🌡️ Chapter 06 · Topic 06 · Climate Change
Climate Change — Complete Revision
All key facts, dates, numbers, and concepts from Chapter 06 — greenhouse effect, ozone depletion, El Niño, IPCC, Paris Agreement, India’s commitments — in one quick-revision page.
⚡ Quick-Fire Key Facts
| Topic | Key Fact |
|---|---|
| Natural greenhouse effect | Keeps Earth at +15°C; without it = −18°C |
| CO₂ pre-industrial | ~280 ppm → current ~420 ppm (50% increase) |
| CO₂ GWP | 1 (reference); CH₄ = 27–30; N₂O = 273; SF₆ = 23,500 |
| Current warming | ~1.1°C above pre-industrial (IPCC AR6, 2021) |
| Paris Agreement target | Well below 2°C; aim for 1.5°C |
| Ozone layer altitude | 15–35 km (stratosphere); peak at ~25 km |
| Ozone hole definition | <220 Dobson Units (DU); normal ~300 DU |
| Ozone hole discovery | 1985, British Antarctic Survey (Farman et al.) |
| Montreal Protocol | 1987; 197 parties; only UN treaty with universal ratification |
| Kigali Amendment | 2016; phase-down of HFCs; India ratified 2021 |
| El Niño effect on India | Weakens monsoon → drought risk |
| La Niña effect on India | Strengthens monsoon → above-normal rainfall |
| Positive IOD effect | Good monsoon for India |
| IPCC established | 1988; UNEP + WMO; Geneva; Nobel Peace Prize 2007 |
| Paris Agreement adopted | COP21, December 2015; entered into force 4 Nov 2016 |
| India’s net zero target | 2070 (announced COP26, Glasgow) |
| India’s renewable target | 500 GW by 2030 |
| Green Climate Fund HQ | Incheon, South Korea |
| UNFCCC secretariat | Bonn, Germany |
| Loss & Damage Fund | Established COP27, Sharm el-Sheikh, 2022 |
🧪 Greenhouse Gases — Quick Comparison
| Gas | GWP (100-yr) | Main Source | Note |
|---|---|---|---|
| CO₂ | 1 | Fossil fuels, deforestation | Most abundant anthropogenic GHG |
| CH₄ | 27–30 | Livestock, rice, landfills | 80× CO₂ over 20 years |
| N₂O | 273 | Fertilisers, livestock | Also destroys ozone |
| HFCs | Hundreds–thousands | Refrigerants (replaced CFCs) | Zero ODP; Kigali Amendment targets |
| CFCs | Up to 10,900 | Old refrigerants (banned) | Also destroy ozone; ODP up to 1.0 |
| SF₆ | 23,500 | Electrical switchgear | Highest GWP; very long-lived |
| Water vapour | N/A | Evaporation (natural) | Most abundant GHG; feedback gas |
🕳️ Ozone Depletion — Key Points
- Stratospheric ozone = beneficial (absorbs UV-B, UV-C); tropospheric ozone = harmful (air pollutant)
- CFCs = most important ODS; halons = highest ODP per molecule (3–10)
- 1 Cl atom from CFC destroys 100,000 ozone molecules (catalytic reaction)
- Antarctic ozone hole = polar vortex + polar stratospheric clouds (PSCs) + spring sunlight
- Vienna Convention (1985) = framework; Montreal Protocol (1987) = binding phase-out
- Ozone recovery: mid-latitudes ~2040; Arctic ~2045; Antarctica ~2066
- Nobel Prize Chemistry 1995 = Molina, Rowland, Crutzen
🌊 ENSO & IOD — Key Points
- Walker Circulation = normal trade winds blow west; warm western Pacific drives Indian monsoon
- El Niño = trade winds weaken = eastern Pacific warms = Indian monsoon weakens
- La Niña = trade winds strengthen = western Pacific warms = Indian monsoon strengthens
