Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: http://guidesbyjulie.blogspot.com/ IB World Geography September 14, 2009 Population Demographics, Cont. C limates Climates Dry Lands-Areas too dry for farming cover approximately 20% of Earth’s land surface. Deserts generally lack sufficient water to grow crops, although some people survive there by raising animals such as camels, animals, that are adapted to their climate. Dry lands may contain natural resources notably, much of the world’s oil resources, reserves. reserves Wet Lands-Lands that receive very high levels of precipitation may also be inhospitable for human occupation. These lands are located primarily near the equator. The combination of rain and heat rapidly equator depletes nutrients from the soil, thus hindering agriculture. In seasonally wet lands, such as those in Asia, Southeast Asia enough food can be grown to support a large population. Cold Lands-Much of the land near the North and South poles is perpetually covered with ice or the ground is permanently frozen (permafrost Few animals can survive the extreme cold, and few humans live there. permafrost). permafrost High Lands-Relatively few people live at high elevations. We can find some significant exceptions, especially in Latin America and Asia. Asia Population Rates The Natural Increase Rate (NIR) is the percentage by which a population grows in a year The world’s NIR year. during the first decade of the twenty-first century is 1.3%. The NIR is lower today than at its all-time peak of 2.2% in 1963. However, the NIR during the second half of the 20th century was high by historical standards. The number of people added each year has dropped more slowly than the NIR, because the population base is much higher than in the past. The rate of natural increase affects the doubling rate which is the number of years needed to double a rate, population. When the NIR was 2.2% back in 1963, doubling time was 35 years. Virtually 100% of the natural increase is clustered in LEDCs. To explain these differences in growth rates, geographers point to the regional differences in fertility and mortality rates. Crude birth rate (CBR) is the total number of live births in a year for every 1,000 people. The highest CBR are in sub-Saharan Africa and the lowest are in Europe Geographers also use the Total Fertility Rate (TFR) to subAfrica, Europe. measure the number of births in a society. The TFR is the average number of children a woman will have throughout her child-bearing years (15-49). The TFR for the world as a whole is approximately 3. The TFR childexceeds 6 in many countries of sub-Saharan Africa, compared to less than 2 in nearly every European country. Crude death rate (CDR) is the total number of deaths in a year for every 1000 people. Two useful measures of mortality in addition to the CDR are the Infant Mortality Rate (IMR) and Life Expectancy The IMR is the Expectancy. annual number of deaths of infants under one year of age compared with total live births, usually age, expressed as the number of deaths per 1,000 births rather than a percentage. IMR exceed 100 in some LEDCs. In general, the IMR reflects a country’s healthcare system. http://guidesbyjulie.blogspot.com/ IB World Geography September 14, 2009 Population Demographics, Cont. L ife Life Expectancy at birth measures the average number of years a newborn infant can expect to live at current mortality levels. Babies born today can expect to live into their late 70’s in Western Europe, but only into their late 40’s in many Sub-Saharan countries. Demographic Transition Stages While population rates vary among countries, a similar process of change is operating in each country. This process is known as the Demographic Transition This transition has four stages, and barring a Transition. catastrophe such as a nuclear war, it is irreversible. irreversible Stage 1: Low Growth Most of humanity’s existence upon Earth can be characterized by Stage 1 of demographic transition. Crude birth and death rates varied considerably from year to year, and from region to region, but over the long term, they were roughly comparable at very high levels. Between 8000 B.C. and A.D. 1750 Earth’s human comparable, 1750, population increased from approximately 5 million to 800 million. The burst of population growth around 8000 B.C. was cause by the Agricultural Revolution Despite the Revolution, the human population remained in Revolution. Stage 1 of the demographic transition because food supplies were still unpredictable unpredictable. Stage 2: High Growth For nearly 10,000 years after the Agricultural Revolution, world population grew at a modest pace. After around A.D. 1750, the world’s population suddenly began to grow 10 times faster than in the past. In Stage 2 2, the CDR suddenly plummets while the CBR remains roughly the same as in Stage 1. plummets, Some demographers divide Stage 2 into two parts. During the second part the growth rate begins to slow part, slow, although the gap between births and deaths remains high. Countries entered Stage 2 of the transition after 1750 as a result of the Industrial Revolution The result of this transformation was an unprecedented level of Revolution. wealth, wealth some of which was used to make communities healthier places to live. Countries in Europe and America, North America entered Stage 2 of the transition about 1800, but Stage 2 did not diffuse to most countries in Africa, Asia, and Latin America until around 1950. The late 20th century push of countries into stage 2 was caused by the Medical Revolution Improved medical Revolution. practices suddenly eliminated many of the traditional causes of death in lesser-developed countries and enabled more people to experience longer and healthier lives. Stage 3: Moderate Growth A country moves from stage 2 to 3 in the demographic transition when the CBR begins to drop sharply sharply. th European and North American countries moved from Stage 2 to 3 in the early half of the 20 century. Most countries in Asia and Latin America have moved to Stage 3 in recent years, while most of Africa remains in 2. children. Stage 2 A society enters Stage 3 when people choose to have fewer children Medical practices introduced in Stage 2 societies greatly improved the probability of infant survival but many survival, years elapsed before families reacted by conceiving fewer babies. Economic changes in Stage 3 societies http://guidesbyjulie.blogspot.com/ IB World Geography September 14, 2009 Population Demographics, Cont. also induce people to have fewer offspring Farmers often consider a large family to be an asset. In offspring. contrast, children living in cities are generally economic assets. Stage 4: Low Growth A country reaches Stage 4 when the CBR declines to the point where it equals the CDR The condition is called CDR. Zero Population Growth (ZPG). Demographers more precisely define ZPG as the Total Fertility Rate that results in a lack of change in the total population over a long term. A TFR of approximately 2.1 produces ZPG ZPG, although a country that receives many immigrants may need a lower TFR to actually achieve ZPG. Most European countries have reached Stage 4 of the demographic transition. The U.S. has moved slightly above ZPG since 2006. The U.S. is in a unique position, considering it is a modern, industrial power, and it has the ability to replenish its population. Due to the influx of immigrants and the tradition of marriage and immigrants, childbirth, the U.S. once again is in a positive position for maintaining its growth. Several Eastern European countries, most notably Russia have negative natural increases. Russia, As memories of the Communist era fade, Russians and other Eastern Europeans may display birth and death rates more comparable to those in Western Europe. Alternatively, demographers in the future may identify a S tage 5th Stage of the demographic transition. This 5th stage will be characterized by higher death rates than birth rates, decline. rates and an irreversible population decline ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online