Comprehensive Study Notes on Human Population Dynamics

Human Population Dynamics (13.1 - 13.4)

Human Population: Past & Present (13.1)

Ecological Footprint
- Definition: The impact imposed on the environment by the demand for natural resources.
- Initial population growth for humans occurred slowly because it was restricted by density-dependent factors.
Brief History of Human Population Growth
- Over the past two centuries, the human population has experienced exponential growth.
- Humans have successfully avoided the effects of density-dependent limiting factors through four specific methods:
  1. Expanded Geographic Range: Humans moved into and adapted to diverse environments.
  2. Agriculture: Technological developments in farming increased the carrying capacity of various regions.
  3. Harnessing Energy: The utilization of fossil fuels provided the power needed for expansion and production.
  4. Advances in Public Health: Improvements in medical care and sanitation reduced mortality rates.
Improvements in Agriculture & Technology
- Industrial Revolution: A period of significant technological advancement occurring from the $1800s$ to the $1900s$ .
- Key Developments: Many machines were developed during this time.
- Societal Impacts:
  - Significant increase in the food supply.
  - Reduction in manual labor needs.
  - Increase in urbanization as people moved to find machine-operated work.
  - General increase in the chances for human survival.
Human Demographics
- Age Structure: The categorization of a population in a specific country or community by age groups. This categorization directly impacts the population growth rates.
- Population Pyramid: A graphic representation that illustrates the distribution of various ages among males and females within a population.
- Canada’s Indigenous Peoples:
  - Recognized as custodians of the land with very diverse cultures.
  - Transitioning towards urban living, though $46\%$ still live in rural areas.
  - Demonstrate a different population growth pattern compared to non-indigenous peoples.
- Population Growth and Economic Development:
  - Growth typically correlates with increased competition for resources, lower per capita income, and a lower overall standard of living.
  - Demographic Transition Model: A graph depicting changes in how people live to explain shifts in population sizes over time.
  - Economic Impacts: Larger families are more costly to maintain, which eventually leads to a drop in the population growth rate.
  - Public Health: Improvements in health services lead to a reduction in the death rate.
Planned Reproduction
- To reduce the population growth rate, a society must either reduce the birth rate or increase the death rate.
- Since increasing the death rate is considered immoral, the focus is on lowering the birth rate via birth control or waiting longer to reproduce.
- Replacement Rate: The specific rate at which individuals have children to "replace" themselves when they die.
- Values:
  - A value of $2.1$ is required to achieve Zero Population Growth ( $\text{ZPG}$ ).
  - Values greater than $2.1$ indicate a growing population.

Implications of Human Population Growth (13.2)

Urbanization
- Milestone: In $2007$ , for the first time, more humans lived in urban areas than in rural areas.
- Agricultural Shift: The shift from many small farms to a few large-scale farms has driven people to move into cities.
- Urban Characteristics: Cities offer diversity and proximity to employment.
- Urban Sprawl: Caused by the prevalence of cars and roadways.
- Environmental Consequences: Sprawl changes land use and alters natural waterways. The use of impermeable concrete prevents water from soaking into the ground, further changing water systems.
- Waste Management: Increasing population leads to issues with landfills.
- Emissions: Vehicle emissions pollute both water quality and air quality.
Feeding the World
- Global food production has increased significantly since the Industrial Revolution.
- Industrialized Agriculture: A method of growing food using machines and synthetic fertilizers or pesticides.
- Traditional Agriculture: A method of growing food by hand, utilizing natural fertilizers and pesticides.
- Malnutrition: A condition where the body lacks proper nutrients. In $2010$ , approximately $925$ million people were considered malnourished.
- Causes of World Hunger:
  - Natural Disasters: Floods and droughts.
  - Conflict: Wars.
  - Poverty: Having too few resources to grow or purchase food.
  - Poor Agricultural Infrastructure: Lack of systems to transport or store food.
  - Over-exploitation: Environmental degradation such as soil exhaustion.
Energy Use in the Food Web
- Energy Pyramid: A model depicting the flow of usable energy within a food web.
- Trophic Level: Represents one energy transfer level in a food chain or web.
- Trophic Efficiency: Generally estimated at $10\%$ .
- Considerations: One must account for the energy required to produce food and the ecological footprint of the agriculture. Consuming local foods conserves more energy by reducing transport requirements.
Threats to Soil
- Protection of the world's topsoil is vital.
- Major threats include:
  - Soil erosion.
  - Loss of soil fertility (nutrient depletion).
  - Desertification.
  - Salinization.
Sustainable Agriculture
- Also known as Low Input Agriculture.
- Uses less energy and fewer resources than industrialized methods while increasing soil fertility.
- Increases biodiversity by planting a larger variety of crops.
- Organic Agriculture: Growing food specifically without synthetic pesticides and fertilizers.
- This industry is currently expanding and helps reduce the ecological footprint, though much food is still imported.
Aquaculture
- A method to combat shrinking fish supplies by raising fish and shellfish as crops.
- Accounts for approximately half of the fish and shellfish consumed by humans.
- Considered a technically renewable resource.
Air Quality Concerns
- Human population growth contributes to pollution and greenhouse gas emissions.
- Linked to climate change and the disruption of the carbon cycle.
- Causes aggravation of respiratory illnesses.
Water Quality Concerns
- Water Composition: $97.4\%$ of the world's water is salt water.
- Freshwater: Only $2.6\%$ of the world's water is fresh, and most of that is trapped in ice or located in groundwater.
- Distribution: Freshwater is not equally distributed globally, despite the hydrologic cycle.
- Pollution: Water quality is threatened by agricultural runoff and industrial processes.

Human Population: The Future (13.4)

Supply and Demand
- The Earth has a finite carrying capacity because non-renewable resources are limited.
- Ecological Deficit: Occurs when resource use and waste production exceed sustainable levels.
- Biocapacity: A measure of an ecosystem's ability to produce useful biological materials and absorb waste created by humans.
- Measurement: Quantified in global hectares ( $\text{gha}$ ).
- Variables: Dependent on biologically productive areas of land (e.g., farming, forestry) and water. Tropical rainforests have a very high biocapacity.
- Distribution: Biocapacity is unevenly distributed across the globe.
Human Population Projections
- While the population was once projected to increase indefinitely, data from the Total Fertility Index suggest the population is not growing as quickly as previously thought.
- UN Millennium Development Goals (Target Year: 2015):
  1. Eliminate poverty and hunger.
  2. Achieve universal education and eliminate the wage gap.
  3. Improved health outcomes.
  4. Ensure environmental sustainability.
Conserving Biodiversity & Taking Action
- Biodiversity Defined: The variety in genetics, species, and ecosystems.
- Function: Biodiversity assists with nutrient cycling and the maintenance of resources.
- Impact of Climate Change: Changes in climate affect the geographic ranges of species, including the spread of diseases.
- Actions for Conservation:
  - Conserving water.
  - Utilizing alternate energy sources.
  - Implementing Reduce, Reuse, and Recycle protocols.
  - Making sustainable food choices.