It is very difficult to predict the future of a population. The factor that affects future population growth such as birth rate, fertility rate and death rate can change dramatically.
The world's population growth is now 1.76 per cent annually i.e., more than 65 million people are being added every year. Three quarters of world population lives in the less developed countries, with more than half of the world's
population lives in the less developed countries with more than half of the world's population living in Asia alone, on the other hand the population of the developed countries are growing at a slower rate of 0.6%.
The less developed countries are growing 3-4 times faster with Asia and Africa taping the lead. The worlds are experiencing extreme growth of population, resulting in severe impediments of environmental degradation, health hazards and over crowd in the metropolitan cities. The extreme growth in population is termed as "population explosion".
It is most marked in the underdeveloped and industrially less advanced countries. It is a worldwide phenomenon and is staggering go and unpredictable in its international and domestic repercussions. However, its intensity varies from area to area.
Concentration of population in the world countries, China ranks first (1.29 billion) followed by India 1.028 billion. The growth rate of population and its distribution is uneven and varies from continent to continent and country to country.
Water bodies cover about 71% of the Earth area. Out of the total landmasses, 20% land is covered by mountains, where concentrations of population are very low. Similarly, many areas of the world have cold and hot deserts. The Antarctica continent and Greenland Island are covered by perpetual snow.
However, the high concentration of population is limited to the regions of South and South-East Asia, Brazil, Central Europe and Eastern-North America (North-East United States and South-East Canada).
The growth rate in the population also varies from the Asian countries to the European countries. Many of the countries of Europe continents are experiencing demographic transition. The United Nations (UN), an accepted authority on population level and trends, estimates that the world population reached 6 billion in 1999, and is increasing annually by more than 77 million persons. The rate of increase, 1.3 per cent per year, has fallen below the peak rate of 2 per cent per year attained by 1970. By the late 2040s, the UN estimates, the growth rate will have fallen to about 0.64 per cent annually, at which time more than 50 countries will experience negative growth.
This unprecedented surge in population, combined with rising individual consumption of food, water and natural resources has begun to strain Earth's capacity to sustain human life. Demands for water are draining supplies from aquifers (layers of permeable rock, sandy gravel that serve as repositories of water) and other water sources.
Demand for fish, a food staple in many areas of the world, is contributing to the depletion of fish stocks around the world. Human activities that cause pollution and encroach on natural habitats are responsible for the greatest extinction of plant and animal species since the dinosaurs disappeared about 65 million years ago.
Meanwhile, global warming an increase in Earth's surface temperature caused largely by the burning of fossil fuels has begun to change Earth's climate in ways not yet fully understood. In short the growth in human population and the scale of human activities appear to be redirecting the natural course of our planet.
Human population growth may be seen to be at the root of virtually all of the world's environmental problems. As the number of people increases, more pollution is generated, more habitats are destroyed, and more natural resources are used up. Even if new technological advances were able to reduce the environmental impact that each person had, as soon as the world's population size doubled, the earth would be no better off than before.