Biosphere (National Geographic Society):
The biosphere is made up of the parts of Earth where life exists. The biosphere extends from the deepest root systems of trees, to the dark environment of ocean trenches, to lush rain forests and high mountaintops.
Scientists describe the Earth in terms of spheres. The solid surface layer of the Earth is the lithosphere. The atmosphere is the layer of air that stretches above the lithosphere. The Earth’s water—on the surface, in the ground, and in the air—makes up the hydrosphere.
Since life exists on the ground, in the air, and in the water, the biosphere overlaps all these spheres. Although the biosphere measures about 20 kilometers (12 miles) from top to bottom, almost all life exists between about 500 meters (1,640 feet) below the ocean’s surface to about 6 kilometers (3.75 miles) above sea level.
Origin of the Biosphere
The biosphere has existed for about 3.5 billion years. The biosphere’s earliest life-forms, called prokaryotes, survived without oxygen. Ancient prokaryotes included single-celled organisms such as bacteria and archaea.
Some prokaryotes developed a unique chemical process. They were able to use sunlight to make simple sugars and oxygen out of water and carbon dioxide, a process called photosynthesis. These photosynthetic organisms were so plentiful that they changed the biosphere. Over a long period of time, the atmosphere developed a mix of oxygen and other gases that could sustain new forms of life.
The addition of oxygen to the biosphere allowed more complex life-forms to evolve. Millions of different plants and other photosynthetic species developed. Animals, which consume plants (and other animals) evolved. Bacteria and other organisms evolved to decompose, or break down, dead animals and plants.
The biosphere benefits from this food web. The remains of dead plants and animals release nutrients into the soil and ocean. These nutrients are re-absorbed by growing plants. This exchange of food and energy makes the biosphere a self-supporting and self-regulating system.
The biosphere is sometimes thought of as one large ecosystem—a complex community of living and nonliving things functioning as a single unit. More often, however, the biosphere is described as having many ecosystems.
People play an important part in maintaining the flow of energy in the biosphere. Sometimes, however, people disrupt the flow. For example, in the atmosphere, oxygen levels decrease and carbon dioxide levels increase when people clear forests or burn fossil fuels such as coal and oil. Oil spills and industrial wastes threaten life in the hydrosphere. The future of the biosphere will depend on how people interact with other living things within the zone of life.
In the early 1970s, the United Nations established a project called Man and the Biosphere Programme (MAB), which promotes sustainable development. A network of biosphere reserves exists to establish a working, balanced relationship between people and the natural world.
Currently, there are 563 biosphere reserves all over the world. The first biosphere reserve was established in Yangambi, Democratic Republic of Congo. Yangambi, in the fertile Congo River Basin, has 32,000 species of trees and such endemic species as forest elephants and red river hogs. The biosphere reserve at Yangambi supports activities such as sustainable agriculture, hunting, and mining.
One of the newest biosphere reserves is in Yayu, Ethiopia. The area is developed for agriculture. Crops such as honey, timber, and fruit are regularly cultivated. However, Yayu’s most profitable and valuable resource is an indigenous species of plant, Coffea arabica. This shrub is the source of coffee. Yayu has the largest source of wild Coffea arabica in the world.
The biosphere is simply the home of all known life that has ever existed in the entire universe.
No Sun, No Life On Earth (BASF):
The sun is a huge nuclear reactor in the center of our solar system. Over a billion-years, hydrogen converted to helium at the core of the sun where the temperature is an unbelievable 15 million°C. A massive amount of energy is continuously released. It flows as radiation from the surface into space, warms our planet and sets in motion many chemical and physical processes.
Without sunlight, it would be bleak on earth. There wouldn’t be any plants, animals and people. There would be no other form of life. No fossil energy sources such as coal, oil and natural gas would be available to generate energy.
The sun keeps the engine running for the water cycle: evaporation → cloud formation → precipitation. And it shapes the weather on earth by heating the earth’s surface to varying degrees. Wind and hydropower plants? Solar power systems? Without sun, these wouldn’t work.
light: brighter than a million light bulbs
Warmth: not too much and not too little
The sun sustains all life on earth, it shines on us, warms the earth, the seas, the atmosphere, it influences the climate, it causes dry periods and ice ages, it causes wind, which blows over the earth and determines our weather. It’s storms disrupts radio communication, causes electrical discharges, and even tree rings are marked with radioactivity.
DIE SONNE, 1997
Rain: a never-ending cycle
It’s always raining somewhere in the world. By the way, the place with the highest rainfall in the world is in Hawaii: at Mount Wai’ale’ale on the island of Kauai, it rains an average of 335 days a year with 12,000 millimeters of raindrops per square meter!
Rivers are constantly carrying rain water back to the ocean. Why doesn’t the ocean sometimes overflow? You guessed it, the sun is responsible. All the earth’s water flows in a cycle. The warm rays of the sun evaporate the water from the earth’s surface, including the ocean’s water. That’s why the sea level stays the same all the time. The vapor rises until there is colder air. Then tiny droplets settle on dust particles and form clouds.
If the cloud becomes too heavy or hits a mountain, the water falls as rain on the ground. Seas, rivers and lakes are replenished. The water that falls to the ground seeps into the groundwater and then flows into the rivers — or evaporates from buildings, roads and all sealed surfaces becoming a part of the water cycle again.
Wind: air in motion
In fact, wind can only exist with the sun. The sun doesn’t heat the earth evenly. Some air in the atmosphere heats up faster than other depending on the latitude. Also, there are significant temperature differences between the different layers of air.
Warm air masses act like a magnet and attract cold air. The movement of air masses give rise to winds and depending on the strength, we experience a light breeze, high winds, or a dangerous storm. Over the ocean, winds constantly blow at varying strengths, sometimes lighter sometimes stronger. This is also caused by the sun. When the sun shines, the air heats up faster over land than over the ocean. The warmer air expands and rises. Cold air flows into the empty space that has been created at the surface. This movement of air mass is what we experience as wind.
On a side note: At night, it cools down faster on land compared to the ocean. That’s why the wind direction turns at night and blows towards the ocean.