Climate Change – Causes, Effects and Mitigation (UPSC Prelims + Mains)
In many parts of India, people now feel that seasons are "not behaving normally" — longer heat waves, sudden very heavy rain in short time, unseasonal winter warmth, and stronger cyclones on the coast. These are not just random events. They are connected to a bigger long-term change in Earth's climate system. For UPSC, climate change is not only an Environment topic. It is linked with economy, agriculture, disaster management, health, energy security, international relations, internal security, and ethics (climate justice).
Climate Change
A long-term shift in average weather patterns (temperature, rainfall, wind, etc.) over decades or longer. Today, the main driver is human activity that increases greenhouse gases in the atmosphere.
Global Warming
The long-term rise in Earth's average surface temperature due mainly to the enhanced greenhouse effect caused by human emissions of greenhouse gases.
1) Why Climate Change is a High-Value UPSC Topic
- Prelims: Definitions, greenhouse gases, international agreements, institutions, India's missions and schemes, carbon markets, adaptation terms.
- Mains: Causes–effects–solutions, India's vulnerabilities, sector-wise mitigation, climate finance, technology transfer, climate justice, disaster risk reduction, policy design.
- Interview: Balanced answers: development needs + environment protection, equity + responsibility, practical local solutions.
2) Weather vs Climate: The Basic Clarity
Many students confuse weather with climate. UPSC expects clear conceptual answers.
Weather
Short-term atmospheric conditions at a place (today's temperature, today's rain, today's wind).
Climate
The long-term average pattern of weather of a region, usually measured over 30 years or more.
Simple example: A single hot day in Delhi is "weather". The trend that Delhi summers are becoming hotter and heat waves are longer is "climate change".
3) The Science in Simple Words: Greenhouse Effect
Earth receives energy from the Sun. Some energy is reflected back to space (because of clouds, ice, and bright surfaces). The rest warms the Earth. Earth also sends heat back towards space as infrared radiation.
Greenhouse Effect
A natural process where certain gases in the atmosphere trap some outgoing heat, keeping Earth warm enough for life. Without it, Earth would be too cold.
Then what is the problem? Human activities add extra greenhouse gases. This strengthens the greenhouse effect and traps more heat than normal. That is why Earth warms.
Enhanced Greenhouse Effect
The additional warming caused by human-made increase in greenhouse gases like carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).
4) Causes of Climate Change
4.1 Natural causes (limited role in current warming)
- Volcanic eruptions: Can cool the climate temporarily by sending particles into the atmosphere.
- Solar variation: Small changes in the Sun's energy output.
- Earth's orbital changes: Very long-term cycles (thousands of years).
These natural factors exist, but they do not explain the rapid warming trend seen in the last century. The dominant reason is human activity.
4.2 Human causes (main driver today)
- Burning fossil fuels: Coal, oil, and gas used for electricity, transport, and industry release large amounts of CO₂.
- Deforestation and land-use change: Cutting forests reduces carbon absorption and also releases stored carbon.
- Agriculture: Methane from cattle and rice fields; nitrous oxide from fertilisers.
- Industrial processes: Cement production releases CO₂; some industries release high-impact fluorinated gases.
- Waste: Landfills release methane; open burning of waste adds greenhouse gases and air pollutants.
4.3 Greenhouse gases: what UPSC must remember
| Greenhouse Gas | Main Human Sources | Why Important |
|---|---|---|
| CO₂ | Fossil fuels, cement, deforestation | Largest share of human-caused warming; stays long in atmosphere |
| CH₄ (Methane) | Livestock, rice fields, landfills, oil & gas leaks | Stronger warming effect than CO₂ over short time; key for near-term warming control |
| N₂O | Fertilisers, manure, some industrial processes | Long-lived; high warming impact |
| F-gases | Refrigeration, air conditioners, industrial use | Very high warming potential though smaller quantity |
Carbon Sink
A system that absorbs more carbon than it releases, like forests, soils, and oceans.
5) Effects of Climate Change (Global)
Climate change affects natural systems and human systems together. UPSC answers must show this interlinkage.
5.1 Temperature-related impacts
- More frequent heat waves and higher heat stress.
