BharatNotes
Overview
Marine pollution and ozone depletion represent two of the most significant threats to Earth's environmental systems. Approximately 80% of marine pollution originates from land-based sources -- agricultural runoff, plastic waste, sewage, and industrial discharges -- threatening marine biodiversity, fisheries, and human health. Ozone depletion, driven by man-made chemicals like CFCs, led to one of the most successful international environmental agreements ever -- the Montreal Protocol (1987). For UPSC, this topic spans GS3 (Environment) and frequently appears in both Prelims (conventions, protocols, dates) and Mains (policy analysis, India's role, global cooperation).
This chapter also provides a comprehensive reference table of all major global environmental conventions -- a high-yield Prelims resource.
Marine Pollution
Sources of Marine Pollution
| Source Category | Contribution | Examples |
|---|---|---|
| Land-based sources | ~80% of marine pollution | Agricultural runoff (fertilisers, pesticides), untreated sewage, industrial effluents, plastic waste, urban stormwater |
| Ship-based sources | ~20% | Oil spills, ballast water discharge, anti-fouling paints, garbage dumping, sewage from vessels |
| Atmospheric deposition | Significant but harder to quantify | Mercury, nitrogen compounds, and persistent organic pollutants deposited from the atmosphere onto ocean surfaces |
| Deep-sea activities | Emerging concern | Deep-sea mining (polymetallic nodules, manganese crusts), seabed drilling |
Types of Marine Pollution
| Type | Detail |
|---|---|
| Oil pollution | Oil spills from tanker accidents, offshore drilling blowouts, routine operational discharges; oil coats marine organisms, destroys feather insulation in seabirds, smothers coral reefs; major spills: Deepwater Horizon (2010, Gulf of Mexico), Exxon Valdez (1989, Alaska) |
| Plastic pollution / Microplastics | An estimated 11 million tonnes of plastic enter oceans annually; microplastics (<5mm) from degradation of larger plastics, synthetic textiles (microfibres), and cosmetics; ingested by marine organisms from zooplankton to whales; enter the human food chain through seafood |
| Eutrophication / Dead zones | Excess nitrogen and phosphorus from agricultural runoff and sewage cause algal blooms; decomposition of algae depletes dissolved oxygen, creating hypoxic "dead zones" where marine life cannot survive; over 500 dead zones globally, including the Gulf of Mexico |
| Ghost nets | Abandoned, lost, or discarded fishing gear (ALDFG); continues to trap and kill marine life for years ("ghost fishing"); estimated 640,000 tonnes of fishing gear enter oceans annually |
| Heavy metals | Mercury, lead, cadmium from industrial discharge; bioaccumulate through the food chain; mercury in fish is a major human health concern (Minamata disease) |
| Noise pollution | Ship engines, sonar, seismic surveys for oil exploration disrupt cetacean (whale, dolphin) communication, navigation, and feeding |
For Mains: Marine pollution is a classic "tragedy of the commons" -- the oceans are shared by all nations but effectively governed by none. Discuss the challenges of regulating marine pollution in international waters, the role of UNCLOS, and the failure of INC-5 to produce a binding Global Plastics Treaty.
