Uneven distribution and density of global populations

Population distribution refers to the pattern of where people live across the globe, while population density measures the number of people per unit area, typically per square kilometre. These patterns are far from uniform due to varying environmental and social conditions.

Factors influencing population distribution

• Favourable conditions - Areas with supportive environments, such as coastal plains and river valleys, attract larger populations due to access to water and arable land.
• Unfavourable conditions - Harsh environments like deserts or glaciers are sparsely populated or uninhabited because they cannot sustain large numbers of people.

Variations in population density

• Global differences - Population density varies widely between countries. For instance, a densely populated country like Singapore has over 8,000 people per km², while a sparsely populated country like Mongolia has around 2 people per km².
• Regional concentrations - High-density areas are often found between 20°N and 60°N, with the highest densities in South and East Asia.
• Within-country variations - Even within a single country, density can differ significantly, with urban centres often having much higher densities than rural areas.

Rapid growth of global population since 1800

The global population has seen a dramatic increase over the past two centuries, driven by advancements in various fields that have altered birth and death rates.

Historical population trends

• Early milestones - The world's population reached 1 billion around 1804, after centuries of slow growth limited by famine, disease, and conflict.
• 19th-century growth - Significant increases occurred in developed regions like North America and Western Europe due to improvements in medicine and food production, which boosted life expectancy and reduced infant mortality. For example, the population of Germany and France increased from approximately 35 million in 1800 to 80 million by 1900.
• Developing regions - During the same period, populations in developing areas remained stable due to high infant and maternal mortality rates and frequent famines.

Modern population surge

• Post-1950 growth - Global population soared from approximately 2.5 billion in 1950 to 7.5 billion by 2017, with projections estimating 9 billion by 2050.
• Driving factors - Most of this growth has occurred in developing countries, where life expectancy has risen and death rates have fallen sharply.
• Population decline in some areas - Certain countries, such as Japan, are experiencing population decreases due to higher death rates than birth rates, though global numbers continue to rise.
• Urban shift - Population distribution has shifted towards urban areas, with cities growing faster than rural regions, leading to higher densities in urban centres.

Impact of the physical environment on population distribution

The physical environment plays a crucial role in determining where populations settle and how large they grow. Key environmental factors include climate, soil quality, and resource availability.

Effects of climate on population

• Climate preferences - Populations tend to concentrate in temperate and tropical climates, which support food production, as seen in regions like Western Europe. In contrast, arid areas like the Sahara Desert have very few inhabitants.
• Climate change impacts - Rising sea levels are forcing coastal and island populations to relocate inland. Additionally, climate change is reducing nutrition levels in some developing regions, affecting population health and distribution.

Role of soil fertility

• Agricultural support - Fertile soils are critical for food production and have historically influenced settlement locations. Many ancient cities, such as those near volcanic regions, were established due to rich soils.
• Floodplain benefits - Countries with extensive floodplains, like Vietnam, can support large populations through intensive agriculture.
• Soil erosion challenges - Degradation of soil through erosion can drive migration as farming becomes unsustainable in affected areas.

Importance of resource distribution

• Water availability - Access to fresh water is vital for population growth. Deserts, lacking sufficient water, support only small populations.
• Consequences of scarcity - Insufficient safe water can lead to food insecurity and health issues, sometimes causing population declines.
• Abundant resources - Regions with ample natural food and fuel, such as tropical rainforests, can sustain larger populations.
• Economic resources - The presence of energy and mineral resources, like oil or gold, often leads to local population concentrations as people move for work opportunities.

Influence of development processes on population change

Historical and ongoing development processes have significantly shaped population size, growth rates, and distribution patterns across the world.

Historical development milestones

• Neolithic Revolution:
  • Around 12,000 years ago, the shift from hunting and gathering to farming in regions like western Asia led to permanent settlements.
  • This reliable food supply caused population increases in these areas.
• Industrial Revolution:
  • Between approximately 1760 and 1850, the rise of machinery and factories in developed countries triggered rapid population growth.
  • Factors influencing this included lower death rates from better food production and improved diets, alongside urban migration as farming required less labour.

Modern development impacts

• Population growth patterns - As countries develop, population growth often rises initially due to better healthcare and food security, then slows as education and urbanisation reduce birth rates.
• Urban concentration - Development tends to concentrate populations in urban areas, where infrastructure and job opportunities are more abundant, further altering distribution patterns.