RAS Mains Topic 77: Major Environmental Issues

Study Material

Paper Paper II

Unit 3

1. Climate change: Global average temperature has risen 1.1°C above pre-industrial levels (2024 data, WMO). CO₂ concentration reached 425 ppm in 2024 vs 280 ppm pre-industrial. 2023 was the warmest year in recorded history (1.45°C above average). The Paris Agreement (2015) set targets of limiting warming to 1.5°C (aspirational) and 2°C (maximum) above pre-industrial levels.
2. Ozone layer depletion — PYQ 2023 (10 marks): The ozone layer (stratosphere, 15–35 km altitude) absorbs 97–99% of the Sun's harmful UV-B and UV-C radiation. Ozone-depleting substances (ODS): CFCs (chlorofluorocarbons), HCFCs, halons, carbon tetrachloride — mainly from refrigerants, aerosols, fire extinguishers. The Antarctic Ozone Hole was discovered in 1985 (British Antarctic Survey). The Montreal Protocol (1987) — called the most successful international environmental agreement — has reduced ODS by 99%.
3. Biodiversity loss: Earth is experiencing its 6th mass extinction — current extinction rate is 100–1,000× the natural background rate. The IUCN Red List (2024) has assessed 157,190 species; 44,016 are threatened (28%). Three major causes: habitat destruction (most significant — 80% of threatened species impacted), overexploitation (hunting, fishing), invasive species.
4. Desertification is the degradation of drylands due to human overuse and climate change. Affects 40% of Earth's land (dryland areas). Around 3.2 billion people are affected. Annual cost: ~$490 billion in lost productivity. UNCCD (UN Convention to Combat Desertification, 1994) is the global framework. Rajasthan relevance: Western Rajasthan faces severe desertification — dunes advancing 0.5–1.5 km/year before check dams and agroforestry.
5. Plastic pollution: Over 400 million tonnes of plastic produced annually (2023). Only 9% of all plastic ever produced has been recycled; 22% mismanaged. Microplastics (< 5 mm) found in deepest ocean (Mariana Trench), Arctic snow, human blood, and placenta. The Global Plastics Treaty (2024) — UN member states negotiating a binding treaty to end plastic pollution. India's single-use plastic ban (2022).
6. Deforestation: The world loses approximately 4.7 million hectares of forest annually (net, after reforestation). The Amazon Rainforest (Brazil) has lost 18–20% of its original cover since 1970 — concern about reaching a tipping point (~25%) beyond which the forest collapses into savanna (dieback). REDD+ (Reducing Emissions from Deforestation and Forest Degradation) is the UN mechanism for forest conservation.
7. Ocean acidification: Oceans absorb ~30% of all CO₂ emissions. This forms carbonic acid (H₂CO₃) → ocean pH has dropped from 8.2 to 8.1 (0.1 unit = 26% more acidic since pre-industrial times, due to logarithmic scale). Dissolves coral skeletons (CaCO₃) → coral bleaching and reef death. Threatens 25% of all marine species that depend on coral reefs.
8. Sea level rise: Global mean sea level has risen ~20 cm since 1900; rising at 3.7 mm/year in the 2010s. Two causes: thermal expansion (60–70%) of ocean water as it warms; ice melt from glaciers, Greenland, and Antarctica (30–40%). Pacific Island nations (Tuvalu, Kiribati, Maldives) face existential threat. India: Mumbai, Kolkata, Chennai, Kochi vulnerable.
9. Glacial retreat: Global glaciers losing ~31 billion tonnes of ice annually (2000–2019 data). Himalayan glaciers (India's "Water Tower") are retreating at accelerating rates; key example: Gangotri Glacier retreating ~22 m/year. UN 2025: International Year of Glaciers' Preservation.
10. Transboundary air pollution: PM2.5 (fine particulate matter <2.5 µm) is the most lethal air pollutant — causes cardiovascular and respiratory disease; ~7 million deaths/year globally (WHO). India's National Clean Air Programme (NCAP) targets 40% reduction in PM2.5/PM10 by 2026 (vs 2017 baseline). Delhi's AQI regularly breaches 400+ in winter (hazardous threshold: 300+).
11. Key international environmental agreements: Stockholm Conference (1972), Montreal Protocol (1987), Kyoto Protocol (1997), Paris Agreement (2015), CBD (1992), Kunming-Montreal Agreement (2022).
12. India's environmental commitments: NDC under Paris Agreement targets: Net Zero by 2070; 50% power from non-fossil fuels by 2030; 45% reduction in emissions intensity by 2030 (vs 2005). National Action Plan on Climate Change (NAPCC, 2008) — 8 missions including National Solar Mission, National Water Mission, Green India Mission.

