Climate Change & Global Warming
The greenhouse effect, the main greenhouse gases and their warming potential, the causes and impacts of global warming, and key concepts like net-zero.
Key Takeaways
- The greenhouse effect is natural; human emissions have enhanced it, causing global warming.
- Carbon dioxide is the main greenhouse gas by volume; methane has a much higher warming potential per molecule.
- Impacts include sea-level rise, extreme weather, glacier melt and ocean acidification.
Core concept
The greenhouse effect is a natural process: greenhouse gases (GHGs) in the atmosphere absorb outgoing infrared (heat) radiation and keep the Earth warm enough for life. Global warming occurs when human emissions raise GHG levels, trapping extra heat — the enhanced greenhouse effect — driving climate change.
Static foundation — the greenhouse gases
- Carbon dioxide (CO₂): the largest contributor by volume (fossil fuels, deforestation).
- Methane (CH₄): from paddy fields, livestock, landfills — a much stronger warmer per molecule.
- Nitrous oxide (N₂O): from fertilisers.
- Others: CFCs/HFCs, water vapour, ozone.
Greenhouse Gases & Their Sources
| Gas | Main sources | Relative warming (GWP) |
|---|---|---|
| Carbon dioxide (CO₂) | Fossil fuels, deforestation, cement | Baseline (1) |
| Methane (CH₄) | Paddy, livestock, landfills, oil & gas | ~25–28× over 100 years |
| Nitrous oxide (N₂O) | Nitrogen fertilisers, industry | ~265–298× |
| Fluorinated gases (HFCs) | Refrigeration, air-conditioning | Very high (thousands×) |
Key Climate Concepts
Tap to reveal.
Impacts of global warming
Rising temperatures cause sea-level rise (thermal expansion + melting ice), glacier retreat (threatening Himalayan rivers), more frequent extreme weather (heatwaves, floods, cyclones), monsoon disruption, ocean acidification and coral bleaching, and biodiversity loss. India is highly vulnerable due to its long coastline, monsoon dependence and large agrarian population.
Current affairs linkage
The IPCC assessment reports warn that limiting warming to 1.5°C needs deep, rapid cuts. India's response — the Panchamrit pledges, the National Action Plan on Climate Change (8 missions), and Mission LiFE (Lifestyle for Environment). (Add the latest IPCC finding or India climate pledge.)
Prelims trap zones
- The greenhouse effect is natural and necessary; it's the ENHANCED effect (from human emissions) that is the problem.
- CO₂ is largest by VOLUME, but methane and N₂O have far higher warming potential per molecule.
- Water vapour is the most abundant greenhouse gas — but its level is driven by temperature (a feedback), not emitted directly.
Prelims Pointers
- Major greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), water vapour, CFCs, ozone.
- Global Warming Potential (GWP): methane is ~25–28× and nitrous oxide ~265–298× that of CO₂ over 100 years.
- A carbon sink (forest, ocean) absorbs more carbon than it releases.
- Net-zero means balancing emitted greenhouse gases with an equal amount removed.
Mains Angle
- 'India is both a victim of and a key player in the fight against climate change.' Discuss.
- Examine the impacts of climate change on Indian agriculture and the monsoon.
Practice this topic
Browse all Environment & Ecology MCQs →Ready for Mains? Write a full answer on this topic and get it graded by our AI examiner.
Write an answerRelated topics
Ecology & Ecosystems
The fundamentals of ecology — the levels of biological organisation, the abiotic and biotic components of an ecosystem, and its types and functions.
Food Chains, Energy Flow & Ecological Pyramids
How energy and matter move through an ecosystem — food chains and webs, trophic levels, the 10% law of energy transfer, and ecological pyramids.
Biogeochemical Cycles
How nutrients circulate through the living and non-living world — the carbon, nitrogen and phosphorus cycles, and the difference between gaseous and sedimentary cycles.
Biodiversity & Hotspots
The three levels of biodiversity, why it matters, the criteria for biodiversity hotspots, and India's four hotspots as a megadiverse nation.