Unit 1: Introduction and sustainable development

CHE110 — Environmental Studies 10 min read

I. Orientation: the environment as an integrated system

Environmental studies treats the Earth as a single, finite, self-regulating system in which physical, chemical and biological processes are coupled to human activity. The modern discipline dates from the UN Conference on the Human Environment (Stockholm, 5–16 June 1972), which produced the Stockholm Declaration and led to the creation of UNEP; in India it was made compulsory at all levels of higher education following a Supreme Court directive and UGC core module (1991 onwards).

Governing assumptions that later sections depend on:

Finiteness: Earth is materially closed (only energy — ~1361 W/m² solar constant — crosses the boundary freely), so material resources circulate rather than accumulate.
Interconnection: every component is linked to every other; a change in one sphere propagates to the rest (e.g. fossil-fuel combustion → atmospheric CO₂ → ocean acidification → biosphere).
Thermodynamic limits: energy conversions are irreversible and degrade quality (2nd law), so no process is 100% efficient and waste is unavoidable.
Mass balance: inputs = outputs + accumulation; "away" does not exist — pollutants are relocated, transformed or stored.
Anthropogenic dominance: human impact is quantified by the IPAT identity.

TEXT

I = P × A × T
I = environmental impact   P = population (persons)
A = affluence (GDP or consumption per person)
T = technology (impact per unit of consumption)

Carrying limits: every population, including humans, is bounded by resource supply and waste-absorption capacity.

II. The environment: definition, constituents and structure

The word derives from the French environner, "to surround". Section 2(a) of India's Environment (Protection) Act, 1986 defines environment as including "water, air and land and the inter-relationship which exists among and between water, air and land, and human beings, other living creatures, plants, micro-organism and property."

A. Introduction to environment

The environment is the totality of external conditions — physical, chemical and biological — that act upon an organism or community and determine its form, survival and behaviour.

Classification by origin:
- Natural environment: unmodified physical and biological surroundings — forests, oceans, climate systems.
- Anthropogenic/built environment: cities, farmland, dams, roads; ~55% of humanity now lives in urban settings.
Classification by nature:
- Abiotic (physical): temperature, light, pH, salinity, soil texture, wind velocity.
- Biotic: producers, consumers, decomposers and their interactions (predation, competition, symbiosis).
Environment vs ecosystem: the ecosystem is the functional unit (biotic community + abiotic habitat + energy flow + nutrient cycling); the environment is the surrounding medium in which ecosystems operate.
Fundamental processes: unidirectional energy flow (only ~10% transfer between trophic levels — Lindeman's law) and cyclic biogeochemical cycling (carbon, nitrogen, phosphorus, water).

B. Components of environment

The environment is conventionally resolved into four interacting components, three abiotic and one biotic.

Atmosphere: the gaseous envelope; regulates temperature, filters UV-B via the ozone layer (peak ~20–25 km), supplies CO₂ for photosynthesis and O₂ for respiration.
Hydrosphere: all water — oceans, rivers, lakes, groundwater, ice; the solvent and transport medium of nutrients.
Lithosphere: soil and rock; the source of minerals, fossil fuels and the anchorage/nutrient store for plants.
Biosphere: all living organisms and the zone they occupy; the only component that actively transforms the other three (e.g. oxygenation of the atmosphere by cyanobacteria, ~2.4 billion years ago).
Social/cultural component: in human ecology a fifth component — institutions, economy, technology and culture — is added, since resource use is mediated by them.

C. Spheres of earth

The four spheres are structurally distinct but overlap in the thin surface layer where life exists.

Atmosphere (composition by volume, dry air): N₂ 78.08%, O₂ 20.95%, Ar 0.93%, CO₂ ~0.04% (≈420 ppm), plus variable water vapour (0–4%).
- Layers: troposphere (0–~12 km, lapse rate ≈ 6.5 °C/km, holds ~75% of atmospheric mass and all weather), stratosphere (~12–50 km, ozone layer, temperature rises), mesosphere (~50–85 km, coldest, meteors burn), thermosphere (>85 km, aurorae, ionosphere).
Hydrosphere: ~1.386 × 10⁹ km³ total; ~97.5% saline seawater, ~2.5% freshwater, of which roughly 68–69% is locked in glaciers and ice caps and ~30% is groundwater — less than 1% of freshwater is readily accessible surface water.
Lithosphere: rigid outer shell = crust + uppermost mantle, ~100 km thick; oceanic crust ~5–10 km (basaltic), continental crust ~30–70 km (granitic). Fertile topsoil forms at roughly 1 cm per 200–400 years, making soil effectively non-renewable.
Biosphere: the life zone, extending from ocean trenches (~11 km depth) to ~10 km altitude, but with almost all biomass in a band a few hundred metres thick; terrestrial net primary productivity ≈ 55–60 Gt C/yr.

