About a fortnight ago, a group of geoscientists gathered at Cape Town, South Africa, and have recommended that mankind’s impact on Mother Earth has been so profound in recent years, that it is time to describe a new geological epoch in the history of earth, calling it Anthropocene ( Anthropo, from the Greek for humankind, and cene from the Greek kainos, Latinised as caenus or cene, meaning new). They suggested that the present epoch, described so far as the Holocene ( Holo, from the Greek for whole/entire), has given rise to the Anthropocene. It is suggested to start from 66 years ago (1950), thus halting Holocene, an epoch that started about 11,700 years ago, when the last Ice Age occurred. At that time, most of the Ice Age animals - the woolly mammoths, sabre-toothed tigers and giant bears - had died out, and by 11,000 years ago, humans had occupied a significant part of the earth as hunter gatherers as well as settled communities, inventing farming and agriculture.
What hath man wrought! What has led us to redefine our epoch, from a natural one into a man-induced one? Back 11,000 years ago, the carbon dioxide (or CO2) level in the atmosphere surrounding the globe was about 220 parts per million (ppm); even 8,000 years ago, it was about 260 ppm. But starting the nineteenth century, when the industrial revolution started in the West, coal from the earth and beneath it was used extensively as the fuel for transport and industry. The other major fossil fuels, oil (petroleum) and natural gas were discovered and put to use on a large scale. Burning carbon-rich fossil fuel liberates CO2. And CO2 is an example of what is referred to as a Greenhouse gas, which lets sunlight in, but traps the heat radiation that the earth and its oceans emit in return. (An easy example is when a car is parked in the sun, with its glass windows shut, sunlight enters the inside of the car, warming it, but the outgoing heat is trapped by the closed windows; the same effect is utilised in greenhouses, where plants and vegetables are grown in cold climate; hence the name greenhouse effect).
Non-stop burning of fossil fuels for industry, transport and other uses over these years has accumulated a large amount of CO2, which does not escape the earth (thanks to the gravitational pull of the earth; lighter gases such as hydrogen or helium gases escape, which is why they are not earthbound). Thus, over time, the level of CO2 in the atmosphere has shot up from 280 ppm at the start of the Industrial Revolution to 413 ppm today. As a result, the average surface temperature over these two centuries has gone up by 1.5 degrees Centigrade. This has also started melting glaciers and raised the sea level by 3.2 mm every year. (Indeed, the island nation, Maldives, is worried that at this rate, some of its islands may be submerged in the near future, and had actually asked Australia whether they could buy land and move there!).
Added to the warming of the oceans and landmass caused by the Greenhouse gases (CO2, NO, Ozone, methane…), are the plastics and their debris, strewn all across the world and its oceans. Plastic pollution is an even more recent phenomenon . In addition, increase in human population from 1.2 billion in 1850 to the current 7 billion, has led to massive destruction of forests and animals therein has led to a crowding problem, and its associated effects.
Is this the first such massive upheaval of the earth’s atmosphere through a gas? Well, such a thing happened long long ago, during what is called the “Oxygen Catastrophe” (or more politely as the Great Oxygenation Event) which occurred about 2.4 billion years ago. Those days, the earth was rich in a set of microbes called cyanobacteria, which started the early events of photosynthesis, wherein the microbe used CO2 for energy production and emitted oxygen gas (O2) as the waste material. Cyanobacteria reproduce very fast (doubling every 30 minutes), thus leading to vast amounts of oxygen in the atmosphere. Some of this was ‘fixed’ by iron and organic matter of earth, but the rest soon led the ‘poisonous’ gas, oxygen, attain levels of about 20 per cent in the air. This burnt off many living forms and it took a long time before oxygen- using life forms (aerobics) started flourishing about 500 million years later.
Well, we do not have the luxury of time, and need to drastically cut down our use of fossil fuels, plastics and all other material that have led to this unfortunate climate change. As usual, vested interests still refuse to believe that climate change has occurred, and that the use of fossil fuels is not responsible for this dangerous ‘greenhouse gas catastrophe’. We need to be at least wise now and try hard to stop further damage to Mother Earth. Every little bit helps; little drops of water make the mighty ocean.
D. Balasubramanian
dbala@lvpei.org
