Answer:
a) The demographic transition refers to a pattern of changes in population growth rates that occur as societies undergo economic and social development. The transition typically involves four stages, each with distinct demographic characteristics. Here is a brief explanation of each stage along with some relevant indicators:
Pre-transition stage: In this stage, both the birth and death rates are high, resulting in a slow population growth rate. The population remains relatively stable over time. The graph below illustrates this stage, with a low population growth rate (blue line) and high birth and death rates (red and green lines, respectively).
Demographic Transition Stages Graph
Early transition stage: In this stage, the death rate begins to decline due to improvements in healthcare, sanitation, and nutrition. However, the birth rate remains high, leading to a rapid increase in population growth rate. This stage is characterized by a steep rise in population (blue line) and a decline in the death rate (green line), while the birth rate remains high (red line).
Late transition stage: In this stage, the birth rate begins to decline due to factors such as increased education, urbanization, and access to family planning. The population growth rate begins to slow down, but the population continues to increase due to the large number of young people in the population who are still entering their reproductive years. This stage is characterized by a declining birth rate (red line) and a declining population growth rate (blue line), while the death rate remains low (green line).
Post-transition stage: In this stage, both the birth and death rates are low, resulting in a low population growth rate. The population becomes stable or may even begin to decline. This stage is characterized by a low birth rate (red line) and a low population growth rate (blue line), while the death rate remains low (green line).
b) The unchecked growth of the population can have several environmental consequences, such as:
Resource depletion: As the population grows, there is an increasing demand for resources such as water, food, and energy. This can lead to the overexploitation and depletion of natural resources, leading to ecological imbalances and environmental degradation.
Habitat destruction: The expansion of human settlements and infrastructure to accommodate the growing population can lead to the destruction of natural habitats and biodiversity loss. This can result in the extinction of plant and animal species and the disruption of ecosystems.
Pollution: The increasing population can lead to the generation of more waste and pollution, including air pollution, water pollution, and soil contamination. This can have detrimental effects on human health and the environment, such as respiratory diseases, water-borne illnesses, and soil degradation.
Climate change: The increasing population can also contribute to climate change through the emission of greenhouse gases, deforestation, and land-use change. Climate change can have severe consequences such as rising sea levels, extreme weather events, and food insecurity.
Step-by-step explanation: