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University-wide Ability Enhancement Course Pool
Complete exam notes for the Delhi University Environmental Studies (AEC) paper: Units 5 to 7 explained question by question, the four-paper question bank analysed by frequency, and a one-page revision sheet.
This paper is mostly repeat questions. The same short notes, differences and case studies come back every session, so read the priority table before anything else.
| Section | What you get | Marks | Attempt |
|---|---|---|---|
| A · Q1 | Full forms (5) + True/False or Fill in the blanks (5) | 5 + 5 = 10 | Compulsory in the book's pattern |
| A · Q2 | Short notes, 2.5 marks each | 2.5 × 4 = 10 | Any 4 of 5 |
| A · Q3 | Differentiate between, 5 marks each | 5 × 2 = 10 | Any 2 of 3 |
| A · Q4 | 10-mark essay (climate, biodiversity, culture) | 10 | Any 1 or 2, as asked |
| B · Q5 to Q7 | Case studies: nuclear energy, hydropower, population growth, biodiversity threats | 10 × 2 = 20 | Any 2 |
Exam tipRegular students write Part A (30 marks). SOL students also write Part B (20) and Part C (20). Question 1 is compulsory.
| Topic | Question type | Priority |
|---|---|---|
| Solid waste segregation and dustbin colours | Long answer, T/F | ★★★ appeared in all 4 papers |
| Ecosystem services (provisioning, regulating, cultural) | Differentiate, long answer | ★★★ 3 papers |
| Chipko and Appiko movements | Short note, long answer | ★★★ 3 papers |
| Water crisis and groundwater depletion | Long answer | ★★★ 3 papers |
| Speech-format questions (SDGs, ozone, ecosystem) | Long answer | ★★★ 3 papers |
| Kaveri river water dispute | T/F, long answer | ★★★ 2 papers |
| Pioneer species | Fill in the blanks | ★★★ 2 papers |
| Bhopal Gas Tragedy | Short note | ★★★ 2 papers |
| Desertification | Short note, long answer | ★★★ 2 papers |
| Nuclear energy, fossil fuels, hydrosphere, abiotic component | Definitions, FIB | ★★★ 2 papers |
| Climate change and SDGs | Long answer | ★★★ 2 papers |
| Renewable energy (India initiatives) | Long answer | ★★★ 2 papers |
| Sustainability and sustainable development | Long answer | ★★★ 2 papers |
| Air pollution (sources, impacts, Delhi) | Long answer | ★★★ 2 papers |
The book's PYQ list and the two January 2025 papers repeat the same ten short notes.
| Paper set | Short notes asked |
|---|---|
| Earlier PYQ list | Endemic species, Biological invasions, Swachh Bharat Abhiyan, Biodiversity, Global warming, Endangered species, Acid rain, Carbon footprints, Montreal Protocol, Sacred groves |
| January 2025, paper 1 | Endemic species, Biological invasions, Global warming, Biodiversity, Swachh Bharat Abhiyan |
| January 2025, paper 2 | Endangered species, Carbon footprints, Montreal Protocol, Sacred groves, Acid rain |
Exam tipAll ten are ready-made 2.5-mark notes. Learn the five-line version of each in this file and you have most of Q2.
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Syllabus: causes of climate change, global warming, ozone depletion and acid rain; international agreements; sustainable development goals and India's climate plan; environment laws in India.
Climate change is the long-term change in the average weather of the Earth (temperature, rainfall, wind, seasons). Today it is driven mainly by human activity that raises greenhouse gases in the atmosphere.
| Cause | How it adds to climate change |
|---|---|
| Burning fossil fuels | Coal, petroleum and gas in industry, power plants and vehicles release large amounts of CO₂ |
| Deforestation | Fewer trees to absorb CO₂ |
| Industrialisation | CO₂, methane and nitrous oxide from factories |
| Agriculture | Chemical fertilisers and paddy fields release nitrous oxide and methane |
| Urbanisation and population growth | More energy use, waste and vehicle emissions |
| CFCs and other chemicals | From refrigerators, air conditioners and aerosol sprays |
Global warming is the gradual rise in the average temperature of the Earth's atmosphere because greenhouse gases trap heat that would otherwise escape to space.
