Environment and its functions
Environment means all the living (plants, animals, people) and non-living (air, water, soil, sunlight) things around us and how they act on each other.
Four functions
- Supplies resources: renewable (trees, fish) and non-renewable (coal, oil).
- Absorbs waste: air, water and soil break down and hold wastes.
- Sustains life: gives genetic and biodiversity, clean air and water.
- Gives beauty: scenery and nature we enjoy (aesthetic value).
Carrying capacity
The environment can do these jobs only if (1) we extract resources more slowly than they renew, and (2) wastes stay within its absorptive capacity. When either rule is broken, we face an environmental crisis.
What is sustainable development?
The UN Brundtland Commission (1987) defined sustainable development as development that meets the needs of the present generation without harming the ability of future generations to meet their own needs.
It asks us to keep the stock of natural resources so that our grandchildren have at least the same quality of life as we do.
Economist Herman Daly's rules (in simple words)
- Keep population at a level the environment can carry.
- Use technology that saves resources, not wastes them.
- Harvest renewable resources no faster than they regrow.
- Use non-renewable resources no faster than renewable substitutes are made.
- Fix the damage pollution causes.
Effects on resources and environment in India
India has rich soil, rivers, forests, minerals and sunshine. But fast population growth, industry and farming put huge pressure on them. Two big problems are air pollution in cities and water pollution from sewage and industrial waste.
- Land degradation: loss of forests, shifting cultivation, overgrazing, too much fertiliser and poor irrigation (waterlogging, salinity) weaken soil.
- Deforestation and biodiversity loss: forest area per person is very low; many species are threatened.
- Air pollution: vehicles, power plants, factories and crop-stubble burning.
- Water pollution and scarcity: untreated sewage and chemicals; over-pumping lowers groundwater.
- Solid waste: plastics and e-waste pile up.
The opportunity cost of this damage is high: money spent on health and on cleaning up could have been used for development.
Global warming and ozone depletion
Global warming is the slow rise in the average temperature of the earth's lower atmosphere. Burning coal, oil and gas and cutting forests add greenhouse gases (carbon dioxide, methane and others). These gases trap heat like a blanket.
Effects
- Melting glaciers and polar ice, rising sea levels, flooding of coasts.
- More extreme heat waves, floods and droughts.
- Changes in crop yields and spread of diseases.
Countries agreed on steps to cut emissions: the Kyoto Protocol (1997) and the Paris Agreement (2015).
Ozone depletion
The ozone layer high in the sky blocks harmful ultraviolet rays. Chemicals like CFCs (once used in fridges and ACs) thin it, causing the "ozone hole". The Montreal Protocol (1987) phased out CFCs.
Strategies for sustainable development
- Non-conventional energy: solar, wind, small (mini) hydel plants instead of coal.
- Cleaner fuels: LPG and gobar gas in villages instead of wood and dung cakes; CNG in city buses.
- Biocomposting: turning waste into compost with earthworms instead of chemical fertiliser.
- Biopest control: neem, birds and friendly insects instead of chemical pesticides.
- Traditional knowledge: Indian ways of farming, medicine (Ayurveda) and water harvesting that respect nature.
- Reduce, reuse and recycle; public transport; saving water.
Key formulas and definitions
- Sustainable development: meeting present needs without harming future generations' ability to meet theirs (Brundtland, 1987).
- Carrying capacity: extraction ≤ regeneration and waste ≤ absorptive capacity.
- Absorptive capacity: the environment's ability to absorb damage/waste.
- Global warming: rise in average earth temperature due to greenhouse gases.
- Environmental crisis: when demand on the environment exceeds its capacity.
Worked examples
1. A forest has 10,000 trees and regrows 500 a year. People cut 800 a year. After 5 years, how many trees?
Net loss = 800 − 500 = 300 a year. After 5 years: 10,000 − 1,500 = 8,500. Extraction exceeds regeneration, so it is not sustainable.
2. In the same forest, what is the maximum sustainable cutting per year?
500 trees a year (equal to regrowth). The stock then stays at 10,000.
3. A river can clean 200 tonnes of waste a day. A town dumps 260 tonnes. What happens?
Waste exceeds absorptive capacity by 60 tonnes a day, so pollution builds up. The town must treat at least 60 tonnes before dumping.
4. A family replaces 10 kg of wood a day with a gobar gas plant. How much wood is saved in a year?
10 × 365 = 3,650 kg a year, plus less smoke inside the house.
Common mistakes
- Thinking sustainable development means no development. It means development that lasts.
- Mixing up global warming and ozone depletion. Warming is trapped heat from greenhouse gases; ozone depletion lets in UV rays.
- Believing renewable resources can never run out. They do if used faster than they regrow.
- Forgetting the absorbing function. The environment also takes in our waste, and that has limits.