Early earth atmosphere
Oxygen was nearly absent in the atmosphere of early Earth, its atmosphere was mainly dominated by carbon dioxide CO2 and water H2O. It was similar to the atmosphere of Venus today. H2O and CO2 are efficient greenhouse gases, so the earth was also very hot back then.
SO HOW DID ALL THIS CHANGE?
Well as the earth got older this all changed due to various reasons:
Water vapour was removed from the atmosphere by precipitation, ending up in oceans, lakes, etc.
CO2 removed by dissolving into rain which reacted to form carbon compounds in rocks. CO2 was also removed by dissolving into the oceans.
Later groups of one-celled organisms started to grow. They were the bacteria or prokaryotes. These creatures were the earliest evidence of life on earth and they were also the first organisms to develop photosynthesis. Thus from this photosynthesis a lot of the CO2 was removed and oxygen was added.
Thus the:
- Atmosphere became MUCH less dense, as H2O and CO2 were removed.
- Oxygen became a major constituent due to the photosynthesis
PRESENT EARTH'S ATMOSPHERE:
Nitrogen -77%
Oxygen -21%
Argon -0.9%
Other -1.1%
How deforestation increases the CO2 levels and the Green house effects:
Most modern countries in the world pretty well have already deforested their country. Now many under developed (LEDCS) are also doing the same for the economy of their county and to provide land for agriculture. This not only knows kills of millions of species and their habitats but also causes a major increase in the green house gas, carbon dioxide (CO2).
This deforestation increases the CO2 in atmosphere in several ways:
- About half of the trees cut are used for burning which releases CO2 directly. The remaining of the fallen trees also releases CO2 when they are decayed.
- Trees take CO2 for photosynthesis and releases oxygen, thus removing these trees means lesser CO2 is removed from the atmosphere
Negative effect on co2 level through burning of forests
Beginning in 1700, the Industrial Revolution increased the amount of carbon dioxide entering the atmosphere. The pollution from fossil fuel combustion and the deforestation of woodland, and forests has changed the atmosphere of our earth.
The amount of heat energy added to the atmosphere by the greenhouse effect is controlled by the concentration of greenhouse gases in the Earth's atmosphere. All of the major greenhouse gases have increased in concentration since the beginning of the Industrial Revolution (about 1700 AD). As a result of these higher concentrations, scientists predict that the greenhouse effect will change the Earth's climate. Predicting that the doubling of the concentration of the main greenhouse gas, carbon dioxide may raise the average global temperature between 1 and 3° Celsius. The negative effects that are predicted are increased cloud cover which would make the Earth warmer. Increasing the Earth's temperature would cause the oceans to evaporate greater amounts of water, causing the atmosphere to become cloudier and denser.
Photosynthesis it’s part in maintaining the greenhouse effect
Photosynthesis converts carbon dioxide from the air to carbohydrates and other kinds of "fixed" carbon and releases oxygen to the atmosphere. When we burn firewood, ethanol, or coal, oil and other fossil fuels, carbon dioxide is released back to the atmosphere. Thus, carbon dioxide which was removed from the atmosphere over millions of years is being replaced very quickly through our consumption of these fuels. The increase in carbon dioxide and related gases is bound to affect our atmosphere. As photosynthesis consumes carbon dioxide and releases oxygen, it helps to balance the effect of combustion of fossil fuels.
Strategies for reducing CO2 level
They are many ways in which you can reduce the CO2 level but they are expensive. If every one agreed to do it all you had to do was grow more trees. But it’s not as easy as I think the only way to manage this problem is to put iron in the sea which would increase the number of the prokaryote found in the ocean thus your photosynthesis would increase and more carbon dioxide would be absorbed in the ocean.
