Saturday, December 19, 2009

Human impact on the Natural Environment

The term "environment" means the surroundings of a living creature. It is an immediate surrounding which helps to sustains life. An ecosystem is according to the Millennium Report (2003) defined as “a dynamic complex of plants, animals and microorganism communities and the nonliving environment, interacting as a functional unit. Humans are an integral part of ecosystems.” Ecosystems are the planet’s life-support systems - for the human species and for all other forms of life. Humans have become powerful agents of global environmental change. It is obvious that changes in any single component of the earth’s system may affect the entire system.Environmental threats now violate national boundaries. Wind currents, rain patterns, rivers and streams carry pollutants hundreds or even thousands of kilometers from their source. The global environmental problems like climate change, ozone depletion, deforestation, loss of biodiversity threatens all nations. Ecological issues have become a central feature of international relations.


Human induced environmental changes

• Pollution of atmosphere, hydrosphere, and geosphere
• Global warming
• Deforestation
• Loss of ecosystems
• Reduced biodiversity and more.
• Each change triggers another.

Human population growth

It is the number one threat to the world's environment. Each person requires energy, space and resources to survive, which results in environmental losses. Currently, the world human population stands at just over 6 billion people and is increasing at a rate of 1.6% per year. The world’s population presently grows by about 250,000 people per day. Given the current rate of growth, the world’s population will reach 7 billion by 2010 and nearly 8.4 billion by 2025.Human population is rapidly rising beyond the earth's ability to regenerate and sustain with a reasonable quality of life. We are exceeding the carrying capacity of our planet. Over-population leads to: resource depletion, resource degradation, pollution and loss of biodiversity

Modernization of agriculture 

It has a greater harmful effect on the air, soil, water and biodiversity. Pesticides have several characteristics that cause extensive damage to ecosystems: high stability, high mobility and biological magnification. Bioaccumulation increases the concentration of a pollutant from the environment to the first organism in a food chain. Biomagnification increases the effects of pollutants in the environment through food chains. Salinization and water logging of soil is caused due to heavy irrigation practices. Too much of water used to irrigate only 18% of world’s cropland. Intensive agriculture practices leads to pollution from pesticide use, fertilizer run-off, nitrate buildup, salts and phosphates ( from livestock wastes, commercial inorganic fertilizers). Clearing of grasslands & deforestation to support grazing and urbanization lose wildlife and destroy habitats and decrease biodiversity.


Forests around the world being destroyed for lumber, for fuel and for agriculture. (e.g. "slash-and-burn" agriculture). Tropical rainforests are disappearing at an alarming rate. Destruction of forest impacts on all organisms that live there- increasing extinction rates. Soils become nutrient poor. Soil erosion results in soil loss and increased sediments in rivers, lakes and estuaries.


Overgrazing results in removal of vegetation and exposing of soil to wind and water erosion. Grasslands become unusable desert. High rates of topsoil erosion occur due to overgrazing.

Air pollution 

Pollution of air results from human activities such as burning fossil fuels (oil, coal, and gasoline) to create electricity and power automobiles, and manufacture industrial products such as chemicals and plastic. These human activities release waste products such as particulates, HC, CO2, CO, NO, NO2, SO3 -- source may be industrial, autos, etc. The increased carbon dioxide in the atmosphere contributes to the warming of the global climate, the so-called "greenhouse effect." In 1850, atmospheric carbon dioxide was about 280 parts per million (ppm). Today, it is about 350 ppm. Elevated CO2 means an increase in global temperature. Global Warming is increase in the average temperature of the atmosphere, oceans, and landmasses of Earth. Another human impact on the atmosphere has been depletion of the stratospheric ozone. Chlorofluoro-carbons used as coolants in air conditioners and refrigeration units destroy ozone when released into the atmosphere. Each 1% drop in stratospheric ozone is thought to increase human skin cancer rates by 4-6%. The United Nations Environment Program predicts a 26 percent rise in cataracts and non-melanoma skin cancers for every 10% drop in ozone. This translates to 1.75 million cases of cataracts and 300,000 more cases of skin cancer every year. Ozone is considered a pollutant at ground level. Breathing O3 affects both the respiratory and nervous systems, resulting in respiratory distress, headache, and exhaustion. The extra acidity in rain (acid rain) comes from the reaction of primary air pollutants, primarily sulfur oxides and nitrogen oxides, with water in the air to form strong acids (like sulfuric and nitric acid). The main sources of these pollutants are vehicles and industrial and power-generating plants.

Land Degradation 

It refers to loss of quality and productive capacity of soil. It includes the loss of organic matter, the reduction of vegetative cover and biodiversity, a general decline in soil life and fertility. Soil degradation results in compaction, erosion, a reduction in water holding capacity and increased salinization. Soil is getting thinner, “tired” and “worn out”. About 22%of all cropland degraded since 1945. One quarter of the world’s agricultural land has been severely degraded.
‘Soil is a living system’. A fertile soil is a living soil containing billions of living organisms in every cubic centimetre. Earth is not just our home. It is our mother provider and protector. A clean earth is the best inheritance, we can give our future generations.

Water Pollution 

Pollutants in water include a wide spectrum of chemicals   and pathogens. Many of the chemical substances are toxic. Pathogens can produce  waterborne diseases in either human or animal hosts. Alteration of water's physical chemistry include acidity, electrical conductivity , temperature, and eutrophication. Eutrophication is the  fertilization of  surface water by nutrients. Water-associated infectious diseases claim up to 3.2 million lives each year, approximately 6% of all deaths globally. The burden of disease from inadequate water, sanitation, and hygiene totals 1.8 million deaths.
Water is essential for life. There can be no life without water. ‘Water is life, do not waste it’

Threats to Biodiversity

Habitat loss and destruction is usually a direct result of human activity and population growth. It is a driving force in the loss of species, populations, and ecosystems. When the habitats become smaller, less food and shelter are available. As a result, species living in these habitats compete with each other and with humans for limited resources.
Alterations in ecosystem composition cause the loss or decline of a species. Introduction of exotic (non-native) species affect native species by eating them, infecting them, competing with them, or mating with them. Over-exploitation (over-hunting, over-fishing, or over-collecting) of a species or population can lead to its demise. Human-generated pollution and contamination can affect all levels of biodiversity. Global climate change can alter the adaptation of species and populations.
“Man has lost the capacity to foresee and to forestall. He will
end by destroying the Earth” - -Albert Schweitzer, quoted by Rachel Carson, in her Book  “Silent Spring”, (1962)

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