D. Significance of the sphere interactions

Overlap zones drive the cycles: the water cycle couples hydrosphere–atmosphere–lithosphere; weathering of silicate rock couples lithosphere–atmosphere and regulates CO₂ over geological time.
Feedbacks: ice–albedo feedback (positive: melting ice lowers reflectivity, raises absorption, melts more ice); carbon uptake by oceans (negative, but causes acidification — surface ocean pH has fallen from ~8.2 to ~8.1 since pre-industrial times).

III. Environmental studies as a field of enquiry

Environmental studies is the systematic, problem-oriented study of environmental systems and of human interaction with them — descriptive in its science, normative in its policy dimension.

A. Multidisciplinary nature

No single discipline can describe a problem whose causes are physical, biological, economic and political at once.

Natural sciences: physics (radiation balance, pollutant dispersion), chemistry (photochemical smog, BOD/COD measurement), biology and ecology (biodiversity, food webs), geology and soil science, meteorology.
Applied/technical: environmental engineering (effluent treatment plants), remote sensing and GIS (land-use change mapping), biotechnology (bioremediation), statistics (dose–response modelling).
Social sciences: economics (externalities, cost–benefit, carbon pricing), law (Environment Protection Act 1986; Water Act 1974; Article 48A and 51A(g) of the Constitution), sociology and anthropology (Chipko movement, 1973), ethics, management.
Worked illustration — a single case, many lenses: the Bhopal gas leak (2–3 December 1984, methyl isocyanate) requires chemistry (MIC hydrolysis), medicine (epidemiology), engineering (safety design), law (liability), and sociology (settlement patterns near the plant) for a complete account.

B. Scope and importance of environmental studies

Scope — domains of study: natural resource conservation; ecology and ecosystems; biodiversity; pollution control; disaster management; environmental law and policy; environmental impact assessment (EIA Notification, 2006); climate change; human population and health.
Career and applied scope: research, green technology, pollution-control boards, NGOs, environmental journalism, industrial EHS compliance, ecotourism.
Importance:
- Problem scale: WHO attributes about 7 million premature deaths a year to air pollution; species are being lost at rates estimated at 100–1000 times the background rate.
- Informed citizenship: enables participation in public hearings, EIA processes and consumer choices.
- Legal and constitutional mandate: the right to a wholesome environment is read into Article 21 (right to life).
- Resource security: underpins water, food and energy planning.

IV. Sustainability, carrying capacity and the pillars

A. Concept of sustainability

Sustainability is the capacity of a system to maintain its functions and resource base indefinitely.

Operating rules (Herman Daly): renewable resources must not be harvested faster than they regenerate; non-renewables must be depleted no faster than renewable substitutes are developed; waste emissions must not exceed the assimilative capacity of the environment.
Ecological footprint: land/water area (global hectares, gha) needed to supply consumption and absorb wastes. World average demand ≈ 2.7 gha per person against a biocapacity of ~1.6 gha — an overshoot of roughly 70%, i.e. "1.7 Earths".
Strong vs weak sustainability:
1. Weak: natural capital and manufactured capital are substitutable; only total capital must be non-declining.
2. Strong: critical natural capital (ozone layer, climate stability, topsoil) has no substitute and must be maintained in physical terms.

B. Sustainable development

Defined in Our Common Future (Brundtland Commission report, 1987) as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs".

Two key ideas in the definition: the concept of needs, especially of the world's poor (priority), and the idea of limitations imposed by technology and social organisation on the environment's ability to meet needs.
Equity dimensions: intra-generational (between rich and poor today) and inter-generational (between present and future people).
Milestones: Stockholm 1972 → Brundtland 1987 → Rio Earth Summit 1992 (Agenda 21, Rio Declaration's 27 principles, UNFCCC, CBD) → Johannesburg 2002 → Rio+20 2012 ("The Future We Want") → Agenda 2030 in 2015.
Guiding principles: the precautionary principle, the polluter-pays principle and inter-generational equity — all held to be part of Indian environmental law (Vellore Citizens' Welfare Forum v. Union of India, 1996).

C. Carrying capacity

Carrying capacity (K) is the maximum population of a species that a given environment can support indefinitely without degradation of the resource base.