Wk 10: Human populations and global environments

What are planetary boundaries? 

A framework defining a safe operating space for humanity based on Earth‑system processes; crossing boundaries increases risk of abrupt or irreversible change.

How many planetary boundaries are currently exceeded (2023–2025)? 

Six to seven of nine: biosphere integrity, climate change, novel entities, land‑system change, freshwater change, biogeochemical flows.

Why are planetary boundaries measured against the Holocene? 

Because the Holocene provided stable conditions under which human societies evolved.

Key scientific critique of planetary boundaries 

Uncertainty in defining thresholds and measuring transgression.

Key political critique of planetary boundaries 

They risk implying “within limits = safe,” and treat humanity as a single undifferentiated actor.

Global population milestone (2022) 

Human population surpassed 8 billion.

Is global population growth slowing? 

Yes — growth rate peaked mid‑20th century and is projected to decline through the 21st century.

Which regions will drive most future population growth? 

Africa and parts of Asia.

What is the Malthusian argument? 

Population grows exponentially while food supply grows linearly → inevitable scarcity.

What did the Ehrlichs argue in The Population Bomb? 

Overpopulation would cause global famine; advocated limiting population growth.

What did Barry Commoner argue in The Closing Circle? 

Environmental problems stem from capitalism and inequality, not population size.

What does the IPAT formula represent? 

Impact = Population × Affluence × Technology.

What is an ecological footprint? 

A measure of resource use expressed as the amount of land/water needed to sustain consumption and absorb waste.

What is Earth Overshoot Day? 

The date when humanity’s resource use exceeds Earth’s annual regenerative capacity.

What do Lorenz curves reveal about ecological footprints? 

High‑income groups consume disproportionately more energy and resources than low‑income groups.

What is a key limitation of ecological footprint metrics? 

They show how much impact occurs but not where impacts are felt or who is responsible.

What are shadow places? 

Disregarded places that bear ecological and social costs of consumption elsewhere; highlights unequal geographies of responsibility.

Why is plastic pollution not simply a “population problem”? 

Driven by systemic factors: petrochemical industries, packaging manufacturers, global trade, and unequal waste export patterns.

What is the “dark side” of population control debates? 

Historically linked to racism, coercion, eco‑fascism, and blaming the poor for environmental degradation.

What is the “safe and just operating space” (the doughnut model)? 

A framework balancing planetary boundaries (ecological ceiling) with social foundations (health, equity, education) to ensure human wellbeing without overshoot.