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Evolution of the Atmosphere!
The earth used to be molten for millions of years; it was so hot, that any
atmosphere would just boil away! Eventually a thin crust formed on the
earth. The volcanoes gave out lots of different gases, including Carbon
dioxide and small amounts of water vapour; we think this is how the
oceans formed. So according to this theory, the earth used to be nearly
ALL carbon dioxide, and practically no oxygen (similar to mars and Venus
today). The oceans formed when the water vapour in the air condensed.
A lot of the carbon dioxide dissolved into the oceans. Marine organisms
developed, which took in carbon dioxide. When they died they were
buried under layers of sediment and the carbon dioxide got locked up
into carbonate rocks.
The build up of oxygen in the atmosphere killed off some early organisms
that couldn't tolerate it, but allowed more complex organisms to
develop and evolve. The oxygen also created the ozone layer, which
blocked harmful sun rays from the sun and enabled even more complex
organisms to evolve- us! There is not much carbon dioxide left now.
Human activity affects the atmosphere!
1. Burning fossil fuels releases carbon dioxide and sulphur into the
atmosphere, these are green house gases; they increase the
temperature of the earth.
2. Deforestation causes increase in levels of carbon dioxide, tree's
take in carbon dioxide when they photosynthesise and release
oxygen, so if there is less trees then there is less oxygen being
taken out of the atmosphere.
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Livestock farming releases Methane into the atmosphere, animals
produce it when they pass wind- LOL .
Volcanic activity is changing the atmosphere
Sulfur dioxide can be thrown up into the air when volcanoes erupt,
this can cause acid rain. Carbon dioxide is also released.…read more