CSS Environmental Sciences Foundations of Environmental Science and Sustainable Development Syllabus

What is the demographic transition model?

A model describing the shift from high birth/death rates to low birth/death rates as a society develops, through four (or five) stages.

State the formula for population growth rate (natural increase).

Natural increase rate = (Crude Birth Rate − Crude Death Rate); often expressed per 1,000 people or as a percentage.

What is the doubling time formula for a growing population?

Doubling time ≈ 70 ÷ annual percentage growth rate (the 'Rule of 70').

What is the I = PAT equation?

Environmental Impact = Population × Affluence × Technology — relating human impact to these three factors.

Define the 'poverty–environment trap' (vicious cycle).

Poverty forces overexploitation of natural resources, which degrades the environment, which deepens poverty — a self-reinforcing downward spiral.

What is biodiversity, and what are its three main levels?

The variety of life on Earth at three levels: genetic diversity, species diversity, and ecosystem diversity.

What are the main direct drivers of biodiversity loss (the 'HIPPO' threats)?

Habitat loss, Invasive species, Pollution, Population (human), and Overharvesting/overexploitation.

What is the difference between in-situ and ex-situ conservation?

In-situ conserves species in their natural habitat (e.g., national parks, reserves); ex-situ conserves them outside it (e.g., zoos, botanical gardens, seed/gene banks).

What is a 'biodiversity hotspot' as defined by Norman Myers?

A region with at least 1,500 endemic vascular plant species that has lost ≥70% of its original natural vegetation.

What does the IUCN Red List categorize, and name its threatened categories?

It assesses extinction risk of species; threatened categories are Vulnerable, Endangered, and Critically Endangered (beyond these: Extinct in the Wild, Extinct).

What is a keystone species?

A species whose impact on its ecosystem is disproportionately large relative to its abundance; its removal causes major ecosystem change.

Define energy security.

The uninterrupted, reliable, and affordable availability of energy sources to meet a nation's needs, balancing supply, access, and environmental sustainability.

Differentiate renewable and non-renewable energy sources with examples.

Renewable replenish naturally (solar, wind, hydro, geothermal, biomass); non-renewable are finite (coal, oil, natural gas, nuclear/uranium).

What is the energy mix, and why does diversification improve security?

The combination of different energy sources a country uses; diversification reduces dependence on any single source or supplier, lowering supply risk.

What characterizes a sustainable city?

A city designed for low environmental impact via efficient resource use, green spaces, public/low-carbon transport, waste recycling, and social equity.

What is the 'urban heat island' effect?

Urban areas being significantly warmer than surrounding rural areas due to dense built surfaces, reduced vegetation, and waste heat.

What is 'carrying capacity' in ecology?

The maximum population size of a species that an environment can sustain indefinitely, given available resources — denoted 'K' in the logistic growth model.

What is the logistic growth equation and what does it model?

dN/dt = rN[(K−N)/K]; it models population growth that slows as it approaches carrying capacity K, producing an S-shaped curve.

Define ecological footprint.

A measure of human demand on nature — the biologically productive land and water area (in global hectares) required to supply resources and absorb wastes.

What is biocapacity, and what is an ecological deficit?

Biocapacity is the ecosystem's capacity to produce resources and absorb waste; an ecological deficit occurs when the footprint exceeds biocapacity.

What is Earth Overshoot Day?

The date each year when humanity's resource demand exceeds what Earth can regenerate in that year.

What are the four pillars of food security as defined by the FAO?

Availability, Access, Utilization, and Stability of food.

What was the Green Revolution and what were its key inputs?

The mid-20th-century surge in crop yields using high-yielding variety (HYV) seeds, chemical fertilizers, pesticides, irrigation, and mechanization.

What is sustainable agriculture?

Farming that meets food needs while protecting soil, water, and biodiversity — using practices like crop rotation, organic inputs, IPM, and conservation tillage.

What is ecological restoration?

The process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed, back toward its natural/historic condition.

Differentiate restoration, rehabilitation, and reclamation.

Restoration returns an ecosystem to its original state; rehabilitation repairs ecosystem functions without full recovery; reclamation makes degraded/disturbed land usable again.

What is ecological succession, and name its two types?

The gradual, orderly change in species composition of a community over time; primary succession (on barren substrate) and secondary succession (after disturbance, soil intact).

What are the four components/spheres of the Earth system?

The lithosphere (land/rock), hydrosphere (water), atmosphere (air), and biosphere (life).

What is an ecosystem, and what are its two basic components?

A community of living organisms interacting with their physical environment; components are biotic (producers, consumers, decomposers) and abiotic (light, water, soil, climate).

State the 10% law (Lindeman's law) of energy transfer in a food chain.

Only about 10% of the energy at one trophic level is transferred to the next; the remaining ~90% is lost mainly as heat (metabolism).