- SOI = Southern Oscillation Index; negative = El Niño; positive = La Niña
- ENSO cycles every 2–7 years
- Positive IOD = western Indian Ocean warmer = good monsoon for India
- IOD can counteract ENSO effects (e.g., 2019: El Niño + positive IOD = normal monsoon)
- MJO = 30–60 day intra-seasonal variability; affects monsoon active/break spells
🌍 Climate Agreements — Timeline
| Year | Event | Key Point |
|---|---|---|
| 1988 | IPCC established | UNEP + WMO; Geneva |
| 1992 | UNFCCC adopted (Rio) | Framework; CBDR principle; 197 parties |
| 1997 | Kyoto Protocol (COP3) | Binding targets for developed countries; CDM |
| 2005 | Kyoto Protocol in force | First commitment period 2008–2012 |
| 2007 | IPCC AR4; Nobel Prize | Warming “unequivocal”; IPCC + Al Gore |
| 2009 | Copenhagen Accord (COP15) | Non-binding; 2°C target; $100 bn pledge |
| 2015 | Paris Agreement (COP21) | 1.5°C/2°C target; NDCs; all countries |
| 2016 | Kigali Amendment | Phase-down HFCs; India ratified 2021 |
| 2021 | COP26 Glasgow | India’s Panchamrit; coal phase-down |
| 2022 | COP27 Sharm el-Sheikh | Loss & Damage Fund established |
| 2023 | COP28 Dubai | First Global Stocktake; transition from fossil fuels |
🇮🇳 India’s Climate Commitments — Summary
India’s Panchamrit (COP26, 2021):
1️⃣ 500 GW non-fossil fuel electricity capacity by 2030
2️⃣ 50% electricity from non-fossil fuel sources by 2030
3️⃣ Reduce emissions intensity of GDP by 45% by 2030 (from 2005 levels)
4️⃣ Create additional carbon sink of 2.5–3 billion tonnes CO₂e through forests by 2030
5️⃣ Achieve net zero emissions by 2070
1️⃣ 500 GW non-fossil fuel electricity capacity by 2030
2️⃣ 50% electricity from non-fossil fuel sources by 2030
3️⃣ Reduce emissions intensity of GDP by 45% by 2030 (from 2005 levels)
4️⃣ Create additional carbon sink of 2.5–3 billion tonnes CO₂e through forests by 2030
5️⃣ Achieve net zero emissions by 2070
✅ Master Revision Checklist — Chapter 06
✅ Natural GHE = +15°C; enhanced GHE = human-caused = global warming
✅ CO₂ = GWP 1; CH₄ = 27–30; N₂O = 273; SF₆ = 23,500 (highest GWP)
✅ CO₂ = 280 ppm (pre-industrial) → 420 ppm (current) = 50% increase
✅ Current warming = 1.1°C above pre-industrial (IPCC AR6)
✅ Ice-albedo feedback = positive; water vapour feedback = strongest positive
✅ Ozone layer = stratosphere = 15–35 km = absorbs UV-B and UV-C
✅ Dobson Units = measure ozone; normal ~300 DU; hole <220 DU
✅ CFCs = main ODS; 1 Cl atom destroys 100,000 O₃ molecules
✅ Halons = highest ODP (3–10); used in fire extinguishers
✅ Antarctic ozone hole = 1985 discovery = forms Sep–Nov (spring)
✅ Polar vortex + PSCs = conditions for Antarctic ozone hole
✅ Vienna Convention (1985) = framework; Montreal Protocol (1987) = binding
✅ Montreal Protocol = 197 parties = only UN treaty with universal ratification
✅ Kigali Amendment (2016) = phase-down HFCs = 0.5°C warming prevented
✅ India ratified Kigali Amendment 2021; HFC phase-down 85% by 2047
✅ Ozone recovery: Antarctica ~2066; Arctic ~2045; mid-latitudes ~2040
✅ Nobel Chemistry 1995 = Molina, Rowland, Crutzen
