# X INTRODUCTION

How do the projections for the world and for LDCs and MDCs compare with those previously produced? Figure 2 compares this year's projections with the previous set (1990-91). For MDCs, there is no distinguishable difference between the projected populations. In the case of the LDCs projections, this year's projection is, from the early part of the 21st century onward, increasingly below the previous projection. This reflects the Impact of AIDS, which increases the number of deaths and reduces the number of births. For the world as a whole, the projections differ to the same extent as the LDC projections differ.

When growth rates for major world regions are compared, striking differences become apparent. The continent with the highest growth rate is Africa with an annual rate of 2.9 percent in the early 1990s, about six times the 0.5 percent annual growth rate of Europe (which includes the former U.S.S.R. countries). Growth rates in the Americas, in Asia, and in Oceania are intermediate; at 1.5, 1.8, and 1.6 percent, respectively, they are close to the world's average. At these growth rates, the population of Africa would double in approximately 25 years, while Europe would double in 140 years.

One of the consequences of such large differences In population growth rates is a changing distribution of the population over the continents. Currently, Asia has 59 percent of all people; Europe, 15 percent; America, 14 percent, Africa, 12 percent, and Oceania, 1 percent. Over time, Asia's share is projected to remain fairly stable, but Europe's share will almost be halved and Africa's share more than doubled. Figure 3 shows the distribution of the worid's population at three different points in time.

Because Asia is so large and diverse, disaggregation of its populations by subregions is more illustrative of the differences in population growth rates. South Asia, which has 1.24 billion people (23 percent of the world population), has an estimated growth rate of 2.0 percent in 1992, while East and Southeast Asia, which include China and contains 1.85 billion people (34 percent of the world population), had a lower rate of 1.4 percent. South Asia is growing annually by 25 million, East and Southeast Asia by 27 million persons. By 2025, the growth rates are projected to decline to 1.1 percent and 0.9 percent, respectively. Even with these lower rates, 23 million people will be added in South Asia each year and 17 million in East and Southeast Asia because of their large projected base populations of 2.05 billion and 2.54 billion. Southwest Asia, which consists mostly of Middle Eastern countries, has a much smaller number of people, 143 million, but is growing at a faster rate than the other two regions, with a growth rate of 2.9 percent in 1992. It is projected to lower its growth rate to 1.6 percent by 2025, but will by then have more than doubled Its population to 293 million.

In Africa, more homogeneity is found among the East, West, and North subregions. The fastest growing subregion is East Africa with a growth rate of 3.0 percent in 1992, followed by West Africa with a growth rate of 2.9 percent. North Africa, has begun to lower its growth rate but still has a growth rate of 2.5 percent, which is projected to diminish to 1.3 percent by 2025. Even though East Africa's growth rate is projected to start declining immediately, by 2025 it will still have a growth rate of 1.9 percent, and will add 14 million persons a year. In West Africa, the growth rate is projected to decrease to 1.7 percent in 2025, but will still be adding 9 million persons each year. These differences In growth rates are the outcome of assumed trends in fertility and mortality (discuss'<sup>4</sup> below).

Oceania has a growth rate of 1.6 percent in 1992 and is projected to lower its rate to 0.6 percent by 2025. Because of Its small population (0.5 percent of the world's total) its impact on world demographic trends is triviaL