- Higher electricity demand for cooling, increasing pressure on power systems.
- Increased risk of wildfires in dry regions.
5.2 Water and rainfall impacts
- Irregular rainfall: Longer dry spells + short intense rain events.
- Droughts: Lower soil moisture and reduced water availability in many places.
- Floods: Urban flooding increases when heavy rain falls quickly and drainage is poor.
5.3 Oceans and coastal impacts
- Sea level rise: Due to melting ice and expansion of warm ocean water.
- Stronger storm surges: Bigger damage in coastal areas during cyclones.
- Ocean warming and acidification: Harms coral reefs and marine life.
5.4 Food, health, and economy impacts
- Agriculture: Heat stress reduces yields; pests and diseases expand to new areas; rainfall uncertainty increases crop risk.
- Health: Heat stroke, dehydration, spread of vector-borne diseases (like malaria/dengue in new zones), and worsening air quality.
- Economy: Infrastructure damage, productivity loss due to heat, higher insurance costs, and migration pressures.
Loss and Damage
Harm from climate change that cannot be avoided by mitigation or adaptation (for example, permanent loss of land due to sea-level rise, or irreversible ecosystem loss).
6) Climate Change Impacts in India (UPSC Mains Core)
India is highly vulnerable because of its long coastline, dependence on monsoon agriculture, large population, and many climate-sensitive livelihoods.
6.1 Monsoon and agriculture
- Monsoon uncertainty: Delayed onset, early withdrawal, or uneven distribution can affect sowing and irrigation planning.
- Extreme rain spells: A season can show overall normal rainfall, but with damaging bursts in short periods causing floods and crop loss.
- Heat impact on wheat and pulses: Higher temperatures during grain-filling stage can reduce yields and quality.
6.2 Heat waves and urban heat
- Heat waves: More days of extreme heat can reduce outdoor work capacity (construction, agriculture, informal sector).
- Urban Heat Island: Cities become hotter because of concrete surfaces, low greenery, and trapped heat.
Urban Heat Island
A situation where cities are significantly warmer than nearby rural areas due to buildings, roads, less vegetation, and waste heat from vehicles and ACs.
6.3 Himalayas and glaciers
- Glacier retreat: Threatens long-term water security of rivers fed by snow and ice.
- Higher disaster risk: Glacial lakes can burst (GLOF), causing sudden floods in mountain valleys.
GLOF (Glacial Lake Outburst Flood)
A sudden flood caused when a glacial lake's natural dam breaks, releasing large volumes of water and debris downstream.
6.4 Coasts and cyclones
- Sea level rise: Saltwater intrusion can harm farming and drinking water in coastal districts.
- Coastal erosion: Loss of land and damage to housing and roads.
- Stronger cyclones: Warmer seas can increase cyclone intensity, raising risk in Bay of Bengal and Arabian Sea coasts.
6.5 Biodiversity and ecosystems
- Coral reefs: Warming causes coral bleaching.
- Mangroves: Vital for coastal protection; stressed by sea-level rise and development pressure.
- Forests: Higher fire risk and shifting species distribution.
7) Key Concepts UPSC Expects You to Use
Mitigation
Actions that reduce the causes of climate change, mainly by cutting greenhouse gas emissions or increasing carbon sinks.
Adaptation
Adjustments in human or natural systems to reduce harm from climate impacts (for example, drought-resistant crops, flood-resilient infrastructure).
Resilience
The ability of a system (community, city, ecosystem) to absorb shocks (like floods or heat waves), recover quickly, and continue functioning.
CBDR-RC
Common But Differentiated Responsibilities and Respective Capabilities — all countries must act on climate change, but developed countries should take the lead because they contributed more historically and have greater capacity.
Net Zero
A stage where total greenhouse gases added to the atmosphere are balanced by removal (through sinks or technology). Net zero does not mean "zero emissions"; it means "net emissions become zero".
Carbon Budget
The total amount of CO₂ that can still be emitted while keeping global warming below a chosen temperature limit.
8) Global Response and Institutions (Prelims + Mains)
8.1 UN climate negotiations
- UNFCCC: The core global framework for climate cooperation.