✅ El Niño = trade winds weaken = eastern Pacific warms = weak Indian monsoon
✅ La Niña = trade winds strengthen = strong Indian monsoon
✅ SOI negative = El Niño; SOI positive = La Niña
✅ Positive IOD = good monsoon for India; negative IOD = poor monsoon
✅ MJO = 30–60 day cycle = affects monsoon active/break spells
✅ IPCC = 1988 = UNEP + WMO = Geneva = Nobel Peace Prize 2007
✅ IPCC AR6 (2021–22) = “unequivocal” human cause = 1.5°C by early 2030s
✅ UNFCCC = 1992, Rio = Bonn secretariat = CBDR principle
✅ Kyoto Protocol = 1997 = binding targets for developed countries = CDM
✅ Paris Agreement = COP21, 2015 = well below 2°C; aim 1.5°C = all countries
✅ NDCs = updated every 5 years = ratchet mechanism
✅ India’s Panchamrit = 500 GW; 50% non-fossil; 45% intensity; net zero 2070
✅ International Solar Alliance = India + France = COP21 = 120+ members
✅ Green Climate Fund = Incheon, South Korea
✅ Loss & Damage Fund = COP27, 2022; operationalised COP28, 2023
✅ COP28 Dubai (2023) = First Global Stocktake = transition from fossil fuels
✅ CO₂ = GWP 1; CH₄ = 27–30; N₂O = 273; SF₆ = 23,500 (highest GWP)
✅ CO₂ = 280 ppm (pre-industrial) → 420 ppm (current) = 50% increase
✅ Current warming = 1.1°C above pre-industrial (IPCC AR6)
✅ Ice-albedo feedback = positive; water vapour feedback = strongest positive
✅ Ozone layer = stratosphere = 15–35 km = absorbs UV-B and UV-C
✅ Dobson Units = measure ozone; normal ~300 DU; hole <220 DU
✅ CFCs = main ODS; 1 Cl atom destroys 100,000 O₃ molecules
✅ Halons = highest ODP (3–10); used in fire extinguishers
✅ Antarctic ozone hole = 1985 discovery = forms Sep–Nov (spring)
✅ Polar vortex + PSCs = conditions for Antarctic ozone hole
✅ Vienna Convention (1985) = framework; Montreal Protocol (1987) = binding
✅ Montreal Protocol = 197 parties = only UN treaty with universal ratification
✅ Kigali Amendment (2016) = phase-down HFCs = 0.5°C warming prevented
✅ India ratified Kigali Amendment 2021; HFC phase-down 85% by 2047
✅ Ozone recovery: Antarctica ~2066; Arctic ~2045; mid-latitudes ~2040
✅ Nobel Chemistry 1995 = Molina, Rowland, Crutzen
✅ El Niño = trade winds weaken = eastern Pacific warms = weak Indian monsoon
✅ La Niña = trade winds strengthen = strong Indian monsoon
✅ SOI negative = El Niño; SOI positive = La Niña
✅ Positive IOD = good monsoon for India; negative IOD = poor monsoon
✅ MJO = 30–60 day cycle = affects monsoon active/break spells
✅ IPCC = 1988 = UNEP + WMO = Geneva = Nobel Peace Prize 2007
✅ IPCC AR6 (2021–22) = “unequivocal” human cause = 1.5°C by early 2030s
✅ UNFCCC = 1992, Rio = Bonn secretariat = CBDR principle
✅ Kyoto Protocol = 1997 = binding targets for developed countries = CDM
✅ Paris Agreement = COP21, 2015 = well below 2°C; aim 1.5°C = all countries
✅ NDCs = updated every 5 years = ratchet mechanism
✅ India’s Panchamrit = 500 GW; 50% non-fossil; 45% intensity; net zero 2070
✅ International Solar Alliance = India + France = COP21 = 120+ members
✅ Green Climate Fund = Incheon, South Korea
✅ Loss & Damage Fund = COP27, 2022; operationalised COP28, 2023
✅ COP28 Dubai (2023) = First Global Stocktake = transition from fossil fuels