Key facts

Climate change: Global average temperature has risen 1.1°C above pre-industrial levels (2024 data, WMO).
Ozone layer depletion — PYQ 2023 (10 marks): The ozone layer (stratosphere, 15–35 km altitude) absorbs 97–99% of the Sun's harmful UV-B and UV-C radia…
Biodiversity loss: Earth is experiencing its 6th mass extinction
Desertification is the degradation of drylands due to human overuse and climate change. Affects 40% of Earth's land (dryland areas).
Plastic pollution: Over 400 million tonnes of plastic produced annually (2023). Only 9% of all plastic ever produced has been recycled;

Key Points at a Glance

1
Climate change: Global average temperature has risen 1.1°C above pre-industrial levels (2024 data, WMO). CO₂ concentration reached 425 ppm in 2024 vs 280 ppm pre-industrial. 2023 was the warmest year in recorded history (1.45°C above average). The Paris Agreement (2015) set targets of limiting warming to 1.5°C (aspirational) and 2°C (maximum) above pre-industrial levels.
2
Ozone layer depletion — PYQ 2023 (10 marks): The ozone layer (stratosphere, 15–35 km altitude) absorbs 97–99% of the Sun's harmful UV-B and UV-C radiation. Ozone-depleting substances (ODS): CFCs (chlorofluorocarbons), HCFCs, halons, carbon tetrachloride — mainly from refrigerants, aerosols, fire extinguishers. The Antarctic Ozone Hole was discovered in 1985 (British Antarctic Survey). The Montreal Protocol (1987) — called the most successful international environmental agreement — has reduced ODS by 99%.
3
Biodiversity loss: Earth is experiencing its 6th mass extinction — current extinction rate is 100–1,000× the natural background rate. The IUCN Red List (2024) has assessed 157,190 species; 44,016 are threatened (28%). Three major causes: habitat destruction (most significant — 80% of threatened species impacted), overexploitation (hunting, fishing), invasive species.
4
Desertification is the degradation of drylands due to human overuse and climate change. Affects 40% of Earth's land (dryland areas). Around 3.2 billion people are affected. Annual cost: ~$490 billion in lost productivity. UNCCD (UN Convention to Combat Desertification, 1994) is the global framework. Rajasthan relevance: Western Rajasthan faces severe desertification — dunes advancing 0.5–1.5 km/year before check dams and agroforestry.
5
Plastic pollution: Over 400 million tonnes of plastic produced annually (2023). Only 9% of all plastic ever produced has been recycled; 22% mismanaged. Microplastics (< 5 mm) found in deepest ocean (Mariana Trench), Arctic snow, human blood, and placenta. The Global Plastics Treaty (2024) — UN member states negotiating a binding treaty to end plastic pollution. India's single-use plastic ban (2022).
6
Deforestation: The world loses approximately 4.7 million hectares of forest annually (net, after reforestation). The Amazon Rainforest (Brazil) has lost 18–20% of its original cover since 1970 — concern about reaching a tipping point (~25%) beyond which the forest collapses into savanna (dieback). REDD+ (Reducing Emissions from Deforestation and Forest Degradation) is the UN mechanism for forest conservation.
7
Ocean acidification: Oceans absorb ~30% of all CO₂ emissions. This forms carbonic acid (H₂CO₃) → ocean pH has dropped from 8.2 to 8.1 (0.1 unit = 26% more acidic since pre-industrial times, due to logarithmic scale). Dissolves coral skeletons (CaCO₃) → coral bleaching and reef death. Threatens 25% of all marine species that depend on coral reefs.
8
Sea level rise: Global mean sea level has risen ~20 cm since 1900; rising at 3.7 mm/year in the 2010s. Two causes: thermal expansion (60–70%) of ocean water as it warms; ice melt from glaciers, Greenland, and Antarctica (30–40%). Pacific Island nations (Tuvalu, Kiribati, Maldives) face existential threat. India: Mumbai, Kolkata, Chennai, Kochi vulnerable.
9
Glacial retreat: Global glaciers losing ~31 billion tonnes of ice annually (2000–2019 data). Himalayan glaciers (India's "Water Tower") are retreating at accelerating rates; key example: Gangotri Glacier retreating ~22 m/year. UN 2025: International Year of Glaciers' Preservation.
10
Transboundary air pollution: PM2.5 (fine particulate matter <2.5 µm) is the most lethal air pollutant — causes cardiovascular and respiratory disease; ~7 million deaths/year globally (WHO). India's National Clean Air Programme (NCAP) targets 40% reduction in PM2.5/PM10 by 2026 (vs 2017 baseline). Delhi's AQI regularly breaches 400+ in winter (hazardous threshold: 300+).
11
Key international environmental agreements: Stockholm Conference (1972), Montreal Protocol (1987), Kyoto Protocol (1997), Paris Agreement (2015), CBD (1992), Kunming-Montreal Agreement (2022).
12
India's environmental commitments: NDC under Paris Agreement targets: Net Zero by 2070; 50% power from non-fossil fuels by 2030; 45% reduction in emissions intensity by 2030 (vs 2005). National Action Plan on Climate Change (NAPCC, 2008) — 8 missions including National Solar Mission, National Water Mission, Green India Mission.

