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| | Earth System Science II |
 | | The relative abundance of the elements composing the Earth is largely similar to that of the Sun and the Solar Nebula, and the Earth's `major elements' are therefore in order of decreasing valence or ionic charge (with the exception of phosphorus, sulphur, and carbon (P, S, C)): |
 | | For example, if global CO2 levels should rise, the Earth's atmosphere would warm, which would in turn increase precipitation and the rate of weathering, and also increase the amount of continental crust exposed to weathering as a result of the melting of the polar ice-caps. |
 | | Interestingly, if all the continents were to move to polar locations and be covered with ice, the average temperature of the Earth would increase because weathering as a control on CO2 levels would be insignificant. |
| instruct.uwo.ca /earth-sci/300b-001/erthsys2.htm (4021 words) |
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