- COP: Annual conference where member countries take decisions, review progress, and negotiate new steps.
- Kyoto Protocol: Earlier framework with binding targets mainly for developed countries.
- Paris Agreement: Current main agreement where all countries submit climate plans and improve them over time.
8.2 IPCC (science-policy bridge)
The IPCC does not make laws. It assesses scientific evidence and provides reports that guide policies globally.
IPCC
The Intergovernmental Panel on Climate Change is the global body that assesses climate science, impacts, and mitigation pathways through assessment reports.
8.3 New focus areas in climate talks
- Climate finance: Money support for mitigation and adaptation in developing countries.
- Loss and Damage: Support for unavoidable climate harms faced by vulnerable countries.
- Global Stocktake: Periodic check of collective progress under the Paris Agreement.
9) India's Climate Policy Framework
9.1 India's overall approach
India's approach is based on balancing development needs (energy access, jobs, poverty reduction) with climate action. India pushes for equity and climate justice while expanding renewable energy and efficiency.
9.2 National Action Plan on Climate Change (NAPCC)
NAPCC is India's broad umbrella plan. Its missions are important for Prelims and for Mains examples.
| Mission | Main Focus | Simple Example |
|---|---|---|
| National Solar Mission | Expand solar energy | Solar parks, rooftop solar |
| National Mission for Enhanced Energy Efficiency | Use less energy for same output | Efficient appliances, industrial efficiency |
| National Mission on Sustainable Habitat | Green buildings, urban planning | Better public transport, waste management |
| National Water Mission | Water conservation and efficiency | Micro-irrigation, rainwater harvesting |
| National Mission for Sustaining the Himalayan Ecosystem | Protect Himalayan ecology | Glacier monitoring, ecosystem studies |
| Green India Mission | Increase forest cover and quality | Afforestation, restoration |
| National Mission for Sustainable Agriculture | Climate-resilient farming | Drought-resistant crops, better irrigation |
| National Mission on Strategic Knowledge for Climate Change | Research and capacity building | Climate science, modelling, training |
9.3 India's NDC and long-term strategy (answer enrichment)
- NDC: India's national climate targets and actions submitted under the Paris framework.
- Long-Term Strategy (LT-LEDS): India's longer path for low-carbon development.
NDC (Nationally Determined Contribution)
A country's climate plan under the Paris Agreement, including mitigation targets and adaptation actions, updated over time.
9.4 Mission LiFE (behaviour change angle)
Many solutions are not only about technology. They are also about lifestyle and consumption patterns.
LiFE (Lifestyle for Environment)
A mass movement idea that encourages mindful consumption and sustainable lifestyle choices to reduce environmental harm.
10) Mitigation: How to Reduce Emissions (Sector-wise, UPSC-ready)
Mitigation works best when it is planned sector-wise. In Mains, write solutions under headings like energy, transport, industry, agriculture, forests, and waste.
10.1 Power and energy
- Renewable energy expansion: Solar, wind, small hydro, biomass, and clean grids.
- Energy storage: Batteries and pumped storage help manage renewable variability.
- Energy efficiency: LED bulbs, efficient fans, efficient pumps, star-rated appliances.
- Clean cooking: Reduces biomass burning and improves health, also reduces black carbon.
10.2 Transport
- Public transport: Metro, buses, last-mile connectivity.
- Electric mobility: EVs for two-wheelers, buses, and urban fleets.
- Fuel efficiency standards: Better engines, maintenance.
- Modal shift: More railways for freight, less road dependency.
10.3 Industry
- Energy-efficient production: Especially steel, cement, chemicals.
- Cleaner fuels: Natural gas where feasible, green hydrogen in the long run.
- Circular economy: Reuse, recycle, reduce material demand (less emissions).
Green Hydrogen
Hydrogen produced using renewable electricity (like solar or wind) through electrolysis, with very low or no carbon emissions.
10.4 Agriculture and livestock
- Better fertiliser use: Balanced nutrient use reduces nitrous oxide emissions.
- Rice cultivation methods: Water management can reduce methane.
- Livestock management: Better feed and manure management reduce methane.
