So what is the biosphere?
Put simply, it's the bit on the outside of the planet, where all living things are able to exist. It includes the deepest layers of soils and ocean trenches, upwards to the highest levels of the atmosphere in which any form of life (including dormant spores, bacteria or other cells) is present.
We humans are a product of the biosphere, just as apples, caterpillars and rocks are. We not only live in the biosphere but are absolutely dependent upon it for almost every aspect of our existence. We constitute an integral part of the biosphere, but we are so prominent and active that we are now changing it very considerably - and much too rapidly for our future safety and survival.
Read More: Threats to the Biosphere