04 0.3 The four spheres of the natural environment
The natural environment consists of four interconnected spheres:
1Hydrosphere
Meaning
- all the water on, under and above Earth's surface
Examples
- oceans, rivers, glaciers, groundwater, water vapour
2Atmosphere
Meaning
- the envelope of gases surrounding Earth
Examples
- air, clouds, ozone layer
3Lithosphere
Meaning
- the solid rocky crust and upper mantle, including soil
Examples
- rocks, minerals, mountains, soil
4Biosphere
Meaning
- the zone where life exists; it overlaps the other three
Examples
- plants, animals, microbes, humans
- These four spheres are in continuous change, they affect one another, and they are affected by human activities.
- For example, burning fuel (human activity) adds carbon dioxide to the atmosphere; some of it dissolves in the ocean (hydrosphere), changes its acidity, and harms shell-forming animals (biosphere) that build their shells from calcium carbonate taken from the water (a lithosphere-type material).
- One event, four spheres.
- Keep this picture in mind: almost every question in this book can be answered by following matter and energy from one sphere to another.