International Framework for Marine Pollution
MARPOL Convention
| Feature | Detail |
|---|---|
| Full name | International Convention for the Prevention of Pollution from Ships |
| Adopted | 2 November 1973 at IMO; Protocol of 1978 added after tanker accidents |
| Entry into force | 2 October 1983 |
| Governing body | International Maritime Organization (IMO) |
| Scope | Covers pollution from ships -- oil, noxious liquid substances, harmful substances in packaged form, sewage, garbage, and air emissions |
| 6 Annexes | I: Oil; II: Noxious Liquid Substances; III: Harmful Substances in Packaged Form; IV: Sewage; V: Garbage; VI: Air Pollution |
| Limitation | Addresses ship-sourced pollution only; does NOT regulate land-based sources (which account for 80% of marine pollution) |
Global Plastics Treaty Negotiations
| Feature | Detail |
|---|---|
| Mandate | UNEA Resolution 5/14 (March 2022) -- established an Intergovernmental Negotiating Committee (INC) to develop a legally binding instrument on plastic pollution |
| INC-5 (Busan, South Korea) | 25 November -- 1 December 2024; the fifth and final scheduled negotiating session |
| Outcome | Failed to reach agreement; delegates could not bridge disagreements on production caps, chemical restrictions, and funding mechanisms |
| Key divide | "High Ambition Coalition" (EU, UK, Canada, many African/Pacific nations) wanted binding production reduction targets; oil-producing nations opposed production caps |
| Next steps | Negotiations to resume in 2025 (INC-5.2); Chair's Text serves as the basis for continued talks |
| Significance | If adopted, would be the first legally binding global treaty specifically addressing plastic pollution across the full lifecycle |
India's Ban on Single-Use Plastics
| Feature | Detail |
|---|---|
| Effective date | 1 July 2022 |
| Banned items | 19 identified single-use plastic items with low utility and high littering potential: ear buds with plastic sticks, balloon sticks, plastic flags, candy sticks, ice-cream sticks, polystyrene (thermocol) for decoration, plates, cups, glasses, cutlery (forks, spoons, knives), straws, trays, wrapping/packing films around sweet boxes, invitation cards, cigarette packets, plastic/PVC banners <100 micron, stirrers |
| Carry bags | Bags <75 micron banned; bags <120 micron banned from 31 December 2022 |
| Not covered | Plastic bottles, multilayer packaging, and other plastic products -- these are regulated under Extended Producer Responsibility (EPR) |
| Enforcement | Mixed; enforcement stronger in urban areas; rural and informal sector compliance remains a challenge |
Ozone Depletion
The Ozone Layer
| Feature | Detail |
|---|---|
| Location | Stratosphere, approximately 15--35 km above Earth's surface |
| Function | Absorbs ~97--99% of the sun's harmful ultraviolet-B (UV-B) radiation, protecting life on Earth from skin cancer, cataracts, immune suppression, and damage to crops and marine ecosystems |
| Ozone molecule | O3 -- three oxygen atoms; formed when UV radiation splits O2, and the free oxygen atom combines with another O2 molecule |
| Measurement | Measured in Dobson Units (DU); normal ozone column: ~300 DU; "ozone hole" = region where ozone falls below 220 DU |
Ozone-Depleting Substances (ODS)
| Substance | Use | Ozone Depleting Potential (ODP) | Global Warming Potential (GWP) |
|---|---|---|---|
| CFCs (Chlorofluorocarbons) | Refrigeration, air conditioning, aerosol propellants, foam blowing | High (ODP = 0.6--1.0) | High (GWP = 4,750--14,400) |
| HCFCs (Hydrochlorofluorocarbons) | Transitional replacements for CFCs; refrigeration | Lower (ODP = 0.01--0.12) | Moderate to High |
| Halons | Fire extinguishers | Very High (ODP = 3--10) | Moderate |
| Carbon tetrachloride | Industrial solvent | ODP = 1.1 | Low |
| HFCs (Hydrofluorocarbons) | Replacements for CFCs/HCFCs in refrigeration | Zero ODP (do NOT deplete ozone) | Very High (GWP = 12--14,800); potent greenhouse gases |
For Prelims: CFCs have high ODP AND high GWP. HFCs have zero ODP but very high GWP -- they do not deplete ozone but are powerful greenhouse gases. The Kigali Amendment addresses HFCs specifically.
