INTRODUCTION

Demography is the study of human populations. It is an important part of sociology and the other social sciences because all persisting social aggregates- societies, states, communities, racial or ethnic groups, professions, formal organizations, kinship groups, and so on-are also populations. The size of the population, its growth or decline, the location and spatial movement of its people, and their changing characteristics are important features of an aggregate whether one sees it as a culture, an economy, a polity, or a society. As a result some anthropologists, economists, historians, political scientists, and sociologists are also demographers, and most demographers are members of one of the traditional social science disciplines [4].the beginning of the 21st century demographic factors have become a crucial determinant of global security. They steadily and dynamically change the formal as well as contextual aspect of security issues. Some contemporary demographic trends have a specific character, and their diversity grows.

Demographic prognoses are the basis for the contemplation about future social developments.

In some areas population growth will exacerbate environmental degradation, competition for scarce resources, vulnerability to disease, support for extremist political and religious movements, and sometimes violent conflict. Chronic high fertility rates in developing nations with narrowly based elites and weak institutions are particularly vulnerable.from rural to urban areas, or legally or illegally across national boundaries, will evoke tensions, discrimination, and violence; strain health-care delivery systems; and contribute to disease outbreaks, particularly in receiving areas.risk is high that some allies in the developing world will be destabilized by migratory population flows.fertility rates between ethnic groups with mixed settlement patterns and historical enmity within countries and between neighboring countries will exacerbate instability and conflict, which could ultimately change the balances of power in some regions.in the structure of the world population are the subject of attention of many scientists as well as world organizations. Since the population changes have also economic and social effects, it is evident that in the period of rapid population changes there is a need and significant demand for information and data concerning the future development of population and its parameters.

1. DEMOGRAPHIC FORECASTS

research object of demography is population. Population cannot be taken as a static element; rather it is characterized by a strong dynamics in quantity, structure, spatial distribution and other features. At the same time, changes of various features are, as a general rule, mutually interconnected in a chain way, and they account for a characteristic and vital process of each population.' own dynamics involves a great amount of processes that at various geographical levels act in different ways and incorporate specific problems. Population growth requires a parallel growth of supplies and services to provide for basic human needs., population growth exerts pressure on the employment market, GDP production and social stability [1].qualified decision in the sphere of economy, social affairs, employment, education, health care and accommodation cannot be made without qualified, properly structured, variable and prompt demographic information. The importance of demographic information further increases with the significant changes in reproductive behavior leading to a transformation of the population structure as well as family and household composition. Apart from information about the past and current population development, information about expected development is needed for decision processes.

In 2003 the UN published a prognosis of the world population, which in contrast to the previous long-term one for the period up to 2150, has a significantly longer time horizon - up to the year 2300. But it is necessary to say that the results for such a long-term prognosis have to be taken with a grain of salt. As more useful we can take results for the period up to the year 2050 [1].prognosis is based on the finding that the population increase of the developing countries caused by high birth rate has slowed down, and it is proposed that it will be gradually slowing down in the next period. Thus it will be comparable to the situation in the highly developed countries, where, on the contrary, the prognosis supposes an increase in the contemporary low birth rate. Everywhere, an increase in the average life expectancy is expected.the UN projection the world population is supposed to be 8.92 billion people by 2050.world population will reach its maximum in 2075 with 9.22 billion, which will be followed by a slow decrease, and in 2300, the size of the world population should be stabilized at 8.97 billion. This prognosis of population growth is derived from the so called medium or, in other terms, optimal estimation. The justification of the statement concerning the achievement of the world population size at this level comes out from indicators of maximum, or in other terms, a relative year to year increase in the world. While the population increase of 2.19 % per a year achieved its climax in 1963, in the contemporary period this increase is around 1.14 %. At the same time in 1989 the maximum in-between year increase of the world population achieved 88 million people.experts claim that even a small change in birth rate could alter significantly the prognosis for the year 2300. An estimate of nine billion is therefore only a medium parameter based on the assumption that each family in the world will have two children on average. If the average number of children per family is one eighth lower, there will only be 2.3 billion people. Although it is impossible to exclude both possibilities, the UN does not reckon with them. Birth rates may change in different regions differently, but overall there is an assumption that regions and countries will show the same demographic trends on a long-term horizon, but the particular levels of development will be reached in a different period of time.with the global population changes it is important to monitor regional population trends. There are 6.9 billion people in the world. Of those, 1.22 billion - that is, 17.9 % of the world population, live in developed countries and 5.69 billion (82.1 % of the world population) live in developing countries. But according to the UN, the prediction of the world population's increase by the year 2050 differs. Globally, there will be an increase of approximately 2.5 billion but most of this increase will take place in the least developed countries (namely Africa). The developing countries have "a kind of delay" of 75 years in their demographic development, compared to developed countries, and the process of demographic revolution in developing countries should be finished in these countries in some 50 years. However, population growth as such will continue for another 50 years. It means that a final solution to this problem can be expected in the second half of the 21st century.very problematic region in this respect is Africa where the population growth today is 2.9 %. Other problematic regions include Latin America and South Asia. This last region had 2.2 billion people at the end of the 20th century, which is the same number as the world population in 1950 [3]different development is also expected in certain subregions within the larger regions (World Population to 2300). For instance: Three African regions - east, middle and west Africa will have reached an unusually high increase comparing to other regions by the year 2100. In case of this region's countries there is an expected increase in the years 2000 - 2050 of more than 200 % (Chad - 282 %, Uganda - 250 %, Congo - 245 %, Somalia - 240 %, Mali - 230 %).Asian regions there is an expected steeper increase in the West, a slower one in the East (Oman - 218 %, Saudi Arabia - 185 %, Pakistan - 138 %, Nepal - 110 %, India - 58 %, Bangladesh - 57 %). By the year 2100 Asia will be 2.2 times more populated than Africa, comparing to today's 4.5 on the side of Asia.America and the Caribbean, as the most homogenous regions, will follow relatively parallel trends in natality and probable life expectancy (Paraguay - 155 %, Nicaragua - 122 %). North America as the only region will not reach the so called under the increase-level value by the year 2050, mainly due to migration.Europe, similarly as in Asia, a greater increase is expected in the West, and a lower one in the East. Eastern Europe stands out with its low values of life expectancy, and even in long- term predictions, it will not reach the level of other regions.present more than 60 % of the world population (3.8 billion) live in Asia with China and India only having 37 % of the world population (2.5 billion), followed by Africa with 14 % (1 billion), Europe with 11 % (731 mil.), North America with 8 % (514 mil.), South America with 5,3 % (371 mil.) and Australia and Oceania with 0,3 % (21 mil.).4.83 billion people (70.5 % of the world population) live in 20 countries of the world. The European Union has 501 million people which accounts for only 7.4 % of the world population. In case of the most populated countries of the world, it is possible to see significant differences in population development in the future. In the year 2050 there will be a population increase in, first of all, less developed countries of the world. India will become the most populous country, replacing China. That means that in the period of 100 years (1950 - 2050), we will witness the most significant absolute increase of population; more than 1.3 billion of the population.