key issue two: where has the world’s population increased?
TRANSCRIPT
Key Issue Two: Where has the world’s population increased?
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Geographers most frequently measure population change in a country or the world as a whole through three measures: Natural increase rate The percentage by which a population grows in a year
(excludes migration)
Subtract the CDR from CBR (after converting the two measures from numbers to percentages)
Crude birth rate (CBR) The number of births per 1,000 population
Crude death rate (CDR) The number of deaths per 1,000 population
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The world NIR during the first decade of the twenty-first century is 1.2, meaning that the population of the world was growing each year by 1.2 percent.
The world NIR is lower today than its all-time peak of 2.2 percent in 1963, and it has declined sharply during the past decade.
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About 80 million people are being added to the population of the world annually.
That number represents a decline from the historic high of 87 million in 1989.
The number of people added each year has dropped much more slowly than the NIR because the population base is much higher now than in the past.
Very small changes in the NIR dramatically affect the size of the population, because the base population from which we drive the percentage is so high.
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The rate of natural increase affects the doubling time, which is the number of years needed to double a population, assuming a constant rate of natural increase.
For example, if the 1963 NIR of 2.2 continued through the twenty-first century, it would have produced a total population of more than 50 billion in 2100. On the other hand, should the NIR immediately decline to 1.0, doubling time would stretch out to 70 years, and world population in 2100 would be 15 billion.
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Virtually 100 percent of the natural increase is clustered in LDCs. The NIR exceeds 2.0 percent in most countries of Africa, Asia, Latin
America, and the Middle East; whereas it is negative in Europe, meaning that the population is declining in this region.
About 2/3 of the world’s population growth during the past decade has been Asia, with the remaining 1/3 divided about equally among sub-Saharan Africa, Latin America, and the Middle East.
Regional differences in NIRs mean that most of the world’s additional people live in the countries that are least able to maintain them.
To explain the differences in growth rates, geographers examine regional differences in fertility and mortality rates.
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The world average is currently around 1.5%. Where are countries
with the highest NIRs?
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How does the map of Crude Birth Rates (CBRs) compare to the distribution of NIRs?
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Geographers also use the total fertility rate (TFR) to measure the number of births in a society.
The TFR is the average number of children a woman will have throughout her childbearing years (roughly ages 15 through 49).
To compute the TFR, scientists must assume that a woman reaching a particular age in the future will be just as likely to have a child as are women of that age today.
Therefore, the CBR provides a picture of a society as a whole in a given year, whereas the TFR attempts to predict the future behavior of individual women in a world of rapid cultural change.
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The world average is currently around 2.7. Where do we see the highest rates? Lowest?
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In addition to the CDR, two other measures are useful: infant mortality rate and life expectancy.
The infant mortality rate (IMR) is the annual number of deaths of infants under 1 year of age, compared with live births (usually expressed per 1,000 births rather than by percentage).
In general, the IMR reflects a country’s health-care system.
Lower IMRs are found in countries with well-trained doctors and nurses, modern hospitals, and large supplies of medicine.
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Where are the highest IMRs? The lowest? Why does the United States have a higher IMR than that of Canada and Western Europe?
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Life expectancy at birth measures the average number of years a newborn infant can expect to live at current mortality levels.
Where is life expectancy most favorable? Least favorable?
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Similarities in measures?
MDCs have lower rates of natural increase, crude birth, total fertility, and infant mortality, and have higher average life expectancies.
LDCs have higher rates of natural increase, crude birth, total fertility, and infant mortality, and have lower average life expectancies.
Differences in measures?
The CDR does not follow the familiar pattern listed above.
The combined CDR for all LDCs is actually lower than the combined rate of all MDCs.
Why? Take a look at the following map…
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