Final answer:
In 2011, the United Nations announced that the world's population reached 7 billion people, reflecting the rapid growth and the importance of studying demography for future population projections.
Step-by-step explanation:
In 2011, the United Nations announced that the world's population had reached a significant milestone of 7 billion people. This rapid increase in population size, occurring in just 12 years after hitting the 6 billion mark, demonstrated an exponential growth pattern. Demography, the study of populations, is an important field for understanding the implications of population changes. It considers factors such as fertility, mortality, and migration to assess population dynamics and future trends.
Looking ahead to 2050, population estimates by the United Nations and the U.S. Census Bureau suggest a further surge to approximately 9.4 to 9.7 billion people. Moreover, countries categorized by the United Nations Population Fund (2008) with high fertility rates, predominantly in sub-Saharan Africa, are anticipated to experience a tripling in population between 2011 and 2100, while those with low fertility rates may face declines.