What won't we be able to do if we don't the earth

You won't be able to breathe if you don't take care of trees for example

If we don't save the river, we won't drink water. Without water, the trees won't produce oxygen. Without oxygen, we won't breath, we won't eat vegetables. Animals won't eat plants, too. Animals will die.
The Earth will die.

Sorry for my bad English, I'm Brazilian =)

C.about 10% i think

The answer is the magnetosphere.