Page 30 - bfw-APHG-1e

As noted earlier in this Module, there are good get infected. In the past, many people lived in rural
reasons why certain parts of the world are densely villages dispersed over a large area, which made the
populated. They tend to have conditions that humans spread of the disease more difficult. In addition, the
consider desirable. More and more people are living in increasingly dense population distribution is contrib-
cities worldwide because cities, particularly big cities, uting to the severity of losses from natural disasters
offer many amenities that people enjoy even though air such as floods and earthquakes because more people
quality may be worse, housing usually costs more, and now live in hurricane- and earthquake-prone areas,
traffic congestion is common. Fortunately, urban plan- such as the coastal areas of the United States.
ning and technology may help to reduce or even elimi- In this Module, we examined population distri-
nate some negative aspects of city life. For example, air bution at different geographic scales, from global to
quality in London has improved significantly over time local. We identified the four major population clus-
while its population has grown. ters and the sparsely populated areas on Earth.
Unevenness is a key characteristic of population dis-
Disease and Natural Disasters tribution regardless of the scale of analysis. This dis-
tribution pattern is shaped by a number of physical,
Population distribution and density may affect peo- social, and cultural factors. Population tends to be the
ple’s health and vulnerability to natural disasters. most dense where the terrain is level, the climate is
Infectious diseases may spread faster in densely pop- mild and humid, the soil is fertile, mineral resources
ulated areas. For example, malaria is a major killer are abundant, and the sea is accessible. Population
in tropical African countries such as Gambia. Malar- tends to thin out with excessive elevation, aridity,
ia is caused by five types of parasite, which spread coldness, ruggedness of terrain, and distance from
through mosquito bites. One contributing factor is the coast. The distribution and density of population
that more and more people in African countries now have social, economic, political, and environmental
live in crowded cities and towns so more people may implications.

Module 7 Review

7-1 How is population distributed around the ound the 7 -3 W ha t ar e the thr ee methods f or calcula ting
-1
7
7-3 What are the three methods for calculating
w is popula
Ho
tion distribut
ed ar
world?
population density?
world? population density?
• Population distribution is highly uneven at global, • Arithmetic or crude population density refers to the
regional, national, and local scales. average number of people per unit area of land.
• There are four major population clusters in the world, • Physiological density is the ratio of population to
but much of Earth’s surface is sparsely populated. arable land (i.e., land suitable for agriculture). It is
• Population size and land area by country vary a good indicator of the pressure that the population
greatly. The top 10 countries in terms of population exerts on the land resource and agriculture.
will change because their populations are growing at • Agricultural density is the average number of farm-
different rates. ers per unit area of arable land. It reflects the labor
intensiveness of agriculture.
7
-2
7-2 What factors influence population tion
t fac
t
e popula
ors influenc

W
ha
distribution? 7-4 What are the consequences of population
distribution?
7-4
What are the consequences of population

distribution and density?
• A number of physical, cultural, and economic factors distribution and density?
have shaped the population distribution patterns on • Population distribution and density can affect eco-
Earth. nomic development, political representation, the
• The key factors that affect population distribution environment, and human health and vulnerability
patterns may depend on the scale of analysis. to natural disasters.
Module 7 Population Distribution and Its Consequences 19
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