Introduction
Because of forces that are beyond human control, the earth’s atmosphere has been undergoing gradual changes, a process called evolution. It is evident based on historical facts as laid by archeologists and geologists that all the constituents of the earth have changed with time. This change can be realised upon considering the various geological ages that include the Cenozoic period, the Mesozoic period, the Paleozoic period, and the Precambrian period (Gradstein, Ogg & Smith 2004, p. 589), which are addressed later in the paper.
A primitive person would wonder how the change is possible until an expert presents a detailed analysis of the situation of the earth’s atmosphere as recorded within a span of 2 million years, for instance. Since this is a mystery for many, the paper presents this analysis by giving a clear picture of how the earth’s atmosphere has evolved over time besides showing how the atmosphere has led to the origin, development, and survival of different living things.
How the earth’s atmosphere has evolved over time
The earth’s atmosphere has evolved over a long period. This evolution has brought about many changes in the shape and composition of the earth in terms of both living and non-living matter. It is believed that the different geological evolutions of the earth and the atmosphere have come up with very new species of animals following a transformation of the then existing animals, as well as extinction of some species of the living and non-living organisms.
This is all attributed to the changes in the habitation that the organisms had been adapted to by making the habitation friendly or making it harsh for the survival of the different species. At the same time, it is also believed to have forced some species to change some of their physiological features for better survival (Grotzinger, Bowing, Saylor & Kaufman 1995, p. 599). Scientists believe that the earth came into existence some 4.5 billion years ago.
Then, it was formed from gases emanating from volcanic emissions, which were the dominant activities then. It is believed that the atmosphere then was mostly made up of carbon dioxide gas with little or no oxygen at all. With time, the earth cooled down due to the subsiding of volcanic activities. The vapour that had so much filled the air also cooled down and condensed to form water, which collected itself to form the different water bodies that exist up to date.
It is believed that the carbon dioxide gas that filled the air for a long time was then trapped in sedimentary rocks, absorbed by vegetation, as well as the large water bodies that came into existence after wards. Photosynthetic organisms arose naturally leading to so much reduction in the carbon dioxide in the atmosphere, as organisms such as the blue-green algae fed off the carbon dioxide in exchange of oxygen (Cesar 2009, p.16).
All these processes happened over a long period in periods of several hundreds of millions years. Scientifically, the atmosphere is divided into four stages of evolution namely the origin, the chemical or pre-biological era, the microbial era, and the biological era. Each era is characterised by a major activity that happened during that time to define it. The reduction in carbon dioxide and the increase in nitrogen and oxygen in the atmosphere define the origin era.
This led to the creation of the ozone, which encouraged the development of other living organisms. The ozone came about when sunrays in the stratosphere acted upon oxygen to form a buffer-like layer in the atmosphere that is thought to protect the earth from the damaging sunrays. This is said to have happened over two billion years ago. There are four main eras of the present-day atmosphere evolution: the origin, the chemical or pre-biological era, the microbial era and the biological era.
A major activity that was dominant among other activities then defines each of these eras. The origin, which people believe to have occurred over two billion years ago, is majorly marked by the reduction in the amount of carbon dioxide and the increase of oxygen and nitrogen in the atmosphere. It stands out as the precursor to life: the stage that prepared the earth for habitation by living organisms.
Today, the earth is in an era defined as the Cambrian where living things dominate the earth surface more than before. The amount of oxygen is now at around 20% of the atmosphere. This is just enough to create a sustainable balance between all living things and other reactions. Scientists believe that, in case of an increase in the amount of oxygen in the atmosphere, almost everything will become combustible.
A lower level of the same, on the other hand, will drastically affect combustion abilities of the normally combustible elements. The present day atmosphere has evolved to the extent that, once more, there is a high level of carbon dioxide being emitted into the atmosphere. It is now becoming a threat to the survival of all the living things that have so far survived the different ages of atmospheric revolution.
Presently, there is a threat to the ozone layer with the belief that it is wearing off due to the alarming increase in carbon dioxide in the atmosphere besides a corresponding increase of other gases that are supposed to be in minute proportions. Consequently, this is a big danger to the existence and perfect functioning of the ozone layer.