Montreal Protocol, 1987
| Feature | Detail |
|---|---|
| Adopted | 16 September 1987 (celebrated as International Day for the Preservation of the Ozone Layer) |
| Entry into force | 1 January 1989 |
| Ratification | 198 parties -- the first treaty to achieve universal ratification; often called the most successful multilateral environmental agreement in history |
| Objective | Phase out the production and consumption of ozone-depleting substances |
| Mechanism | Differentiated timelines for developed and developing countries (Article 5 countries get a grace period of 10 years) |
| Multilateral Fund | Established in 1991 to provide financial and technical assistance to developing countries for ODS phase-out |
| Impact | 99% of ODS phased out globally; without the Montreal Protocol, the ozone layer would have collapsed by the 2060s; prevented an estimated 2 million skin cancer cases annually by 2030 |
| Ozone recovery | The ozone hole over Antarctica is slowly healing; full recovery expected by ~2066 (Antarctic), ~2045 (Arctic), ~2040 (rest of the world) -- per WMO/UNEP Scientific Assessment (2022) |
Kigali Amendment, 2016
| Feature | Detail |
|---|---|
| Adopted | 15 October 2016 at the 28th Meeting of Parties to the Montreal Protocol, in Kigali, Rwanda |
| Entry into force | 1 January 2019 |
| Objective | Phase down production and consumption of HFCs (hydrofluorocarbons) by 80--85% by the late 2040s |
| Why | HFCs were introduced as replacements for CFCs/HCFCs (zero ODP); but their extremely high GWP makes them potent greenhouse gases; if unchecked, HFC emissions could add up to 0.5 degrees Celsius to global warming by 2100 |
| Country groups | Group 1 (developed): baseline 2011--2013; phase-down starts 2019; Group 2 (China, etc.): baseline 2020--2022; phase-down starts 2024; Group 3 (India, Pakistan, Gulf states, etc.): baseline 2024--2026; phase-down starts 2032 |
| India's commitment | Ratified on 27 September 2021; phase-down in 4 steps: 10% by 2032, 20% by 2037, 30% by 2042, 85% by 2047 |
| Climate impact | Full implementation of Kigali Amendment could avoid up to 0.5 degrees Celsius of global warming by end of century |
For Prelims: Montreal Protocol: 1987; universal ratification (198 parties); most successful MEA. Kigali Amendment: 2016; HFC phase-down (NOT phase-out); India ratified September 2021; India's phase-down starts 2032, target 85% reduction by 2047.
Global Environmental Conventions — Comprehensive Reference Table
Biodiversity and Wildlife Conventions
| Convention | Year Adopted | Objective | India's Status |
|---|---|---|---|
| Ramsar Convention (Convention on Wetlands) | 1971 (Ramsar, Iran) | Conservation and wise use of wetlands and their resources | Signatory since 1982; 98 Ramsar sites as of February 2026 (3rd highest globally); Tamil Nadu leads with 20 sites |
| CITES (Convention on International Trade in Endangered Species) | 1973 (Washington, DC) | Regulate international trade in specimens of wild animals and plants to ensure trade does not threaten their survival | Party since 1976; 3 Appendices: I (banned), II (regulated), III (monitored) |
| CMS / Bonn Convention (Convention on Migratory Species) | 1979 (Bonn, Germany) | Conservation of migratory species and their habitats; promotes international cooperation | India is a party; relevant for migratory birds (Central Asian Flyway), marine turtles, dugongs |
| CBD (Convention on Biological Diversity) | 1992 (Rio Earth Summit) | Conservation of biological diversity, sustainable use, fair and equitable sharing of benefits from genetic resources | India ratified 1994; enacted Biological Diversity Act, 2002; Kunming-Montreal Global Biodiversity Framework (GBF) adopted December 2022 -- 30x30 target |
Chemicals and Waste Conventions
| Convention | Year Adopted | Objective | India's Status |
|---|---|---|---|
| Basel Convention | 1989 (Basel, Switzerland) | Control transboundary movements of hazardous wastes and their disposal; prevent dumping of hazardous waste in developing countries | India ratified June 1992 |
| Rotterdam Convention | 1998 (Rotterdam, Netherlands) | Prior Informed Consent (PIC) procedure for certain hazardous chemicals and pesticides in international trade | India is a party; entered into force 2004 |
