Role of man in ecology

The man appeared late in the ma’s history, but was able to change the earth’s environment by its actions. Humans first appeared in Africa and they quickly spread throughout the world. Having unique mental and physical capabilities, humans were able to change the environment to meet their needs.

Early humans obviously lived in harmony with the environment but they began the first prehistoric agricultural revolution. The ability to control and use fire allowed them to modify or eliminate natural vegetation, and the domestication and herding of grazing animals resulted in overgrazing and soil erosion. The domestication of plants also led to the destruction of natural vegetation to make room for crops and the demand for wood, for fuel left bare mountain and exhausted forests. Wild animals were killed for food and destroyed as pests and predators.

While human population remained small and human technology modest, their impact on the environment was localized. As population increased and technology improved and expanded, however, more significant and widespread problems arose. Rapid technological advances after the Middle Ages culminated in the Industrial Revolution which involved the discovery, use and exploitation of fossil fuels as well as the extensive exploitation of the earth’s mineral resources. With the Industrial Revolution, humans began in earnest to change the face of the earth, the nature of its atmosphere, and the quality of its water. Today, unprecedented demands on the environment from a rapidly expanding human population and from advancing technology are causing a continuing and accelerating decline in the quality of the environment and its ability to sustain life.

Carbon dioxide

One impact that the burning of fossil fuels has had on the earth’s environment has been the increase of carbon dioxide in the earth’s atmosphere. The amount of atmospheric CO2 apparently remained stable for centuries, at about 260 ppm ( parts per million), but over the past 100 years it has increased to 350 ppm. The significance of this change is its potential for raising the temperature of the earth through the process known as the greenhouse effect. Carbon dioxide in the atmosphere tends to prevent the escape of outgoing long wave heat radiation from the earth to outer space. As more heat is produced and less escapes, the temperature of the earth increases.

A significant global warming of the atmosphere would have profound environmental effects. It would speed the melting of polar ice caps, raise sea levels, change the climate regionally and globally, alter natural vegetation, and effect crop production. These changes would, in turn, have an enormous impact on human civilization. Since 1850 there has been a mean rise in global temperature of about 1*C. Some scientists have predicted that rising levels of CO2 and other “greenhouse gases” will cause temperatures to continue to increase, with estimates ranging from 2* to 6*C by the middle of the 21^st century. However, other scientists who research climate effects and trends dispute the theories of global warming, and attribute the most recent rise to normal temperature fluctuations.