how does climate influence the distribution of population
Answers
Of all the geographic influences on population distribution, climatic conditions are perhaps the most important. Climate affects population distribution both directly as well as indirectly through its effects on soil, vegetation and agriculture that have direct bearings on the pattern of population distribution.
Physical Factors:
Physical factors that affect population distribution include altitude and latitude, relief, climate, soils, vegetation, water and location of mineral and energy resources. It is important to note that most of the physical factors influence population distribution only indirectly through climatic conditions.
The influences of latitude and altitude on population distribution cannot be separated from one another. High altitude in general imposes an ultimate physiological limit upon human existence due to reduced atmospheric pressure and low oxygen content. Therefore, very few permanent settlements can be seen in the lofty mountains of the world at a height above 5,000 metres. Staszewski, in his exhaustive analysis of the vertical distribution of population, has shown that both numbers and densities in different parts of the world decline with increasing altitude.
According to him, a little more than 56 per cent of the world’s population lives within 200 metres from the sea level, and over 80 per cent within 500 metres. However, in low latitude areas, which are otherwise hot and less favourable, high altitude provides suitable conditions for human habitation. Mountains in Africa and Latin America are much healthier than plains, and large cities have sprung up at high altitude. La Paz, the highest city in the world (3,640 m) and the capital of Bolivia, owes its existence to this factor. As against this, in the high latitude areas, it becomes extremely difficult to live beyond a few hundred metres from sea level. It is in this context that a famous population geographer has referred to “mountains that attract and mountains that repel”.
Abrupt changes in the density of population can be seen on the world map of population distribution where plains meet mountain ranges. Rising Himalayas, thus, mark the northern limit of dense population in the Ganga plain. Similarly, the Deccan plateaus with rugged and undulating topography appear distinct from the plains in respect of population concentration. In the mountainous areas valleys provide suitable locations for human settlements. Likewise, sun-facing slopes provide favourable locations for the emergence and growth of settlements.
This is particularly true in the temperate and other high latitude areas where insolation is very important. The river valleys may promote or restrict human settlements depending upon other geographic conditions. In Egypt, nearly 98 per cent of the population is concentrated forming a ribbon along the Nile River. As against this, in tropical swamps and dissected plateaus, river valleys tend to repel population.
Of all the geographic influences on population distribution, climatic conditions are perhaps the most important. Climate affects population distribution both directly as well as indirectly through its effects on soil, vegetation and agriculture that have direct bearings on the pattern of population distribution. Moreover, other physical factors like latitude and altitude also operate on population distribution through climatic conditions.
Although climatic optima are difficult to define, extremes of temperature, rainfall and humidity certainly limit the concentration of population in any part of the earth. In the Northern Hemisphere, extreme cold conditions in the high latitude areas have prevented human habitation. Likewise, extremely high temperature and aridity in the hot deserts of the world restrict human habitability. Some of the geographers in past have, therefore, gone to the extent of claiming a deterministic relationship between climate and population distribution.
It should, however, be noted that man has ability to adapt himself to different climatic conditions. This explains a high density in the tropics, which are otherwise marked with extremes of climatic conditions. Progress in science and technology has greatly augmented man’s ability to adapt to different climatic conditions. Though limited in magnitude, the peopling of the Alaska and Siberia during the last century owes to the scientific and technological advancements.
The cases of Java and the Amazon basin also serve to refute deterministic stance of relationship between climate and population distribution. Though, both of them experience equatorial type of climate, they differ markedly from one another in terms of population density. While Java is one of the most densely parts of the world, the Amazon basin is marked with a very sparse population.
Similarly, the quality of soils exerts an undeniable influence on the distribution of world population. The fertile alluvial and deltaic soils can support dense populations. Thus, most of the major concentrations of populations in the world are located in the river valleys and deltas. Great civilizations of the world have almost invariably flourished on good fertile alluvial soils. Similarly, the chernozems of steppe grasslands and rich volcanic soils can support dense population.