Contribution of gases to global warming
Share of global warming by gas (approximate, as given in the book). Carbon dioxide: 60, Methane: 17, CFCs: 13, Nitrous oxide: 6
| Gas | Share | Main sources |
|---|---|---|
| Carbon dioxide (CO₂) | about 60% | Fossil fuels, vehicles, industry, deforestation |
| Methane (CH₄) | about 15 to 20% | Paddy fields, landfills, livestock. Traps more heat than CO₂ |
| CFCs | about 12 to 15% | Air conditioners, refrigerators, aerosols. Long atmospheric life |
| Nitrous oxide (N₂O) | about 6% | Fertilisers, industry, combustion |
| Water vapour | variable | Natural. Amplifies warming once temperature rises |
Effects of global warming
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Effects on agriculture (a common 5-mark point list)
Irregular rainfall causes floods and droughts that destroy crops.
Lower yield of wheat and rice as temperature rises.
More pests and plant diseases in a warmer climate.
Water scarcity for irrigation as glaciers shrink.
The ozone layer sits in the stratosphere and blocks harmful UV rays. Depletion is its thinning caused by CFCs, halons and similar chemicals.
| Impact on | Effect |
|---|---|
| Human health | Skin cancer, eye cataracts, weaker immune system |
| Crops and plants | UV reduces photosynthesis and yield |
| Marine life | Phytoplankton harmed, aquatic food chain disturbed |
| Environment | Climate imbalance and biodiversity loss |
Exam tipThe ozone hole is worst over the poles, especially Antarctica, not the equator. This has been asked as a True/False.
Acid rain is rain that contains acids, formed when sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) from industries, vehicles and power plants mix with water vapour in the air.
Causes: burning coal and petroleum, vehicle exhaust, thermal power plants and factories.
Crops and forests: damaged leaves, lower soil fertility.
Aquatic life: acid water kills fish in lakes and rivers.
Soil: leaching of calcium and magnesium.
Buildings and monuments: corrodes marble and limestone, for example the Taj Mahal.
| Natural causes | Anthropogenic (human) causes | |
|---|---|---|
| Energy | Solar variability: Milankovitch cycles (eccentricity, axial tilt, precession) and the 11-year sunspot cycle | Fossil fuels: electricity, transport, industry, heating |
| Land | Geological processes: plate tectonics, mountains. The Himalayas shape the Asian monsoon | Deforestation and land-use change: releases stored CO₂, loses carbon sinks |
| Air and sea | Volcanic eruptions: ash and SO₂ cause temporary cooling. Mount Tambora 1815 gave the "Year Without a Summer" | Industrial processes: cement, steel, chemicals |
| Oceans | Ocean circulation: El Niño Southern Oscillation (ENSO) changes rain and temperature worldwide | Agriculture and livestock: methane from cattle, nitrous oxide from fertiliser |
| Gases | Natural emissions: methane from wetlands and thawing permafrost, CO₂ from volcanoes and forest fires | Waste: methane from landfills and wastewater plants |
| Other | Refrigerants (HFCs, HCFCs), land degradation, urbanisation (urban heat island), transport, consumption patterns |
Exam tipThe natural causes explain old climate swings. The anthropogenic causes explain the present rapid warming. Say so in your conclusion.
Agriculture in India depends on rain, temperature and soil, so farmers are very exposed to environmental stress.
A. Environmental issues behind rising farmer suicides
| Issue | Why it hurts the farmer |
|---|---|
| Rising temperature | A 1°C rise in the growing season is linked to more suicides. Crops fail |
| Erratic rain and drought | Rain-fed small farms lose income |
| Floods and extreme weather | Standing crops and stored grain destroyed, often uninsured |
| Falling soil fertility | Fertiliser costs rise, debt grows |
| Water scarcity | Groundwater falls, irrigation is inadequate |
| Pests and disease | Higher pesticide spending |
| Economic stress | Repeated failure leads to debt, depression, insecurity |
B. What the government should do
Irrigation: canals, drip irrigation, rainwater harvesting, watershed management.
