Chapter 2
CHAPTER NO.2 POPULATION AND ENVIRONMENT
As an evolutionary unit, population may be defined
as a group of similarly adapted, interbreeding organisms belonging to the same
species. However, with respect to environment, population is defined as
organisms or members of the same species living and interacting in a particular
geographi-cal area, Homo sapiens is the highly evolved species and in this
chapter we shall deal with human population only. Being the most intelligent,
man has the ability to change the environment for his own
well being. Due to an increase in human population,
various activities of man have raised many environmental issues and problems.
In this context, scientific studies of populations are necessary to understand
its impact on environment. These studies include population growth,
distribution, density,literacy, urbanization etc. These are likely to be useful
in understanding problems being faced by man in agriculture, economic planning,
wild life management etc.
Before considering all these aspects, it is essential
to know some common terms used in demography (Fig. 2.1). It is the study of
population in all aspects like number, sex ratio, age groups,
Population density : It refers to the number of
human beings living in a unit of space, normally expressed as per square
kilometer.
Birth rate : It deals with rate of addition of newly
born individuals in a population. It is also referred
to as natality rate. It is usually expressed as the
number of births per year per thousand persons in a
population. It is also referred to as natality rate.
Death rate: It refers to the rate of individuals
which are lost by way of deaths. It is expressed as the number of deaths per
year per thousand persons in a population. It is also called mortality rate.
Migration: It is the movement of people to new
places either within the same country (internal migration) or to another
country (extemal migration). When new people are added from outside, it is
called immigration and if they move out from a population, it is called emigration.
Age structure of population : It refers to
proportion of individuals of different age groups in a population.
Sex ratio : It is the number of female per thousand
of males.
POPULATION THEORIES
Man has been concerned with the population of his
own species since ancient times, but re-cently it has been felt that population
dynamics influences human welfare.
Once of he earliest theories of population dynamics
was proposed by Plato and Aristotle. It states that the optimum size of a
population is that in which man's potentialities can be carefully developed. It
is possible only when the population size is economically self sufficient and
is capable of defending itself.
At the close of the 18th century, Thomas Robert
Malthus (1798), a British economist and demographer published his theory of
population in the form of “An Essay on the Principle of Popu-
lation’. According to him, population always
increases geometrically (2, 4, 8, 16, 32......), whereas,food and means of
subsistence increase arithmetically (2, 4, 5, 8, 10......) and thus there will
always be an imbalance between population, food and space. Malthus concluded
that if the population
growth was not checked, the nature will play its
role through checks such as wars, famines, droughts,tsunamis, disease etc. to
the decline the population.
POPULATION GROWTH
The most important aspect of population that affects
the environment is population growth. As per record, the human population was
about 0.6 billion in 1700 A.D. At the beginning of 20th
century, it increased to 1.6 billions and by the end
of this century, human population reached 6.1 billions. It took 150 years to
double the population from 0.6 billion to 1.2 billions, but in the next 150
years, it increased five times. It is also believed that in the next 50 years,
the population will ctoss 9 billion mark, As per UN estimate, the current
annual growth rate of the world population is about 2.5%. The natality rate per
minute is 234. Another interesting aspect of population growth
is that it is not uniform everywhere throughout the
globe. In fact, the distribution pattern of popu-lation varies in different
regions. According to an estimate, about 20% world population lives in half of
the total area of earth that includes Europe, North America, former USSR and
Oceania.
The rest of world population lives in the remaining
half of the earth area. It includes all developing countries. The growth rate
is also highest in developing countries e.g. the highest growth in the world is
in Africa. In addition to the rising growth rate of developing countries
e.g.population
below 15 years is 45% in Africa and 22% in Europe.
However, the percentage of population above 65 years is more in developed
countries.
Due to obvious reasons, it is essential to know the
carrying capacity of the environment. It is defined as the maximum population
size that can be supported by the environment. For this purpose,environment has
two components:
Life supportive components: It is the environment
that provides food, energy, air and water.
Waste assimilative components: This part of the
environment includes the assimilation of waste material produced by human
activities.
As the carrying capacity of the earth is limited
and, therefore, the outcome of the rapid growth of population produces harmful
effect on the environment, The United Nations Environmet Programme
(UNEP) has worked ont that the higher population
growth will lead to poverty and an increased rate of environmental degradation.