- Climate-smart farming: Mixed cropping, agroforestry, micro-irrigation.
10.5 Forests and land
- Afforestation and reforestation: Increase carbon sinks.
- Prevent forest fires: Community-based fire management.
- Restore degraded lands: Improves soil carbon and livelihoods.
- Mangroves: High carbon storage and strong coastal protection.
10.6 Waste management
- Segregation at source: Wet and dry waste separation reduces landfill methane.
- Composting and biogas: Convert organic waste into useful products.
- Landfill gas capture: Methane can be captured and used as energy.
- Reduce open burning: Improves air quality and reduces emissions.
10.7 Carbon markets and pricing (new UPSC trend)
India is working on domestic carbon markets. These policies aim to reward lower emissions and improve efficiency.
Carbon Market
A system where carbon credits (representing emission reductions) can be traded, creating a financial incentive to cut emissions.
Carbon Credit
A certificate representing reduction or removal of greenhouse gases, used for trading or compliance depending on the system design.
11) Adaptation: Living with Some Climate Impacts
Even if the world cuts emissions, some warming and impacts are already "locked in". Adaptation is essential, especially for India.
11.1 Agriculture adaptation
- Climate-resilient crops: Drought-tolerant and heat-tolerant varieties.
- Micro-irrigation: Drip and sprinkler systems improve water efficiency.
- Weather advisories: Better local forecasts for farmers.
- Crop diversification: Reduces risk from single-crop failure.
11.2 Water adaptation
- Watershed management: Check dams, contour bunding, soil moisture conservation.
- Groundwater governance: Community management and recharge.
- Urban water planning: Protect lakes and wetlands that store water naturally.
11.3 Disaster risk reduction
- Early warning systems: Cyclone warnings and evacuation reduce deaths greatly.
- Climate-resilient infrastructure: Stronger embankments, stormwater drains, safer housing.
- Heat Action Plans: Cool roofs, public water points, timing changes for outdoor work.
11.4 Urban adaptation
- More urban greenery: Parks, roadside trees, urban forests reduce heat.
- Cool roofs and reflective surfaces: Lower indoor temperatures.
- Better drainage: Prevent urban flooding during intense rainfall.
12) Challenges and Debates (Write Balanced Answers)
- Development vs emissions: India needs energy for growth, but the energy must become cleaner.
- Climate justice: Those who contributed least often suffer most.
- Finance gap: Clean transition requires huge investment and affordable technology.
- Just transition: Workers and regions dependent on coal need alternative jobs and skills.
- Policy implementation: Good plans fail if governance, data, and coordination are weak.
Just Transition
A transition to a low-carbon economy that is fair and inclusive, protecting workers and communities dependent on high-carbon sectors (like coal) through reskilling and alternative livelihoods.
13) Way Forward: UPSC Mains-Style Conclusion
- Combine mitigation + adaptation: Both are necessary; India cannot choose only one.
- Accelerate clean energy with reliability: Renewables plus storage, stronger grids, and efficiency.
- Nature-based solutions: Restore forests, wetlands, and mangroves for carbon and resilience.
- Climate-resilient agriculture: Water-efficient farming, local advisories, risk insurance, and diversification.
- Finance and technology: Better access to climate finance, and faster adoption of clean technologies.
- Local governance: Panchayats and urban local bodies must be empowered for climate action.
- People's movement: Behaviour change (saving energy, reducing waste) strengthens policy outcomes.
One-line UPSC-ready ending: Climate change is a development challenge and an opportunity — if India builds a low-carbon, climate-resilient economy, it can protect lives today while securing growth for tomorrow.
PYQs (Previous Year Questions) – With Answers
PYQ 1: Explain the difference between mitigation and adaptation in climate change. Give examples from India.
Answer (key points):
- Mitigation: Reduce emissions / increase sinks (solar energy expansion, energy efficiency, afforestation).
- Adaptation: Reduce harm from impacts (Heat Action Plans, drought-resistant crops, flood-resilient infrastructure).
- Indian examples: Renewable energy and efficiency are mitigation; cyclone early warning and resilient housing are adaptation.
PYQ 2: Discuss the impact of climate change on Indian agriculture and food security.
