The Ecology Book

251

See also: Human activity and biodiversity 92–95 ■ The Verhulst equation

164–165 ■ Depletion of natural resources 262–265 ■ Urban sprawl 282–283

THE HUMAN FACTOR

healthcare and nutrition, cleaner

water, and more rights for workers.

By 1924, there were 2 billion people

in the world, and by 1960 there

were 3 billion, with most growth

occurring in the developing

countries of Latin America, Africa,

and South and East Asia.

A slowing birthrate

In Europe and North America in

the 20th century, wider access to

birth control, better education, and

more women entering the labor

market resulted in lower birth rates.

This phenomenon is now being

replicated for women everywhere.

Although the world’s population

passed 4 billion in 1974, 5 billion in

1987, 6 billion in 2000, and 7 billion

in 2011, the annual rate of increase

peaked near the end of the 1960s at

2.5 percent a year. Populations are

still growing quickly in some parts

of the developing world, but the

trend is not as rapid as it once was.

It took just 11 years for the world’s

population to rise from 6 billion

to 7 billion, but the increase to

8 billion is forecast to be 13 years,

then another 25 years to reach

9 billion. The UN forecasts a peak

of 11.2 billion in 2100.

Despite the slowing growth,

challenges remain. In 2009, a UN

report warned that the world would

need to produce 70 percent more

food by 2050 to feed its extra

population, thereby putting more

pressure on land, water, and energy

resources. Future population

growth is also likely to aggravate

many environmental problems,

such as pollution, and rising levels

of atmospheric greenhouse gases,

fueling global climate change. ■

China’s one-child

family planning policy

Until the 1960s, China

encouraged families to have

as many children as possible,

and the population rose

from 540 million in 1949 to

940 million in 1976. However,

the government soon became

concerned about the demand

on resources. In 1978, scientist

and politician Song Jian

calculated that China’s ideal

population was between 650

and 700 million people, and in

1979, his projections led the

government to create a new

policy limiting couples to one

child per family.

This one-child policy was

enforced more strictly in urban

areas than in the countryside;

in some regions a second child

was permitted if the first was

a girl. In the cities, however,

women were forced to abort

second children, and in 1983

alone, 21 million women were

forced to undergo sterilization.

The policy was relaxed in 2015,

but the government still only

allows two children per family.

A 1994 poster of a smiling mother

and daughter promotes China’s

one-child policy. Many baby girls

were abandoned or killed so that

their parents could try for a son.

This graph plots a comparison

between the annual growth rate

of the world population and the total

population in absolute numbers.

The data for the years after 2017

is a projection.

World population growth, 1750–2100

Annual growth rate as a percentage

of the world population

World population in numbers

1780

0.9 Billion

1.65 Billion

3 Billion

4.5 Billion

2.1%

0.1%

7.6 Billion

9.8 Billion

11.2 Billion

1760 1800182018401860188019001920194019601980200020202040206020802100

0%

0.2%

0.4%

0.6%

0.8%

1%

1.2%

1.4%

1.6%

1.8%

2%

8.6 Billion

2 Billion

US_250-251_Overpopulation.indd 251 22/11/2018 17:51