| Stockholm Convention | 2001 (Stockholm, Sweden) | Eliminate or restrict production and use of Persistent Organic Pollutants (POPs) -- chemicals that persist in the environment, bioaccumulate, and are toxic | India ratified January 2006; initial list of 12 POPs ("dirty dozen") expanded to 30+ |
| Minamata Convention | 2013 (Kumamoto, Japan) | Protect human health and environment from anthropogenic emissions and releases of mercury and mercury compounds | India ratified February 2018; named after Minamata disease (mercury poisoning in Japan, 1950s) |
Climate and Desertification Conventions
| Convention | Year Adopted | Objective | India's Status |
|---|---|---|---|
| UNFCCC | 1992 (Rio Earth Summit) | Stabilise greenhouse gas concentrations to prevent dangerous anthropogenic interference with the climate system | India ratified 1993; Paris Agreement (2015) -- India's NDC targets |
| UNCCD (UN Convention to Combat Desertification) | 1994 | Combat desertification and mitigate effects of drought through national action programmes | India ratified 1996; hosted COP-14 in New Delhi, September 2019; committed to restoring 26 million hectares of degraded land by 2030 |
Marine Conventions
| Convention | Year Adopted | Objective | India's Status |
|---|---|---|---|
| UNCLOS (UN Convention on the Law of the Sea) | 1982 | Comprehensive legal framework governing all uses of oceans and their resources; defines maritime zones (territorial sea, EEZ, continental shelf, high seas) | India ratified 1995 |
| MARPOL | 1973/78 | Prevention of pollution from ships | India is a party |
For Prelims: Memorise the convention table -- year, objective, India's status. High-frequency: Ramsar (1971, 98 sites), CITES (1973, 3 Appendices), CBD (1992, Biological Diversity Act 2002), Basel (1989, hazardous waste), Stockholm (2001, POPs), Minamata (2013, mercury, India ratified 2018), Montreal Protocol (1987, ODS), Kigali Amendment (2016, HFCs).
Marine Dead Zones and Eutrophication
| Feature | Detail |
|---|---|
| What | Hypoxic zones (dissolved oxygen <2 mg/L) where most marine life cannot survive |
| Cause | Excess nutrients (nitrogen, phosphorus) from agricultural fertiliser runoff and sewage trigger massive algal blooms; when algae die and decompose, bacteria consume dissolved oxygen |
| Scale | Over 500 documented dead zones globally; the Gulf of Mexico dead zone covers ~15,000 sq km annually |
| India | Localised dead zones reported off the coasts of Gujarat, Maharashtra, and Kerala; linked to industrial effluents and sewage discharge |
| Solution | Reduce nutrient runoff (precision agriculture, buffer zones), treat sewage before discharge, restore coastal wetlands (natural nutrient filters) |
India and Marine Pollution — Key Initiatives
| Initiative | Detail |
|---|---|
| National Plan for Oil Pollution Preparedness | Indian Coast Guard is the Central Coordinating Authority for oil spill response; National Oil Spill Disaster Contingency Plan (NOS-DCP) in place |
| Coastal Ocean Monitoring and Prediction System (COMAPS) | MoES programme for monitoring marine water quality along India's coast |
| Integrated Coastal Zone Management Project (ICZMP) | World Bank-assisted project for sustainable management of India's coastal resources; implemented in Gujarat, Odisha, and West Bengal |
| Swachh Sagar, Surakshit Sagar | Beach clean-up campaign launched in 2022; aims to remove marine litter and raise awareness about ocean pollution |
| National Centre for Sustainable Coastal Management (NCSCM) | Chennai-based institute under MoEFCC; prepares Coastal Zone Management Plans, conducts research on coastal vulnerability |
Ozone Recovery — Current Status
| Parameter | Detail |
|---|---|
| Antarctic ozone hole | Continues to appear each spring (September-October); size has been slowly decreasing since 2000 |
| Recovery timeline | WMO/UNEP Scientific Assessment (2022): ozone layer expected to recover to 1980 levels by ~2066 over Antarctica, ~2045 over Arctic, ~2040 over rest of the world |
| Success metric | 99% of ozone-depleting substances have been phased out globally under the Montreal Protocol |
| New threats | Some studies detect unexpected emissions of banned ODS (CFC-11 emissions detected from eastern Asia in 2018-19); very short-lived substances (VSLS like dichloromethane) not covered by Montreal Protocol may delay recovery |
| Climate co-benefit | ODS are also potent greenhouse gases; their phase-out has avoided an estimated 135 billion tonnes of CO2-equivalent emissions through 2025 |
