Lecture 16 Pop And Planetary Boundaries

Population & Planetary Boundaries

  • Overview
    This course module explores various facets of population dynamics, environmental justice, waste management, urban ecology, water pollution, and soil remediation.

  • Key Themes

    • Population and Planetary Boundaries (Michael Mascarenhas)

    • Environmental Justice (Michael Mascarenhas)

    • Waste Management (Kate O’Neill)

    • Urban Ecology (Chris Schell)

    • Water Pollution & Monitoring

    • Water & Agriculture (Kristen Dobbin)

    • Soil Pollution & Remediation (Celine Pallud)

    • Activity: Water, Pollution & Justice

Lecture 16: Population and Planetary Boundaries

World Population, Projections, and Demographic Factors

  1. Current Global Population

    • As of November 2022, the estimated world population is approximately 8 billion.

    • Historical growth includes significant events:

      • 10,000 BC: Population ~ 5 million

      • Ancient Rome: Population at its peak ~ 200 million

      • Industrial Revolution: Massive population increase

      • Global Trade and Green Revolutions: Influences on population growth

    • Quiz: How many people are there on earth today? Options: A. 6 billion B. 8 billion C. 10 billion D. 14 billion

  2. Future Projections

    • World Population Projections for 2100 indicate variability with estimates ranging from 6 billion to 14 billion.

    • There is a critical analysis of expected global population size showing:

      • 80% and 95% prediction intervals that account for migration and other factors.

  3. Regional Breakdown from UN

    • South Asia, Central Asia, East Asia, Southeast Asia, and others are delineated for better understanding demographic trends.

Fertility Rates

  1. Total Fertility Rate Estimates (1950-2021)

    • Displays how fertility rates have fluctuated across regions with replacement fertility rate set at 2.1 children per woman.

    • Illustrates a global decline in birth rates with diverse regional impacts.

    • Graphical representation of live births per woman across the decades, emphasizing regions with high versus low fertility rates.

Demographic Transition

  1. Stages of Demographic Transition

    • 1. Pre-industrial societies with food supply constraints.

    • 2. Rising populations due to improvements in food supply and sanitation.

    • 3. Decline in birth rates due to access to contraception, women's status enhancement, and urbanization.

    • 4. Aging populations leading to low birth and death rates (possible under replacement levels).

    • Visual or illustrative data supporting the transition stages.

Predictions of Population Trends

  1. Importance of Predictions

    • Highlights the challenges in predicting population trends due to variables such as migration and fertility changes.

    • Graphical data showcasing population size estimates from 1950 to 2100 indicating growth in uncertainty over extended forecasting horizons.

Stable Equilibrium States

  1. Concept Description

    • Stable Equilibrium: A state where systems return after disturbances.

    • Resilience: Defined as the system's ability to return to a stable state after a perturbation.

    • Critically important for ecological systems, offering illustrations for better understanding (e.g., rubber band example).

  2. Cattle Grazing Example

    • Examines the state of the system under different grazing pressures.

    • Rationale behind resilience and stability in ecological frameworks.

Planetary Boundaries

  1. Overview

    • Planetary Boundaries concept, as discussed in Rockström et al. (2009), further elaborates on how humanity operates within Earth's systems.

    • Examines resilience thresholds that can result in non-linear changes in systems.

  2. Human Impact and Goals

    • The aim is to restore resource usage toward pre-industrial conditions to preserve Holocene climatic conditions.

    • Various boundaries outlined, including:

      • Freshwater change

      • Stratospheric ozone depletion

      • Ocean acidification

      • Climate change impacts, etc.

  3. Operational Framework

    • Planetary boundary thresholds that delineate safe operating space versus zones of increasing risk.

    • Biophysical thresholds that signify catastrophic changes, emphasizing the importance of maintaining values below these thresholds for sustainability.

  4. Continuing Implications

    • Stress on understanding the irreversible nature of surpassing certain thresholds, which are universally applicable regardless of societal values.

Conclusions and Reflections

  1. Perspectives on Earth

    • Historical anecdote from Apollo 8 in 1968, emphasizing the significance of Earth as a unique oasis in space, presented through quotes from astronauts illustrating the awe when first observing Earth from the moon.

  2. Visual Representation

    • Societal and environmental ramifications demonstrated through graphic depiction of population data and boundary frameworks with attention to real socio-environmental status projections.

  3. Ethical and Philosophical Considerations

    • Calls for reflection upon humanity’s role in the Earth’s systems and the urgent need for sustainable practices to ensure planetary health.