Biosphere

The biosphere is that part of Earth that contains life. This worldwide ecosystem ( a area in which living things interact with each other and the environment) is made up of the land, water, and atmosphere that support life, and includes every part of Earth where life exists. Its many parts are linked together by nutrient cycles.

The biosphere can be described as all of the world's ecosystems, or the worldwide ecosystem. As such, it consists of Earth's lithosphere, atmosphere, and hydrosphere. The lithosphere includes all of Earth's surface layers of solid substances like soil and rocks. The atmosphere is the envelope of gases or air that completely surround the planet. The hydrosphere includes all of the lakes, rivers, and oceans on its surface. All of the elements and forces in these three spheres are constantly part of the many chemical, biological, and physical processes that make the entire "bio-sphere" or "life-sphere" what it is. To date, no other planet besides Earth has been discovered that contains a biosphere or living world.

EDUARD SUESS COINS THE TERM BIOSPHERE

The term biosphere was first used by the Austrian geologist Eduard Suess (1831–1914) in 1875 to describe that part of the Earth that contains life. This concept had little impact on the scientific community until it was discussed by the Russian mineralogist, Vladimir I. Vernadsky (1863–1945) in his 1926 book. Vernadsky argued that in order to study the biosphere, scientists from many fields like geology, chemistry, and biology had to work together.

Earth's biosphere can be considered to be thousands of feet thick—from the bottom of the oceans to about 30,000 feet (9.144 kilometers) above sea level. However, given the size of the entire Earth, this is a fairly thin layer. In fact, most of the life that does exist within the biosphere can be found in the narrow band just below sea level to about 20,000 feet (6.096 kilometers) up. That height is about the limit for animals and most plants to live. Scientists consider Earth's biosphere a closed system in which the only thing ever added is sunlight. Living things in the biosphere need energy and nutrients and an appropriate environment in order to live and reproduce. The Sun is the ultimate energy source for the biosphere, and its light energy is captured by green plants that use the process of photosynthesis to change light energy into chemical energy. This energy then passes through the biosphere from plants to other organisms and then to others again. It is eventually either lost in the form of heat to the environment or stored for a long time in organic molecules, such as carbon atoms are locked in coal underground. The biosphere can, therefore, be seen as a group of tightly interconnected recycling systems and subsystems that affect and influence each other.

THE BIOSPHERE CONSIDERED AS A GLOBAL CONCEPT

The global concept of the biosphere has become increasingly useful and important as technology allows the world to be considered in a truly global way. Spacecraft can not only provide images of the entire globe, but also can monitor the many systems that make up Earth's total environment. Today, therefore, the term biosphere is used most often when discussing the health of Earth. Current research focuses on the effects that human activities have on the health of the global environment (the biosphere). The pressures and demands of increasing populations have resulted in two major threats to the biosphere's well-being: the loss of natural resources and the effects of pollution. As more and more of the natural environment is destroyed, such as the continuing destruction of tropical rain forests, many scientists fear that the balance of nature may be so upset that it may permanently harm or change the biosphere. Many also fear that the pollution by-products of everyday modern life could become too great for the biosphere to bear and may permanently damage its systems. Activities such as fuel consumption (burning coal, oil, and gas) and the use of fertilizers could increase the levels of carbon dioxide, nitrogen, and phosphorous in the atmosphere and seriously alter the natural balance of the life-sustaining biosphere.

The concept of the biosphere is also at the center of a scientific debate as to whether Earth and its biosphere should be considered a living organism with self-regulating mechanisms. Called the "Gaia hypothesis," this idea was first put forth in the late 1970s by the British scientist, James Lovelock (1919– ), who argued that the biosphere is able to create and maintain the environment that most favors its own stability—as long as it is left alone. Lovelock argued that by tampering with and sometimes altering Earth's environmental balancing systems, humans are placing themselves and their planet at risk. He and his followers argue that such phenomena as global warming, or the greenhouse effect (caused by too much carbon dioxide in the atmosphere), and ozone depletion from pollution (the resulting decrease in protection from harmful ultraviolet radiation from the Sun, are evidence of a growing risk. Whether the Gaia hypothesis is right or wrong, it has been very useful in generating concern and research about people's influence on the worldwide ecosystem known as the biosphere.

[See alsoPhotosynthesis; Respiration ]