Now, let us examine the impact of population growth
or some components of carrying capacity of the environment.
Umpact on food : Populaticn growth has a direct
relationship with food. The scarcity of food will lead to an overexploitation
of land and other resources resulting in tension and conflict amongst human
beings. Presently, 60% of the people in the world are underfed. In India about
70-80% children are suffering from malnutrition.
Impact on poverty : Population and poverty are
greatly related to cach other. Any increases in population puts a pressure on
basic necessities such as houses, jobs, medical facilties etc.
It will lead to poverty. As a result, more and more
people will become poor and poverty tidden.
Impact on raw materials : An increase in population
is directly related to an added pres-sure on industries to produce more and
more goods to fulfill the demands of the people.There are two main sources of
raw material i.e., the mines and the forests. Over mining
operations to extract more coal, iron ores and other
ores have led to the closure of many mines. Similarly, to get more timber,
rubber and herbs, the forests are being destroyed. The
loss of forests has a far reaching effect on the
environment resulting in Green House Effect,It will lead to global warming. Due
to rise is global temperature, the old glaciers has started melting and
subsequently the sea level will rise and many islands and coastal areas will
face a major threat of getting submerged under the water.
impact on energy : Most of the developed and
devloping countries of the world are head-ing towards heavy industrialization
to create more jobs for the growing population and to produce more products to
meet their demands, Industries cannot run without energy. The energy can be
obtained from fossil fuels like coal, petroleum, natural gas, etc. Due to their
over exploitation, they may start depleting very fast.
URBANISATION
Urbanisation means the number of people living in
the cities. It has become a characteristic trend in human civilization to shift
to cities. In the United States, only 6% population was living in cities in
1800, but at present more than 70% population lives in urban areas. In
Netherlands, around 90% population lives in cities. At the global level, about
29% population was living in cities in 1950,Tn 1990 this figure rose to 43%.
Due to expanding popuation, even the cities cross their administra-tive
boundaries, leading to a chaotic situation. For example, to decrease the
pressure of population
on Delhi, the satellite towns like Noida, Faridabad,
Ghaziabad and Gurgaon were developed but now they have almost became a part of
Delhi itself. The same is the case with other bigger metros
like Mumbai, Kolkata, Chennai etc. The principle
cause of this growth is urbanization vis-a-vis in-
livelihood. Another reason of their shifting to the
cities is the availability of better medical and educa-and thus they are also
migrating to cities.
This unimaginative influx of population to almost
all bigger cities has created scarcity of houses,drinking water, electricity,
etc. The urbanization has led to a very serious problem, i.c., the growth of
slum areas around the cities. The governments are always in a fix to solve the
problems of the slums.
LITERACY
Literacy is an ability to read and write, but for
the purpose of ecology, it is the educational level of the people of a country
and the world. In 2001, the literacy rate of India was 64.8%, but if it is
compared with Asia and Africa, it is only about 30% i.e. 70% people are
illiterate. Illiterate people are sometimes considered as a burden on a country
and a society as they cannot contribute in the
development in a bigger way.
With environment as a subject, one can early see the
difference between illiterates and literates.The literate societies tend to
live in relatively clean environment. Without awareness people fail to
differentiate between biodegradable and non-bicdegradable substances that is
why they do not shop
using plastic bags and other such products. The use
of plastic has created many environment prob-lems, especially relating to
sewage disposal and choking of water bodies.
Thus, to conclude, further population explosion
needs to be avoided otherwise it will deteriorate the environment, beyond
repair.
EXERCISE
(A) Very short answer type questions (1
mark each) :
1. Whatis demography?
2. Define birth rate.
3. Define death rate.
4. What is sex ratio?
5. What is responsible for population growth, emigration
or immigration?
6. Whatis poverty?
7. Define literacy.
(B) Short answer type questions (2
marks each) :
1, Explain carrying capacity.
2. How population explosion has affected the food
production?
3. Name four satellite towns?
4, What is the impact of population growth on
energy?
(C) Short answer type questions (4
marks each):
1. What is Malthus theary on population?
2. How does are urbanisation affect the environment?
(D) Long answer type questions: (5
marks each):
1. Discuss the impact of population growth on
various components of carrying capacity of the environment.
