Environmental change is a continual process that has been in operation since the earth came into existence about 4600 million years ago. Since then, dynamic systems of energy transfer and material transfers have operated on a global scale to bring about gradual and sometimes catastrophic transformations of the lithosphere, atmosphere, hydrosphere, and biosphere. For most of the history of the earth, the agents of change have been the natural forces like volcanoes, earthquakes and natural elements of running water, wind, glaciers, sea-waves, plants and animals. About 4.5 million years ago, however, a new agent of change emerged in the form of hominids (ancestor of ape) culminating in the revolution of homo sapiens or modern humans, that are considered by many to be the most powerful generators of environmental change.
Environmental Degradation Causes
Man is the product of the earth. He is, however, a creator of the cultural landscape and a transformer of the physical landscape. In fact, human beings have dominated ecology since their emergence on the earth. Man has interacted with his physical environment right from the primaeval stage of human development and continues to do so even today in this age of space technology with greater vigour. With the advancement in science and technology, the frontiers of knowledge have expanded beyond the cosmic space and the environment of the earth has transformed beyond recognition. People, in increasing numbers, with their technological skills have placed their imprints upon the natural landscape and environment, transforming the physical surroundings to conform to their needs. In some instances, such as that of megacities, conurbations, and modern towns on land and seas, the human imprints may be so complete that the original landscape of nature has been totally wiped away and replaced by the man-made cultural environment.
About 10,000 BP ( Before Present), the Neolithic Period started. It was during this period that man domesticated plants and animals. The emergence of agriculture has been regarded as revolutionary. Obviously, it was a very important development in human history. The start of agriculture provided a more reliable food resource. This might have enabled the development of permanent settlements, and higher population to be supported. The beginning of agriculture played a dominant role in the development of human communities and resulted in significant environmental changes. The natural systems were transformed into agro-ecosystems. With this development, homo sapiens started to control the ecosystems more vigorously.
The domestication of plants and animals brought about substantial changes in the physical environment. The introduction of domesticated species provided a food source that supplemented natural plant and animal resources. In this sense, diversity of species increased, but as clearance of natural vegetation was undertaken to make way for arable fields, diversity of species at least locally decreased. Geomorphic and hydrological systems were also radically altered as cultivation replaced the growth of natural vegetation.
With the passage of time, apart from the expansion and intensification of agriculture, the most conspicuous development during the historic period was the Industrial Revolution in Britain in 1779. The industrial revolution led to industrialisation and urbanisation. This revolution brought about environmental changes not only in Europe and Asia, but also transformed tremendously the environment in America, Africa, and Australia. The Europeans did large-scale deforestation in these continents for the expansion and development of agriculture which brought about further changes in ecology and environment.
The extraction of minerals became imperative for industrial development. The extraction of minerals at a large scale, however, creates environmental changes in the immediate vicinity of the mining centres. Mining also results in a widespread change in soil, aquatic and atmospheric environmental quality at a distance which may be related to both extraction methods and mineral processing. Of particular significance is the use of fossil fuels in mineral processing and vehicular traffic that are contributing to the enhanced greenhouse effect. One of the major causes of changes in environmental quality is contamination by heavy metals such as lead, cadmium, and mercury.
Environmental Degradation Consequences
Increase in Greenhouse Gases: One of the most important causes of environmental degradation is the widespread use of fossil fuels. The use of fossil fuels is increasing the concentration of carbon dioxide in the atmosphere. The increase in greenhouse gases is the main cause of climatic change and the rise of sea level. Consequently, biosphere and hydrosphere are adversely affected.
Acidification: Acidification is damaging aquatic ecosystems. According to ecologists, acidification has damaged the marine and aquatic ecosystems in lakes and rivers. The fish stock in the rivers of India is declining at a faster pace.
Ozone Depletion: The presence of ozone in the atmosphere is particularly important because it filters out the incoming ultraviolet (UV) radiation and thus, acts as a screen against ultraviolet B (UV-B) radiation that can increase the occurrence of some forms of skin cancer, cataracts and other diseases of an eye.
Air, Water, Soil, and Noise Pollution: The quality of air, water, and the soil is depleting both in the urban and rural areas. The air and water-borne diseases in the country are increasing. The population of the mega and million cities are the worst affected. In the states of Punjab, Haryana, and western Uttar Pradesh, the quality of underground water has gone substantially below the consumption level. Same is the case in Bhopal, Delhi, Jaipur, Meerut, and Saharanpur.
The problem of Disposal of Waste Material: The rapid industrialisation and urbanisation are leading to huge quantities of domestic, industrial, and nuclear wastes. The industrial wastes consist of chemicals, detergents, metals, and synthetic compounds besides solid waste and garbage. The heavy metal chemical pollutes the water system which may be a threat to aquatic life and human health. In addition to urban and industrial wastes, nuclear fuel is becoming an increased nuisance. The nuclear waste contains radioactive isotopes which generate large quantities of heat. These radioactive elements remain in the atmosphere for many hundreds and thousands of years. The disposal of nuclear waste is, therefore, a serious danger to the biosphere.
Soil Erosion: Soil erosion is a universal problem. It is all the more serious in the tropical and sub-tropical countries like India. In India, the problem of soil erosion is a serious menace as about 6000 million tonnes of soil is being eroded annually. According to one estimate, about 80 million hectares is adversely affected by soil erosion, out of which over four million hectares are affected by ravines and gullies. Soil erosion affects not only the areas where the soil is removed but also the ecosystems and environment of the places where the eroded soils are deposited.
Salinisation: The application of chemical fertilisers in heavy doses in the irrigated parts of the country have salinised the rivers, lakes, ponds, and underground water-bodies. Consequently, many of the water-bodies and wetland habitats have suffered adversely and their fauna and flora have been damaged or disappeared.
Desertification: The causes of desertification are numerous. The over the interaction of humans in the form of overgrazing, deforestation, and encroachment of forests for agricultural land has increased the desert area and resulted in more desertification within the Thar Desert.
Deforestation: Deforestation is a cause and effect of environmental degradation. The density of trees in the Indian forests is decreasing at a faster pace. There is only about 22.5 per cent of the total reporting area under forest. Destruction of forests changes surface and air temperatures, moisture content, and reflectivity. Conversion of forests to grasslands, for example, increases surface temperature, raises air temperature above the treeless ground and therefore, increases the water-holding capacity of warmer air. As the wind moves and becomes hotter and drier, it tends to exert a drying effect on adjacent forests and agricultural lands.
Afforestation is the need of the day to keep the forests in a healthy condition. Moreover, social forestry needs to be developed in the community land and the degraded forest areas of the country.
Reduction in Biodiversity: The rapid growth of population in India, especially after Independence resulted in the cutting of trees and deforestation. A major setback of deforestation is the loss of biological diversity. Many of the medicinal plants and useful insects are already in danger.