A new geological epoch and the sixth mass extinction
By Afroz Ahmad Shah
The geological records tell us that Earth is about 4.5 to 4.6 billion years old. This number is calculated by various vigorous scientific investigations, which deal with the dating of minerals and other records preserved within rocks. Accordingly, Earth has been divided into several geological time periods. Throughout its past, it has witnessed a number of changes, both minor and major, which are present within the rock strata. Geologists have studied these strata over decades and decoded the conditions of their formation and deposition. These strata also preserve evidences of faunal and floral changes.
It has been reported that earth has witnessed five major mass extinctions. The fossil records tell us that the first one occurred about 434 million years ago, in which 60% of all genera, of both terrestrial and marine life worldwide were eliminated. The second one occurred about 360 million years ago and eliminated a major portion marine life in which coral reefs were the worst affected species. This had little impact on terrestrial fauna. The third major extinction occurred about 251 million years ago, when perhaps 80 to 95% of all marine species went extinct. The fourth extinction occurred around 205 million years ago, in which about half of all marine invertebrates and about 80% of land quadrupeds (animals having four feet) went extinct. The fifth extinction might have occurred around 65 million years ago when dinosaurs went extinct and about 60% of marine life was wiped out. The sixth mass extinction, which is an ongoing process, is quite evident by the extinction of various species at an alarming rate. It is predicted by the geologists that this extinction may be much worst than all the previous ones. It is driven primarily by the overexploitation of both space and resources by the humans.
There are a growing, yet significant number of evidences to advocate for a separate geological epoch in the time during which momentous changes occurred on this planet. Consequently, a separate epoch for human induced changes on planet Earth was coined by Prof. Paul J. Crutzen, in 2002, he named it Anthropocene (the term has Greek roots: anthropo- meaning “human” and -cene meaning “new”). Though, it is not formally accepted by the top geological bodies, responsible for the nomenclature, but, the evidences are striking. This was advocated by a growing number of inflectional geologists, biologists and ecologists, who argue in favour of Anthropocene.
“There is growing, yet, significant number of evidences to advocate for a separate geological epoch in the time during which momentous changes have occurred on the planet earth”.
Human induced changes may have started in the latter part of the eighteenth century. It was at this time when signs of growing global concentrations of carbon dioxide and methane were identified in the air trapped within the polar ice core samples. It was followed by a global consciousness of the role played by humans in modifying the environment.
The exponential rise in the human population, which according to the latest statistics may touch more than 10 billion in this century, will put a lot of pressure and constrains on the Earth’s environment and resources. More land space will be required to accommodate the growing numbers, which will ultimately put pressure to remove forests. In a study conducted in 2002, about 30-50% of the planet’s space has been exploited by us. It means within this century the percentage will increase, which will significantly affect the environment. In the last century human energy consumption has grown 16-fold, which resulted in a total of about 160 million tonnes of sulphur dioxide emission per year. This is about twice the natural emission. To meet the demand of energy supply in the last century, a substantial quantity of fossil-fuels were burned and more nitrogen fertilisers were used, which caused a considerable damage to the environment. It is estimated that carbon dioxide concentration has risen to about 30% and methane by more than 100%, which is the highest level recorded over the past 400 millennia. This will increase the threat to the Earth’s environment.
Therefore, the earth scientists and other researchers must largely engage in public activities and propagate the message to masses about the significance of the Earth system processes. How the Earth interacts with its outer environment and what is the role of man in modifying its delicate environment is practically important to understand. This would make people realise how their actions can modify and change its behaviour. The various forced anthropogenic alterations on the Earth’s surface will ultimately affect the existence of life. Hence such consciousness must develop at an early stage, so that precautionary measures can be taken and possible dangers mitigated. This requires us to have a well informed society, conscious of its complex relationship with the planet.
Afroz Ahmad Shah is a research fellow at Earth Observatory of Singapore, Nanyang Technological University, Singapore.