Want to stay on top of all the space news? Follow @universetoday on TwitterThe biosphere is the net sum of all of the ecosystems on Earth. It is often referred to as the Earth’s life zone. In the most broad sense of the word, in biophysiology, biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, hydrosphere, and the atmosphere. It is thought that the biosphere has evolved through a process known as biogenesis, which began more than 3.5 billion years ago. The term was coined in 1875 by Eduard Suess. He defined it as the place on Earth where life dwells.
There is a theory that the biosphere itself is a living organism. This is called the Gaia hypothesis. An atmospheric scientist from the United Kingdom, James Lovelock, proposed the Gaia hypothesis to explain how biotic and abiotic factors interact in the biosphere. The theory postulates that the atmosphere, geosphere, and hydrosphere are cooperating systems that yield a biosphere full of life. Later, the theory was added to, specifically noting the ties between the biosphere and other Earth systems. For example, when carbon dioxide levels increase in the atmosphere, plants grow more quickly. As their growth continues, they remove more and more carbon dioxide from the atmosphere.
It is hard to accurately measure the biosphere because nearly every part of the planet supports life of some kind. Recent advances in microbiology have demonstrated that microbes live deep beneath the Earth’s terrestrial surface, and that the total mass of microbial life in “uninhabitable zones” may exceed all animal and plant life on the surface. You have to take into account that birds typically fly at altitudes of 650 to 1800 meters, and fish can be found down to 8,372 meters below the surface. There are even more extreme heights and depths where life has been found on our planet. The versatility of life on Earth is the very reason that it is hard to measure where life begins and ends in the biosphere.
To make things even more interesting, our biosphere is divided into a number of biomes, inhabited by broadly similar flora and fauna. On land, biomes are separated primarily by latitude. Terrestrial biomes lying within the Arctic and Antarctic Circle are relatively barren of plant and animal life, while most of the more populous biomes lie near the equator. Terrestrial organisms in temperate and Arctic biomes have relatively small amounts of total biomass, smaller energy budgets, and display prominent adaptations to cold, including world-spanning migrations, social adaptations, homeothermy, estivation and multiple layers of insulation.
There is a good article about the biosphere here. We offer a great article here on Universe Today about how long life could continue on this planet. Astronomy Cast offers a good episode about the study of life in the universe, called astrobiology.