Vienna Convention for the Protection of the Ozone Layer, 1985
| Feature | Detail |
|---|---|
| Adopted | 22 March 1985 in Vienna, Austria |
| Entry into force | 22 September 1988 |
| Significance | Framework convention that established the principle of international cooperation to protect the ozone layer; led to the adoption of the Montreal Protocol (1987) |
| Parties | 198 (universal ratification, like the Montreal Protocol) |
| Key provision | Obligates parties to take "appropriate measures" to protect the ozone layer; promotes research, monitoring, and information exchange; does NOT set specific ODS phase-out targets (that was left to the Montreal Protocol) |
Deep-Sea Mining — An Emerging Concern
| Feature | Detail |
|---|---|
| What | Extraction of mineral resources from the ocean floor -- polymetallic nodules (manganese, nickel, cobalt, copper), cobalt-rich crusts, and polymetallic sulphides from hydrothermal vents |
| Regulatory body | International Seabed Authority (ISA), established under UNCLOS |
| India's involvement | India holds exploration rights for polymetallic nodules in the Central Indian Ocean Basin (allocated by ISA); India's research vessel Samudra Ratnakar has conducted multiple expeditions |
| Environmental risks | Destruction of deep-sea ecosystems (some of the least understood on Earth), sediment plumes, noise, loss of species not yet discovered |
| Status | No commercial deep-sea mining has begun; ISA is developing a mining code; several Pacific Island nations have called for a moratorium |
Coral Reef Bleaching and Ocean Acidification
| Feature | Detail |
|---|---|
| Coral bleaching | Rising ocean temperatures cause corals to expel symbiotic algae (zooxanthellae), turning white; prolonged bleaching kills corals; 2023--2024 saw the 4th global mass bleaching event, affecting >75% of the world's reefs |
| Ocean acidification | Oceans absorb ~30% of human-emitted CO2; dissolved CO2 forms carbonic acid, lowering ocean pH from pre-industrial 8.2 to current ~8.1; threatens calcifying organisms (corals, shellfish, plankton) |
| India's coral reefs | Major reef systems: Gulf of Kutch, Gulf of Mannar, Andaman & Nicobar Islands, Lakshadweep; all experiencing bleaching events |
| Protection | Gulf of Mannar Marine National Park; Mahatma Gandhi Marine National Park (Andaman); Coral Reef Monitoring Programme by MoEFCC |
UPSC Relevance
Prelims Focus Areas
- Marine pollution: 80% from land-based sources; microplastics, eutrophication, dead zones
- MARPOL: 1973/78; 6 Annexes; IMO; ship-based pollution only
- Single-use plastics ban: 1 July 2022; 19 items; carry bags <120 micron banned from December 2022
- INC-5 Busan: failed to produce Global Plastics Treaty (2024)
- Ozone layer: stratosphere, 15-35 km; measured in Dobson Units
- CFCs: high ODP + high GWP; HFCs: zero ODP + very high GWP
- Montreal Protocol: 1987; universal ratification; 99% ODS phased out
- Kigali Amendment: 2016; HFC phase-down; India ratified September 2021; starts 2032
- Convention table: Ramsar (1971), CITES (1973), CMS (1979), CBD (1992), Basel (1989), Rotterdam (1998), Stockholm (2001), Minamata (2013)
- Ramsar sites in India: 98 (February 2026); Tamil Nadu = most sites (20)
Mains Focus Areas
- Marine plastic pollution -- scale, impact, and the failure of global governance (INC-5)
- Ozone layer protection as a model for international cooperation -- lessons from Montreal Protocol for climate change negotiations
- Kigali Amendment -- how phasing down HFCs can contribute to climate goals; India's timeline and challenges
- Eutrophication and dead zones -- link to agricultural practices and the need for integrated land-ocean management
- Deep-sea mining -- resource opportunity vs environmental risk; India's position
- Effectiveness of India's single-use plastics ban -- implementation challenges
- Environmental conventions -- India's compliance record and institutional capacity
Vocabulary
Microplastics
- Pronunciation: /ˌmaɪkroʊˈplæstɪks/
- Definition: Tiny plastic particles less than 5 millimetres in diameter, originating from the fragmentation of larger plastic debris, industrial processes (plastic pellets or "nurdles"), synthetic textile fibres released during washing, and microbeads in cosmetics -- pervasive in marine environments, freshwater systems, soil, and even the atmosphere, ingested by organisms at every trophic level and entering the human food chain.
