Pollution, Climate Change and Conservation

Types of pollution

• Air – CO, SO₂, NOₓ, PM2.5. SO₂ and NOₓ cause acid rain (damaging the Taj Mahal – 'marble cancer').
• Water – sewage and fertiliser run-off cause eutrophication (algal bloom, low oxygen).
• Soil and noise – noise is measured in decibels (dB).

Ozone and greenhouse effect

The ozone layer (stratosphere) absorbs UV rays; CFCs deplete it. The Montreal Protocol (1987) phases out ozone-depleting substances. Greenhouse gases – CO₂, CH₄, N₂O, water vapour – trap heat and cause global warming. The Paris Agreement (2015) aims to limit warming to well below 2 °C.

Conservation in India

• National parks, wildlife sanctuaries and biosphere reserves. Jim Corbett (1936) is India's first national park.
• Project Tiger (1973), Project Elephant (1992).
• Chipko Movement (1973) – tree hugging in Uttarakhand.

Exam tips

1. World Environment Day – 5 June; Ozone Day – 16 September.
2. Methane is emitted by paddy fields and cattle.

Analogy

The greenhouse effect is like sitting in a car parked in the sun with the windows closed. Sunlight gets in easily, but the heat can't escape, so the inside keeps warming. Greenhouse gases are the closed windows of the Earth — a little is good, too much makes it unbearable.