Some 2,000 years ago, the human population was 250 million. It rose to 500 million in 1650. In 1820, it doubled to 1 billion within 170 years. In the next 110 years, it again doubled to two billion in 1930. However, the major increase in the population was observed in the second half of the 20th century. The population doubling time narrowed to its maximum extent. The population was four billion in 1975, five billion in 1987 and six billion in 1998, respectively. If the same growth rate persists, the world population will be 10 billion in 2050.

It is no denying the fact that the world population is not distributed uniformely across the globe. A great proportion of the gobal population is concentrated in the northern hemisphere while in the sourthern hemisphere, it is only a fraction of the total world population.

South East Asia has the major concentration of the population. China, the most populated country of the world is here in this region. Japan and Korea are the other contributors. One quarter of the world population resides here. Out of the total population, 30 per ecnt are city dewellers on the eastern coasts.

The 70 per ecnt people live in the countryside growing crops for their own sustenance as well as for the city dwellers. Beijing, Shanghi and Tokyo are the most populated cities of the region.

South Asia is the second most populated region of the world. India with a population of about one billion is the highly populated country of the region. Pakistan, Bangladesh and Sri Lanka also contribute significantly in the total population of the region. Considerable population of the region is concentrated in the valleys of Indus, Ganges and Brahmputra. Total population of the region is nearly 1.5 billion.

Total population of Europe is 729 million. Here are more city dewellers about 70 per cent owing to intensive industrialization. France, Germany, Belgium, Belarus, Ukraine, UK and Poland are the major contributors to the population of the region. About four billion of the world population live in Eurasia.

North America is the fourth population concentration of the world. Botson, Philadelphia, New York, Baltimore and the South Eastern Canada are the thickly populated areas. Chicago, Detroit, Cleveland, Los Angeles, San Francisco and San Diego have minor contribution in the total population.

The combined population of South America, Africa and Australia is less than that of India alone. In these continents, there is much liveable space as population density is much less as compared to other continents.

Every year, there is net addition of 90 million people in the world population. As 177 million babies are born every year while 86 million people die during this period. This increase in population is alarming. Currently the world is facing a number of challenges owing to this population explosion.

As the population increased to a greater extent, its food and fiber requirements also mounted to meet its diversified needs. To provide food to rapidly increasing population, more and more forests were cut down and areas were cleared to bring it under plough. The extensive deforestration put forward a number of problems. Soil erosion, disturbance of oxygen cycle, depletion of soil fertility and loss of bio-diversity are a few to name.

It is a fact that industrial revolution facilited man’s life but it has serious consequences. Emission of green house gases that is carbon dioxide, methane, chloroflorocarbons etc.from industries has led to the problem of globing warming. It is said that an increase of 2-3 0C in the global temperature will cause the melting of ice caps.

If it happens, the sea level will rise and will inundate the low lying areas. It will result in the major reshift of the ecosystems. Another cause of atmosphere deterioration is the acid rain. Sulfur dioxide and nitrogenn dioxide released by the industries into atmosphere on reaction with water vapours form acids.

Sulfuric acid and nitric acid cause stunted forest growth, enhance the process of acidification in seas resulting in loss of marine life and stimulate corrision of buildings and monuments. Depletion of ozone layer due to increase in green house gases particulurly chloroflorocarbons has opened the eyes of the environmentalists and environment protection organisations. The ozone hole obsrved on the Antarctica is an agonizing news. Ozone layer infilterates the ultravoilet rays. The ultravoilet rays are harmful in case these reach on earth surface. These will stimulate skin cancers among the human beings.

It is beyond an iota of doubt that the world is facing the problem of water shortage. Water is a renewable source but its excessive use in agriculture and indusrties and wastedul domestic use has created a problem of water shortage. Water is now a contentious issue among the nations. Wrangling over building headwrok over Tigris and Euphrates between Turkey and Iraq , between Israel and Jordon over Yarmuk tributory and between Syria and Israel over Golan Heights water are the relevant examples. The process of desertification is increasing. Removal of forests, uncontrolled grazing, scanty rainfall and over cultivation of land are the factors to be cited in this regard. In areas where precipitation is scanty and temperature is high like Pakistan, the twin problems of salinity and waterlogging are rampant due to high evaporation rate. The cultivated land is reduced to greater extent due to these twin problems.

In arid and semi-arid regions, erosion is another factor of deterioration of the soil. Wind and water erosion has also resulted in a considerable reduction of the cultivated area. Rapid urbanization, establishment of industries and means of communications, roads, railways, airports etc. have also reduced the space under plough.

The most serious problem is the disposal of solid wastes. In developing countries; these wastes are thrown in open spaces. Vermin multipy and methane gas emitted in the backdrop of rottening of these wastes detrimental for human health and also cause deterioration of atmosphere. In the developed countries, landfills are used. But due to less space, these countries are facing a challenge regarding disposal of wastes. Dispoal of radioactive materials is the most daunting challenge.