The two changes in the use of the earth’s resources that had the greatest effect on the world population were the Neolithic and the industrial revolutions.
The Neolithic revolution (a.k.a. agricultural revolution) was a change in the way of life of our ancestors. It took place about 8000 years ago among various tribes in Asia and the Middle East. It included a transition from foraging and hunting to the domestication of animals (most probably starting with the dog) and to farming. Tribes settled in fertile areas and formed agricultural communities many of which grew into villages and cities. This relatively stable way of life and the more reliable food supply (and surplus) led to the development of new professions, to labor specialization and ultimately to the stratification of these societies.
Improved conditions of life led to somewhat longer life spans. Nevertheless population growth remained low due to high infant mortality rates. The impact of the Neolithic revolution was not as much on immediate population growth (even though it did have a long term impact on population growth) as on the material and spiritual development of the human race. It is widely regarded as the beginning of civilization.
Industrial revolution was another process of change. It was the process of substituting muscle power with machine power. It took place in the 18th century in Europe and is still happening in many parts of the world.
In many characteristics it has been similar to the Neolithic revolution: it increased production, it led to the use of resources that had been mostly unused until then and it improved the overall quality of life. It also led to changes in the structure of society. What was different was its impact on population growth. It was quick and easily noticeable. Advanced sanitation, hygiene and medicine led to longer life spans and declining death rates, with the birth rates remaining high. This resulted in a high rate of population growth that still continues in many countries.
The information revolution is the process of change that began in the second half of the 20th century in the developed countries of the world. It is the process of substituting ‘brain power’ with ‘machine power’. It leads to increased production and has the potential to create a more even distribution of the world’s population on the surface of the earth. It also has the potential to decrease the differences between the less developed and the highly developed nations of the world. Then again it also has the potential to increase those differences. It causes changes in the structure of society. Many of its impacts are still to be experienced.
Environmental Revolution means In view of some, a coming change in the adaptation of human to the rising deterioration of the environment. The Environmental Revolution will purportedly bring about sustainable interactions with the environment. Revolutions suggest overthrowing something, and indeed, what is involved is an overthrow of prevalent attitudes toward over economy and the environment. This does not have to be a violent revolution; it could take place so peacefully that it would take a future generation to look back and realize that a major revolution had occurred.
We can choose to undergo the changes necessary to achieve sustainability by planning properly and learning as we go, or we can ignore the signs of unsustainability and increase our impact on the environment by driving bigger cars ( and more of them), living in bigger houses, flying off to more vacations, and, in general, expecting to enjoy more of everything. And the developing world, as it tries desperately to catch up to our living standards, could make the same mistakes we are making, with devastating consequences because there so many more people there than in the developed world. If we choose to ignore the signs that our current practices are unsustainable, a different kind of environmental revolution will be thrust upon us by the inability of the environment to support an irresponsible human population.
In the carbon cycle, the key events are the complementary reactions of respiration and photosynthesis. Respiration takes carbohydrates and oxygen and combines them to produce carbon dioxide, water, and energy. Photosynthesis (6CO + 12H O + Light Energy C H O + 6O +6H O) takes carbon dioxide and water and produces carbohydrates and oxygen. The outputs of respiration are the inputs of photosynthesis, and the outputs of photosynthesis are the inputs of respiration. The reactions are also complementary in the way they deal with energy. Photosynthesis takes energy from the sun and stores it in the carbon-carbon bonds of carbohydrates; respiration releases that energy. Both plants and animals carry on respiration, but only plants and other producers can carry on photosynthesis. The chief reservoirs for carbon dioxide are in the oceans and in rock. Carbon dioxide dissolves readily in water.
Once there, it may precipitate as a solid rock known as calcium carbonate. Corals and algae encourage this reaction and build up limestone reefs in the process. On land and in the water, plants take up carbon dioxide and convert it into carbohydrates through photosynthesis. This carbon in the plants now has 3 possible endings. It can be returned to the atmosphere by the plant through respiration; it can be eaten by an animal, or it can be present in the plant when the plant dies. Animals obtain all their carbon in their food, and, thus, all carbon in biological systems ultimately comes from plants. In the animal, the carbon also has the same 3 possible endings. Carbon from plants or animals that is released to the atmosphere through respiration will either be taken up by a plant in photosynthesis or dissolved in the oceans.
When an animal or a plant dies, two things can happen to the carbon in it. It can either be respired by decomposers or released to the atmosphere, or it can be buried intact and ultimately form coal, oil, or natural gas (fossil fuels). The fossil fuels can be mined and burned in the future; releasing carbon dioxide to the atmosphere. Otherwise, the carbon in limestone or other sediments can only be released to the atmosphere when they are sub ducted and brought to volcanoes, or when they are pushed to the surface and slowly weathered away. Humans have a great impact on the carbon cycle because when we burn fossil fuels we release excess carbon dioxide into the atmosphere. This means that more carbon dioxide goes into the oceans, and more is present in the atmosphere. This causes global warming, because the carbon dioxide in the atmosphere allows more energy to reach the Earth from the sun than it allows escaping from the Earth into space.