Climate-resilient farming: drought and heat tolerant varieties, crop diversification.
Fair price and income support: MSP, timely procurement, direct income support.
Cheap credit and debt relief through cooperative and rural banks.
Crop insurance with faster claim settlement.
Sustainable farming: organic methods, soil conservation, integrated pest management.
Education and information: training, demonstration farms, digital weather and market data.
Alternative livelihoods: mixed farming, agro-based cottage industry.
Wetlands are lands that are permanently or seasonally saturated with water: ponds, lakes, rivers, estuaries, mangroves, marshes, swamps, reservoirs.
Types: marine (coasts), estuarine (deltas, tidal marshes, mangroves), lacustrine (lakes), riverine (rivers, streams), palustrine (marshes, swamps, bogs).
| For biodiversity | For water conservation |
|---|---|
| High productivity and nutrient recycling | Water purification: natural filters trapping sediment and pollutants |
| Breeding and nursery ground for fish, amphibians, birds | Flood control: act like a sponge and release water slowly |
| Habitat for migratory birds: Bharatpur, Little Rann of Kutch | Groundwater recharge through percolation |
| Shelter for endangered species: Sangai deer (Loktak Lake), Sarus crane, Gangetic river dolphin | Water storage in the rains, release in drought |
| About 290 fish species in Western Ghats freshwater | Climate regulation by carbon sequestration |
International treaty for wetland conservation, signed 2 February 1971 at Ramsar, Iran. Celebrated as World Wetlands Day (2 February).
Full name: Convention on Wetlands of International Importance.
Three pillars: (1) wise use of all wetlands, (2) designation and management of Ramsar Sites, (3) international cooperation on shared wetlands and migratory species.
Covers lakes, rivers, marshes, peatlands, mangroves, estuaries, coral reefs and human-made wetlands such as rice fields, reservoirs, fish ponds, salt pans.
Bodies: Conference of Contracting Parties (COP), Standing Committee, Scientific and Technical Review Panel (STRP), Secretariat based at IUCN, Switzerland.
Exam tipThe book gives 26 Ramsar sites for India. That number is old and has grown a lot since, so quote the latest figure if you know it.
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| Agreement | Year and place | Objective | Key facts to remember |
|---|---|---|---|
| Earth Summit (UNCED) | 3 to 14 June 1992, Rio de Janeiro | Balance development with environment protection | Outcomes: Rio Declaration, Agenda 21, Forest Principles. Opened UNFCCC, CBD, UNCCD for signature. Led to Kyoto and Paris |
| UNFCCC | Adopted 9 May 1992, in force 21 March 1994 | Stabilise greenhouse gases, prevent dangerous interference with climate | Framework convention with non-binding targets. About 197 parties. Yearly COP. Secretariat in Bonn |
| CBD | Opened 1992, in force 29 December 1993 | Conserve biodiversity, use it sustainably, share benefits fairly | COP every two years. Protocols: Cartagena (biosafety) and Nagoya (access and benefit sharing). About 194 members |
| Ramsar | 1971, Ramsar Iran | Conserve and wisely use wetlands | See Q8 |
| Chemical Weapons Convention | In force 29 April 1997 | Ban development, production, stockpiling, use of chemical weapons | Run by OPCW, The Hague. 193 states parties. Over 96% of declared stock destroyed |
| UNEP | 1972, after Stockholm | Coordinate UN environmental work | HQ Nairobi. Publishes Global Environment Outlook (GEO). Also called UN Environment |
| CITES | Drafted 1963 (IUCN), opened 1973, in force 1 July 1975 | Make sure trade in wild species does not threaten survival | Also the Washington Convention. Legally binding. Over 35,000 species in three Appendices. Licences for import, export, re-export. HQ Geneva, Secretariat run by UNEP. India hosted the 3rd CoP in 1981 |
| Montreal Protocol | Adopted 16 September 1987, in force 1 January 1989 | Phase out ozone depleting substances | Covers CFCs, halons, carbon tetrachloride, methyl chloroform. Phase-out by 2000 (2005 for some). Ozone expected back to 1980 levels by 2050 to 2070. Called the most successful environmental agreement |
| Kyoto Protocol | Adopted 1997 Kyoto, in force 2005 | Cut greenhouse gas emissions | Developed countries only. Average 5% below 1990 levels, period 2008 to 2012. Gases: CO₂, CH₄, N₂O, HFCs, PFCs, SF₆. Principle: Common but Differentiated Responsibility. Doha Amendment (8 Dec 2012) gave the 2013 to 2020 period. First legally binding climate treaty |
| Vienna Convention | 1985 | Framework for ozone protection | Parent treaty of the Montreal Protocol |
| Kigali Amendment | 2016 | Phase down HFCs | Extends the Montreal Protocol to potent greenhouse gases |
Exam tip"Comment on" and "Write short notes" questions on these conventions usually want year, objective, two key features and one body or protocol. The table above is exactly that.
Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. It brings economic and social change without disturbing the ecological balance of the biosphere.
Origin: first highlighted at the Stockholm Conference on the Human Environment, 1972. The Brundtland Commission report Our Common Future (1987) gave the definition above.
Sustainability vs development: sustainability protects long-term ecological balance, development improves quality of life, and sustainable development joins the two.
Broad requirements
Joint conservation and development
Basic needs met: food, shelter, water, health
Social justice and equity
Cultural diversity and self-determination
Ecological integrity
Essential conditions
Human demand stays within the carrying capacity of the environment
Resources conserved for future generations and other species
Poverty reduced and resources shared fairly
Participation of indigenous communities, women and tribals
Waste and pollution controlled, clean and renewable energy
Marine life protected, disaster resilience, hazardous material control
Investment in health and education
International efforts linking sustainable development and environment
| Effort | Year | What it did |
|---|---|---|
| Stockholm Conference | 1972 | Put the human environment on the global agenda |
| Convention on Biological Diversity | 1992 to 1994 | National strategies, awareness, protection of endangered species |
| UNFCCC | 1992 | Reporting of greenhouse gases, protect forests and carbon sinks |
| Forest Principles | 1992 | Sustainable forest management |
| Rio Declaration | 1992 | Right to a healthy environment, Polluter Pays principle |
| Agenda 21 | 1992 | Roughly 300-page action plan: land, water, air, poverty, health, education, sustainable consumption |
| World Summit on Sustainable Development | 2002, Johannesburg | Strengthened the Rio principles |
| UN Climate Change Conference | 2005, Montreal | Five-year programme on climate impacts |
"Sustainability creates and maintains conditions under which humans and nature can exist in productive harmony, fulfilling the social, economic and environmental needs of present and future generations."
Four principles taken from nature: solar energy, population control (within carrying capacity), nutrient recycling, biodiversity.
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| Pillar | Aim | Examples |
|---|---|---|
| Economic | Long-term growth without harming the environment | Employment, income stability, poverty reduction |
| Social | Social well-being and harmony | Justice, education, health, participation |
| Environmental | Live within natural limits | Conserve air, water, soil, biodiversity. Control pollution |
Exam tipCulture is sometimes added as a fourth pillar because it shapes values and practice. One line on this earns the extra mark.
Indicators of sustainability (11)
| Indicator | Why it matters |
|---|---|
| GDP growth | Growth can reduce poverty and environmental stress |
| Population stability | Stops over-exploitation |
| Water use | Clean water for drinking, farming, industry |
| Clean air index | Measures air quality |
| Human resource development | Education, health, nutrition, living standards |
| Energy intensity | Renewable use, below regeneration rate |
| Soil degradation | Erosion threatens agriculture |
| Forest coverage ratio | Forests regulate climate and water |
| Resource and material intensity | Efficient use and recycling |
| Transport energy use | Fossil fuel and pollution load |
| Recycling proportion | Conserves resources, cuts waste |