Introduction and Syllabus Scope

This topic is a high-return Paper II Geography area because RPSC repeatedly converts environmental issues into 5-mark and 10-mark questions, especially when a global issue has an India or Rajasthan angle. The RPSC syllabus names the environment in 2 separate Geography entries: Environmental and Ecological Issues under World Geography and Environmental Problems and Ecological Issues under Geography of India, making the environment a directly named syllabus area rather than a current-affairs add-on.

Topic 77 is the single highest-scoring topic in Paper II Geography, with a 6-year total of 35 marks and average 7.0 marks/year. It appeared in 4 of 5 exam years (2013, 2016, 2021, 2023) and both 2021 and 2023 had 10-mark questions from this topic. For 2026, this is a near-certainty for at least one 10-mark question.

PYQ pattern analysis:

2023: Q37 (10 marks) — "Ozone layer depletion causes and effects" — very specific
2021: Q11 (10 marks) — "Geopolitics of South East Asian countries" — broader environmental geopolitics
2016: 10 marks — environmental issues (ecological integrity)
2013: Q40 (20 marks) — ecological crisis India/world

2026 prediction: Given the trajectory, expect either (a) climate change/Paris Agreement (10 marks) or (b) biodiversity/ecosystem services (10 marks), plus possibly ozone depletion or plastic pollution (5 marks). RPSC tends to rotate — since ozone was asked in 2023, expect climate change or biodiversity in 2026.

Scope: World scope but with India-specific context relevant (India's NDCs, NAPCC, Himalayan glaciers). Rajasthan context is also relevant (desertification, water stress). Write answers with a global-to-India-to-Rajasthan structure where the question allows it; this keeps the answer aligned with the syllabus while showing administrative relevance.

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PREDICTED Predicted RAS Questions

Based on PYQ trends and 2026 syllabus analysis

1 5M What is the ozone layer? State the causes of its depletion. 5 marks · 50 words

Model Answer

The ozone layer in the stratosphere (15–35 km) absorbs 97–99% of harmful UV-B/UV-C radiation. Depletion is caused by Ozone-Depleting Substances (ODS): (1) CFCs (from refrigerants, aerosols) — one Cl atom destroys 100,000 O₃ molecules through catalytic reactions; (2) Halons (fire extinguishers); (3) Carbon tetrachloride; (4) Nitrous oxide (fertilisers — currently the most significant uncontrolled ODS). The Antarctic Polar Vortex amplifies depletion in spring.

~50 words • 5 marks