Answer (key points):
- Monsoon variability affects sowing and yields.
- Heat stress reduces productivity and increases irrigation demand.
- More pest and disease attacks; higher risk of crop losses from floods/droughts.
- Solutions: climate-resilient seeds, micro-irrigation, advisories, diversification, storage and supply chain improvements.
PYQ 3: What is climate justice? Explain CBDR-RC and its importance for India.
Answer (key points):
- Climate justice: Fair sharing of burdens and benefits of climate action, considering historical responsibility and vulnerability.
- CBDR-RC: Common responsibility for all, but differentiated duties based on past emissions and capacity.
- India's position: Developed nations must lead in deep cuts and finance/technology support; developing nations need space for poverty reduction with cleaner pathways.
PYQ 4: How can urban planning help India deal with climate change?
Answer (key points):
- Reduce emissions through public transport, walkability, EV infrastructure.
- Improve resilience via drainage, floodplain protection, and wetlands conservation.
- Reduce heat through urban green cover, cool roofs, and better building design.
- Strengthen waste management to reduce methane and pollution.
Practice MCQs (Prelims) – With Answers and Explanations
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Which of the following is the best description of "Climate"?
- (a) Daily temperature changes
- (b) Weekly rainfall pattern
- (c) Long-term average weather pattern of a region
- (d) Short-term wind speed variation
Answer: (c) Explanation: Climate is measured over long periods (often 30 years+), not daily/weekly changes.
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Which gas is most closely linked with emissions from rice fields and ruminant animals?
- (a) Carbon dioxide
- (b) Methane
- (c) Nitrous oxide
- (d) Ozone
Answer: (b) Explanation: Anaerobic conditions in rice paddies and digestion in cattle produce methane.
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"Urban Heat Island" mainly occurs due to:
- (a) More lakes in cities
- (b) Higher forest cover in cities
- (c) Concrete surfaces, less greenery, and trapped heat
- (d) Lower population density
Answer: (c) Explanation: Built-up surfaces absorb and re-radiate heat; less vegetation reduces cooling.
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Which of the following is an example of "Adaptation"?
- (a) Installing solar panels
- (b) Planting trees to increase carbon sink
- (c) Building cyclone shelters and improving early warning
- (d) Improving fuel efficiency standards
Answer: (c) Explanation: Cyclone shelters and early warning reduce harm from climate impacts (adaptation).
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CBDR-RC is mainly associated with:
- (a) Wildlife protection
- (b) Climate negotiations and equity principle
- (c) Nuclear disarmament
- (d) Ocean shipping rules
Answer: (b) Explanation: CBDR-RC is a core equity principle in global climate governance.
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Which of the following is a "carbon sink"?
- (a) Coal-based thermal plant
- (b) Cement factory
- (c) Mangrove forest
- (d) Oil refinery
Answer: (c) Explanation: Forest ecosystems absorb carbon; mangroves are strong carbon sinks.
-
Glacial Lake Outburst Flood (GLOF) is most likely in:
- (a) Coastal plains
- (b) Desert dunes
- (c) Himalayan valleys with glacial lakes
- (d) Deep ocean trenches
Answer: (c) Explanation: GLOF occurs when a glacial lake dam breaks in mountain regions.
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Which sector is a major source of nitrous oxide (N₂O) emissions?
- (a) Fertiliser use in agriculture
- (b) Wind energy
- (c) Hydropower
- (d) Solar rooftops
Answer: (a) Explanation: Nitrous oxide is strongly linked with nitrogen fertilisers and manure management.
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The main purpose of a carbon market is to:
- (a) Increase fossil fuel consumption
- (b) Provide financial incentive to reduce emissions
- (c) Ban all industrial activity
- (d) Promote only nuclear power
Answer: (b) Explanation: Carbon markets create a price signal for emissions reduction.
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Which of the following is the best statement about "Net Zero"?
- (a) It means no emissions at all
- (b) It means emissions equal removals overall
- (c) It is only about tree planting
- (d) It applies only to developed countries
Answer: (b) Explanation: Net zero means balancing emissions with removals, not absolute zero emissions.