Prelims GS I: Environmental ecology, biodiversity and climate change · Unit 27 of 42
Climate Change, Pollution and Environmental Conventions
Greenhouse effect, global warming impacts, UNFCCC, Kyoto and Paris, India's NDCs and missions, ozone, air and water pollution, and key international conventions.
Syllabus lines this unit covers
- Climate change
- Environmental pollution and degradation
- International environmental conventions and India's commitments
Climate change basics
- The greenhouse effect is natural and keeps the earth at about 15 °C. Human activity has increased it.
- Main greenhouse gases:
- CO₂: fossil fuels and deforestation; about three-quarters of emissions;
- methane: rice paddies, livestock, landfills;
- nitrous oxide: fertilisers;
- HFCs, PFCs and SF₆.
- Global Warming Potential: methane is about 28 times as strong as CO₂ over 100 years.
- IPCC AR6 (2021–23):
- Warming is already about 1.1 °C above pre-industrial levels.
- It is "unequivocally" caused by humans.
- 2024 was the first calendar year above 1.5 °C (WMO).
- Impacts on India:
- heat waves;
- erratic monsoons, with more extreme rain;
- Himalayan glacier retreat and glacial lake outburst floods (e.g. Sikkim, 2023);
- sea-level rise in the Sundarbans and Mumbai;
- drought and floods in Bihar (floods in the north, drought in the south);
- lower crop yields.
Global climate regime
| Year | Event | Outcome |
|---|---|---|
| 1988 | IPCC set up (WMO + UNEP) | Assessment reports |
| 1992 | UNFCCC at Rio | Common but differentiated responsibilities (CBDR); Annex I countries |
| 1997 | Kyoto Protocol (COP3) | Binding cuts for developed countries; CDM, emissions trading |
| 2015 | Paris Agreement (COP21) | Well below 2 °C, pursue 1.5 °C; NDCs from all; 5-yearly global stocktake |
| 2021 | COP26 Glasgow | India's Panchamrit; "phase down" coal |
| 2022 | COP27 Sharm el-Sheikh | Loss and Damage Fund agreed |
| 2023 | COP28 Dubai | First global stocktake; "transition away from fossil fuels"; L&D fund operational |
| 2024 | COP29 Baku | New finance goal (NCQG): US$ 300 billion a year by 2035 |
| 2025 | COP30 Belém (Brazil) | Focus on forests and adaptation |
India's Panchamrit (COP26) and updated NDC (2022):
- Emissions intensity of GDP down 45% by 2030 from 2005 levels.
- 50% of installed power capacity from non-fossil sources by 2030. This was reached in 2025.
- 500 GW of non-fossil capacity by 2030.
- An additional carbon sink of 2.5–3 billion tonnes of CO₂ equivalent through forests.
- Net zero by 2070.
India also promotes Mission LiFE, the International Solar Alliance (2015, with France; headquarters in Gurugram), CDRI (the Coalition for Disaster Resilient Infrastructure) and the Global Biofuels Alliance (2023).
Domestic action:
- the NAPCC (2008) with 8 missions, and State Action Plans on Climate Change (Bihar and Jharkhand have them);
- the Carbon Credit Trading Scheme (2023);
- the Green Hydrogen Mission;
- E20 ethanol blending, reached in 2025;
- FAME and PM E-DRIVE for electric vehicles.
Ozone layer
- The ozone layer is in the stratosphere and is damaged by CFCs and halons. The ozone hole is over Antarctica.
- Vienna Convention (1985) and Montreal Protocol (1987): the most successful environmental treaty.
- Kigali Amendment (2016): phase-down of HFCs. India starts in 2028.
- World Ozone Day is 16 September.
Pollution
Air pollution
- Main pollutants: PM2.5 and PM10, NO₂, SO₂, ozone, CO and lead.
- The National Ambient Air Quality Standards are set by the CPCB.
- The Air Quality Index has 6 categories.
- Sources in the Indo-Gangetic plain: vehicles, industry, construction dust, burning of crop stubble (Punjab, Haryana), biomass cooking fuel and brick kilns. The plain's geography traps pollution in winter (temperature inversion).
- Responses:
- NCAP (2019): up to a 40% cut by 2025–26 in non-attainment cities;
- BS-VI fuel standards (2020);
- the Graded Response Action Plan in Delhi–NCR;
- Ujjwala LPG.
- Patna, Muzaffarpur and Gaya often rank among India's most polluted cities in winter.
Water pollution
- Measured as BOD and COD; coliforms are a key indicator.
- Namami Gange (2014) cleans the Ganga; the National Mission for Clean Ganga runs it.
- Groundwater:
- Arsenic in the Ganga plains, including Bihar's Bhojpur, Buxar, Patna, Vaishali and Bhagalpur.
- Fluoride in Rajasthan, and in parts of Jharkhand (Palamu, Garhwa) and Bihar (Gaya, Nawada).
- Nitrate from fertilisers.
- Plastics: Plastic Waste Management Rules (2016, amended); ban on identified single-use plastics (2022); EPR.
Waste
- Solid Waste Management Rules (2016).
- E-Waste Rules (2022, with EPR).
- Biomedical and hazardous waste rules.
- Fly ash use from thermal plants.
- Mining waste and acid mine drainage (Jharkhand).
Key international conventions
| Convention | Subject | Year |
|---|---|---|
| Ramsar | Wetlands | 1971 |
| CITES | Trade in endangered species | 1973 |
| CMS (Bonn) | Migratory species | 1979 |
| Vienna / Montreal | Ozone | 1985 / 1987 |
| Basel | Hazardous waste movement | 1989 |
| CBD (Rio) | Biodiversity; Cartagena (biosafety, 2000) and Nagoya (access and benefit sharing, 2010) protocols; Kunming–Montreal GBF (2022), "30 × 30" | 1992 |
| UNCCD | Desertification; India's land restoration target of 26 million ha by 2030 | 1994 |
| Rotterdam | Prior informed consent for chemicals | 1998 |
| Stockholm | Persistent Organic Pollutants | 2001 |
| Minamata | Mercury | 2013 |
| BBNJ (High Seas Treaty) | Marine biodiversity beyond national jurisdiction; came into force January 2026 | 2023 |
Exam tip: Prelims pairs a convention with its subject; learn the table above. Mains asks for climate justice and India's position. Use CBDR, per capita emissions (India's are about a third of the world average) and the Panchamrit targets.
Mains practice
Write each answer in the word limit your exam sets. Use the notes above for the structure: introduction, body with facts and examples, a short way forward.
- Explain the principle of common but differentiated responsibilities. How has India used it in climate negotiations? (150 words)
- Air pollution in the Indo-Gangetic plain is a public health emergency. Discuss its causes and solutions. (250 words)