catastrophic event that could possibly threaten the existence of mankind. A Rouge viral or bacterial pandemic.

According to Dr. Peter Daszak, a disease ecologist, there are currently around 1500 unknown viruses on the planet and there are five new emerging diseases per year. Any one of these can very easily become a global pandemic. Zoonotic viruses that spread from animals to humans are well known to cause serious global health risks. The ancient variola or smallpox virus, that is extremely contagious, is one of the most devastating diseases known to mankind. Humans have battled the virus for many years. In the 20th century alone, smallpox killed 300 million people worldwide. More recent examples are the Zoonotic SARS virus, H1N1 virus, and Ebola virus. 

There are currently a lot of advance research being carried out to find solutions for many human-related problems. Many people are aware of current nanotechnology, genetic engineering and stem cell research, with contradicting reports and statements with regard to the risks involved. For example, during genetic engineering, genes for antibiotic resistance are often used as “selectable markers.” Early in the engineering process, these markers help identify cells that have taken up foreign genes. Although these markers have no further use, the genes continue to be expressed in plant tissues. 

Many genetically engineered plant foods carry fully functioning antibiotic-resistance genes. When these antibiotic-resistance genes end up in our foods that contain vegetable matter, it could have lethal effects. For example, by eating these foods it could reduce the effectiveness of medical antibiotics used to combat diseases. More so, the resistance genes could be transferred to human or animal pathogens, making them impervious to antibiotics. If the transfer were to occur, it could aggravate the already serious health problem of antibiotic-resistant disease organisms. This could very well result in a global medical catastrophe of astronomical proportions.

Other suggestions of events that may cause the next mass extinction: 

Impacts by asteroids, meteorites. flood basalt events, volcanic eruptions, ocean level falls, clathrate gun hypothesis – This refers to a proposed explanation for the periods of rapid warming during the current age. Anoxic events – This is when oceans become completely depleted of oxygen. Hydrogen sulphide emissions from the seas. Oceanic overturn.

A nearby nova, supernova or gamma-ray bursts. Geomagnetic reversal. Nuclear or biological warfare. 

In Conclusion:

Homo sapiens is the only extant human species. The name is Latin for “wise man” and was introduced in 1758 by Carl Linnaeus. Our activity is causing environmental degradation, which is the deterioration of the environment through depletion of resources such as air, water and soil. The destruction of ecosystems, habitat destruction, the extinction of wildlife, and pollution. Let us hope that we are truly wise enough to manage our negative impact and prevent our species, homo sapiens, to be the cause of the sixth mass extinction.

As you probably know, many people are debating whether we really are in the throes of a sixth mass extinction. What is your opinion?

Blow written by Gerhard van Niekerk


















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