Neither energy nor matter can be created or destroyed. No one, howsoever advanced technologically, can create something out of nothing nor can anything be so discarded as to become nothing.
A constant flow of materials is needed to maintain living beings, a society, or an economy which must come from somewhere, whereas a continuous stream of wastes discarded has to go somewhere, The total amount of matter present on our planet is fixed except for cosmic particles entering and some gases leaving from outer atmosphere. This has been so throughout the known history of our planet. The elemental composition of earth’s atmosphere, hydrosphere and the lithosphere is fixed, stable and known.
The enormous changes which take place every day involve changes in the state, mix and distribution of materials on earth. Plant communities grow or die or burn away. Large quantities of water evaporate, condense and rain back to earth’s surface. Volcanos erupt, emit lava, ash and gases, create new islands or bury cities.
Each year man extracts billions of tons of materials and fuels from earth, transforms them chemically creating new molecular combinations which never existed before. All these activities require energy, which comes only from just two sources the incoming solar radiations and the residual heat of earth’s core. Fusion energy is the only source of energy which man has not been able to harness till date.
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In other words, as far as matter is concerned, our planet is nearly a closed system – nothing enters or leaves it. However, for energy, earth is an open system. It regularly receives large amounts I of energy from sun, much of which has to be re-radiated back to space in order to maintain a controlled temperature.
Therefore, mankind’s immediate environment, the planet earth, is limited in size and space as well as in its material resources. There is a constant entry of energy into the system as solar radiations, however, material resources of our planet are fixed in quantity and have to be used again and again in a cyclic fashion.
(1) Limitations of Non-Renewable Resources:
Most of our mineral deposits and deposits of fossil fuels are non-renewable in nature. Long periods of geo-chemical and biological activity have collected these materials to form concentrated deposits. We may not irreversibly consume these materials but their exploitation does scatter them in a highly dispersed state in the environment. With a sophisticated technology, we may recover these materials from their highly dispersed state. But the cost shall be enormous and the effort could be economically non-viable.
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Similarly we can use the deposits of fossil fuels only once. Once they are depleted there is no way to reform them. Thus continued over-exploitation shall exhaust many of our valuable deposits which took millions of years to form. They cannot be duplicated within the human scale of time. They require time on geologic scale to form (Kesler, 1976).
(2) Limitations of Renewable Resources:
Most of the biotic resources which are developed as a result of only recent photosynthetic activity of green plants are renewable in nature. The biosphere (minus man) constitutes an excellent life-support system which can fulfill all human needs. But its size and productivity is limited by availability of water, nutrients and environmental conditions.
Though an enormous quantity of water is present on our planet, for fresh-water life depends largely on precipitation, which too is available only in a finite quantity annually. Its uneven distribution over earth’s surface has caused large surface area to become infertile deserts.
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A large part of earth’s surface is too cold or rocky for any productive use, whereas a large area has to be devoted to forests and wild-life which due to their obvious importance cannot be curtailed beyond certain limits. This leaves only a limited area at our disposal for agriculture and pastures. No wonder during the past twenty years the area used for food grain production has not increased at all in spite of earnest human efforts to do so.
Growing more and more from the same crop fields involves expensive use of fertilizers, energy inputs, irrigation and high yielding varieties. Global livestock and fisheries resources can also not be expanded beyond certain limits. Products of forestry and wild-life, too, cannot be extended indefinitely. It is only upto a limited extent that resources of biosphere can be safely exploited. Over- exploitation tends to damage the biotic system and thereby the overall productivity. It could cripple the very resource base which is so important to our existence.
Thus like non-renewable resources renewable resources are also finite. They cannot be stretched beyond a certain limit. With careful management this limit can be enlarged. However, there is an ultimate line within which mankind shall have to confine itself. (Dorfman, 1985).