How the atmosphere has helped life originate, survive, and develop?
The atmosphere has helped life to originate, survive, and develop in many different ways. When the earth came into formation several billion years ago, there were no living organisms of any kind. This was due to the high temperatures that were always at play then. As explained above, the reduction of carbon dioxide from the atmosphere followed by a corresponding increase of oxygen into the atmosphere enabled living things to develop from minute primitive organisms to fully-fledged mammoth creatures.
The oxygen in the air is the most important element for the survival of any living thing because living organisms use oxygen, as air, for the purpose of metabolism, which leads to cell division. The atmosphere also provides atmospheric pressure, which balances everything on the earth surface by putting them into place. The atmospheric pressure is the pressure of the air exerted on the surface of the earth. It helps, for example, the human body to balance the pressure produced by the body.
Without the atmospheric pressure, most living things would burst from their own internal pressure like blood pressure in human beings. The atmosphere balances the amounts of different types of air found on the earth surface. As Furin states, “more than the required amount of any gas might be detrimental to the survival of any living organisms” (2006, p.1110). Therefore, the atmosphere distributes these gases according to the natural needs of each organism.
The ozone layer acts as a protective blanket against the sun’s ultraviolet rays towards the living organisms found on the earth’s surface, which can easily be exterminated when exposed to these rays (Kent & Olsen 2008, p. 69). Therefore, in this way, the atmosphere has provided a safe haven for living things to live and develop according to their adaptative needs. Life, on the other hand, has changed the atmosphere in so many ways.
Plants, on one hand, have shaped the structure of the atmosphere for a long time by pumping the much-needed oxygen into the atmosphere. Through photosynthesis, which is a process the plants use to make their own food, plants take in carbon dioxide mostly through their leaves and mix it with chlorophyll, which is the green matter found in the leaves, to produce oxygen as a by-product (Giordano & Beardall 2009, p. 78).
Through this process, the atmosphere is ridden off carbon dioxide and is replenished with oxygen. This control of carbon dioxide protects the ozone layer from damage through carbon dioxide emissions (Byatt 2004, p. 19). Living things have become the biggest producers of carbon dioxide. With the availability of a good environment to reproduce, living things have reproduced massively in that, when they die, they decay with part of that decay process producing lots of carbon into the atmosphere.
Human beings have also contributed to the destruction of the atmosphere, as well as its protection in almost equal measures. Due to the development of the human society, the need to produce enough food and other items for human beings convenience has increased. Man uses fertilisers to boost soil fertility to achieve high crop yields.
This leads to pollution of the atmosphere because the chemical fertilisers react with the soil and plants later escaping in gaseous forms that end up into the atmosphere (Darko & Isakov 2000, p. 91). Human beings have also come up with industries that emit carbon emissions in large quantities thus leading to a very fast degradation of not just the ozone layer, but also general pollution of the atmosphere (Donald & Kenneth 2000, p. 17).
Humans have also been at the forefront in protecting the atmosphere through legislation of pollution policies, as well as coming up with technology that will protect the environment. In most countries, legislation has been passed to control the acceptable amount of carbon emissions that any given industry can be allowed to release into the atmosphere. These measures have been put in place to protect the fragile ecosystem that is so dependent on the atmosphere (Shafiqur & Luai 2012, p.19).
Some companies have also come up with the carbon credit scheme as a way to compensate on pollution. In this scheme, individuals are paid for their efforts to reduce carbon dioxide from the atmosphere. Most industries are now encouraged to pursue the use of green energy or renewable energy as a departure from fossil energy.
Conclusion
In conclusion, the earth’s atmosphere is a very important integral part of the earth and all the living and non-living things. Although the evolution of the atmosphere and the earth is a matter of debate, it is undisputed that the atmosphere holds the key to life on this planet earth.
Matters to do with the existence of the ozone are still debatable because, so far, the ozone issue remains hypothetical and only understandable by scientists in that field. Though the existence of the atmosphere is true, its origin remains a big point for debate depending on what side of the divide between religion and science one stands on.
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