- Origin: From Greek mikros (μικρός, "small") + English plastics (from Greek plastikos, "capable of being moulded"); the term gained scientific and public attention in the early 2000s when marine researchers documented the ubiquity of microscopic plastic fragments in ocean samples, leading to growing concern about their ecological and human health impacts.
Eutrophication
- Pronunciation: /juːˌtrɒfɪˈkeɪʃən/
- Definition: The process by which a body of water becomes excessively enriched with nutrients -- primarily nitrogen and phosphorus from agricultural runoff, sewage, and industrial discharge -- leading to dense algal blooms that block sunlight, and whose subsequent decomposition by bacteria depletes dissolved oxygen, creating hypoxic "dead zones" where aerobic marine life cannot survive.
- Origin: From Greek eutrophia (εὐτροφία, "adequate nutrition"), from eu- ("well, good") + trophē ("nourishment"); originally a neutral ecological term describing nutrient-rich water bodies, it acquired its negative connotation in the mid-20th century as human-caused nutrient loading began creating massive dead zones in lakes, estuaries, and coastal waters worldwide.
Key Terms
Montreal Protocol
- Pronunciation: /ˌmɒntriˈɔːl ˈproʊtəkɒl/
- Definition: An international treaty adopted on 16 September 1987 under the Vienna Convention for the Protection of the Ozone Layer, committing its 198 parties to the progressive phase-out of ozone-depleting substances (CFCs, HCFCs, halons, carbon tetrachloride, and others) through legally binding schedules with differentiated timelines for developed and developing countries -- widely regarded as the most successful multilateral environmental agreement in history, having achieved 99% ODS phase-out and averted the collapse of the ozone layer.
- Context: The Montreal Protocol is the first treaty to achieve universal ratification; it established the Multilateral Fund (1991) to assist developing countries; its Kigali Amendment (2016) expanded the treaty's scope to phase down HFCs, linking ozone protection to climate change mitigation; ozone recovery is on track, with full healing expected by 2040 (global) to 2066 (Antarctic).
- UPSC Relevance: GS3 (Environment). Prelims: 1987, universal ratification, 99% ODS phased out, ozone recovery timeline. Mains: Montreal Protocol as a model for international environmental cooperation; why was it more successful than climate negotiations? Discuss the Kigali Amendment's significance for climate change mitigation.
Kigali Amendment
- Pronunciation: /kɪˈɡɑːli əˈmɛndmənt/
- Definition: An amendment to the Montreal Protocol adopted on 15 October 2016 in Kigali, Rwanda, mandating a global phase-down of hydrofluorocarbons (HFCs) by 80-85% by the late 2040s -- HFCs, while having zero ozone-depleting potential, are extremely potent greenhouse gases with global warming potentials up to 14,800 times that of CO2, making the Kigali Amendment a significant climate change mitigation instrument.
- Context: India ratified the Kigali Amendment on 27 September 2021; India belongs to Group 3 (baseline 2024-2026, phase-down starting 2032); India's schedule: 10% reduction by 2032, 20% by 2037, 30% by 2042, 85% by 2047; full implementation could avoid up to 0.5 degrees Celsius of warming by 2100; key challenge for India is the transition to low-GWP alternatives in the rapidly growing refrigeration and air conditioning sector.
- UPSC Relevance: GS3 (Environment, Climate Change). Prelims: 2016, Kigali Rwanda, HFC phase-down (not phase-out), India ratified September 2021, India's timeline (2032-2047). Mains: discuss the Kigali Amendment's dual role in ozone protection and climate mitigation; challenges for India's refrigeration industry in transitioning to low-GWP alternatives.
Sources: IMO (MARPOL Convention), UNEP (Montreal Protocol, Kigali Amendment, marine pollution data), WMO/UNEP Scientific Assessment of Ozone Depletion (2022), pib.gov.in (India ratification of Kigali Amendment, single-use plastics ban), MoEFCC (Plastic Waste Management Rules), UNCLOS, International Seabed Authority, UNEA (INC mandate for plastics treaty), UN News (INC-5 Busan outcome), Ramsar Convention Secretariat, CBD Secretariat, Basel/Rotterdam/Stockholm Conventions
