The biosphere is the sum of all regions on the Earth that support life. The biosphere is subdivided into five subcategories known as biomes which include forests, aquatic zones, deserts, tundras, and grasslands.
Essentially anywhere that life exists on Earth is a part of the biosphere. Although the biosphere encompasses a region of 20 kilometers from top to bottom, the vast majority of life can be found within 500 meters below sea level to 6 kilometers above it.
The Earth's biosphere has been around for about 3.5 billion years. Early life forms existed without without the free oxygen that life relies on today, and developed the incredible process of photosynthesis. These life forms created most of the plentiful atmospheric oxygen that is seen today through this process, which allows for more complex forms of life to thrive. Today there is a tremendous amount of biodiversity within the world's ecosystems, and the biosphere as whole can be thought of as one large ecosystem. To learn more about the history of atmospheric oxygen please see here.
The biosphere and its components have been relatively stable for thousands of years, however humans have recently affected its flows. Acts like deforestation and burning of fossil fuels have negative environmental impacts which directly affect the biosphere. Carbon dioxide and emissions of various pollutants adversely effect all kinds of life forms.
One specific concern is the greenhouse gas emissions that are attributed to global warming. The change this has on the global climate is of direct concern to the biosphere. Floods and droughts are expected to intensify, which can lead to many other consequences such as famine. Melting of polar ice is another result of warming, which could displace many forms of life, as well as cause extreme events all around the globe.
Many groups are putting in efforts to lessen the strain that humans put on the biosphere. There are 563 biosphere reserves worldwide which exist to establish a working, balanced relationship between people and the natural world.
Click here for an interactive map of all biosphere reserves around the globe.