Phosphorus has only one form, phosphate. This molecule never makes its way into the atmosphere; it is always part of an organism, dissolved in water, or in the form of rock. When rock with phosphate is exposed to water, the rock is weathered out and goes into solution. Plants get phosphorus from the soil, after the water washes it into the ground. Animals obtain their phosphorous from the plants they eat. Animals may also use phosphorous as a component of bones, teeth and shells. When animals or plants die, the phosphate may be returned to the soil or water by the decomposers. There, it can be taken up by another plant and used again. This cycle will occur over and over until at last the phosphorous is lost at the bottom of the deepest parts of the ocean, where it becomes part of the sedimentary rocks forming there.
Ultimately, this phosphorous will be released if the rock is brought to the surface and weathered. Two types of animals play a unique role in the phosphorous cycle. Humans often mine rock rich in phosphorous. For instance, in Florida, which was once sea floor, there are extensive phosphate mines. The phosphate is then used as fertilizer. This mining of phosphate and use of the phosphate as fertilizer greatly accelerates the phosphorous cycle and may cause local overabundance of phosphorous, particularly in coastal regions, at the mouths of rivers, and anyplace where there is a lot of sewage released into the water.
Local abundance of phosphate can cause overgrowth of algae in the water; the algae can use up all the oxygen in the water and kill other aquatic life. This is called eutrophication. The other animals that play a unique role in the phosphorous cycle are marine birds. These birds take phosphorous containing fish out of the ocean and return to land, where they defecate. Their guano contains high levels of phosphorous and in this way marine birds return phosphorous from the ocean to the land. The guano is often mined and may form the basis of the economy in some areas.
Nitrogen gas in the atmosphere is composed of two nitrogen atoms bound to each other. It is a pretty non-reactive gas; it takes a lot of energy to get nitrogen gas to break up and combine with other things, such as carbon or oxygen. Nitrogen gas can be taken from the atmosphere in two ways. First, lightning provides enough energy to “burn” the nitrogen and fix it in the form of nitrate. This process is duplicated in fertilizer factories to produce nitrogen fertilizers. The other form of nitrogen fixation is by nitrogen fixing bacteria, which use special enzymes instead of the extreme amount of energy found in lightning to fix nitrogen. These nitrogen-fixing bacteria come in three forms: some are free-living in the soil; some form symbiotic, mutualistic associations with the roots of bean plants and other legumes; and the third form of nitrogen-fixing bacteria are the photosynthetic cyanobacteria which are found most commonly in water.
All of these fix nitrogen, either in the form of nitrate or in the form of ammonia. Most plants can take up nitrate and convert it to amino acids. Animals acquire all of their amino acids when they eat plants or other animals. When plants or animals die or release waste, the nitrogen is returned to the soil. The usual form of nitrogen returned to the soil in animal wastes or in the output of the decomposers, is ammonia. Ammonia is rather toxic, but, fortunately there are nitrite bacteria in the soil and in the water which take up ammonia and convert it to nitrite. Nitrite is also somewhat toxic, but another type of bacteria, nitrate bacteria, takes nitrite and converts it to nitrate, which can be taken up by plants to continue the cycle. Then, to return the nitrogen back to the air, there is denitrifying bacteria in the soil which takes the nitrate and combines the nitrogen back into nitrogen gas.
The good and services provided by natural ecosystems are not easily seen in the market (meaning the market economy that normally allows us to place value on things) or may not be in the market at all. Thus, things such as clean air to breathe, the formation of soil, the breakdown of pollutants, and the like never pass through the market economy. People are often not even aware of their importance. Because of this, these things undervalued or not valued at all. The functioning of natural ecosystems provides services essential to human survival. Collectively, these services maintain the Earth in a state that can support life.
Ecosystem services maintain the atmosphere, provide clean water, control soil erosion, pollution and pests, pollinate plants, and much more. Consider the atmosphere. Terrestrial animals need air with the correct balance of gases, which includes at least 20% oxygen. Oxygen is provided by plants and algae through photosynthesis. So clearing vegetation and polluting the ocean may threaten the very air we breathe. Water is also essential for survival. The water cycle of rain and evaporation is partly controlled by vegetation. For example, forests can affect entire regional climates because they pump enough water from the soil to the air, causing more rainfall. Large-scale deforestation could cause serious drying of regional climates.
Richard T. Wright (2005) Environmental Science toward a Sustainable Future. Upper Saddle River, N.J. Pearson Prentice Hall 9th edition