Full Chapter Summary & Detailed Notes - World Climate and Climate Change Class 11 NCERT
Overview & Key Concepts
- Chapter Goal: Understand world climate classification, Koeppen's empirical scheme based on temperature and precipitation, major climate types and their characteristics, distribution, vegetation. Also, explore climate change causes, global warming, GHGs, impacts. Exam Focus: Koeppen groups (A B C D E), types (Af Am Aw BSh BWh etc.), climate change evidence, astronomical/terrestrial causes, Kyoto protocol. 2025 Updates: Emphasis on recent warming trends, IPCC reports integration. Fun Fact: Koeppen's scheme from 1918, modified till 1936, still widely used. Core Idea: Climate as synthesis of weather; empirical classification relates vegetation. Real-World: Monsoon impacts agriculture in India. Ties: To previous chapters on atmosphere, weather; next on water, soils. Expanded: Climate influences human activities, ecosystems; change poses threats like sea rise, extreme events.
- Wider Scope: Genetic vs empirical; applied for agriculture/urban planning. Variability past/present; anthropogenic warming.
- Expanded Content: Three approaches: Empirical (data-based temp/precip), genetic (causes like air masses), applied (specific purposes e.g. agriculture). Koeppen links vegetation distribution. Climate change: Geological evidence (glacials), recent extremes (1990s warmest). Causes: Sunspots, Milankovitch, volcanism, GHGs. Impacts: Sea level rise, biodiversity loss.
Introduction & Classification Approaches
World climate studied by organizing data into units for understanding. Three approaches: Empirical (observed temp/precip), genetic (causes), applied (specific purpose). Expanded: Empirical simplest, uses stats; genetic complex, air masses/fronts; applied e.g. building design, crop suitability. Koeppen's empirical most used, relates vegetation.
- Examples: Temp averages classify hot/cold; precip wet/dry.
- Point: Synthesis smaller units aids analysis/description.
- Expanded: Data from stations worldwide; climate averages weather over time (30 years).
Extended: Climate dynamic, influenced by latitude, altitude, ocean currents. Variations lead to diverse biomes, human adaptations.
Koeppen’s Scheme of Classification
V. Koeppen (1918, modified) empirical based mean annual/monthly temp/precip. Relates vegetation distribution. Capital letters groups: A tropical, B dry, C warm temperate, D cold snow forest, E cold. Small letters types: f no dry, m monsoon, w winter dry, s summer dry; a b c d temp severity. B subdivided S steppe, W desert; h hot, k cold. Expanded: Selected values e.g. A: coldest >18°C; B: evap>precip. Popular for simplicity, vegetation link.
- Examples: Af equatorial wet; BWh subtropical desert.
- Point: Five groups, four temp-based, one precip.
- Expanded: Table 11.1 groups characteristics; 11.2 types/codes.
Extended: Used globally; critiques: ignores winds, ignores extremes. Still in textbooks for education.
Group A: Tropical Humid Climates
Between Tropics; hot humid, low temp range, high rain. Types: Af wet (equator, Amazon/Africa/Indies; thunder showers, 30°C max/20°C min, evergreen forests); Am monsoon (India NE, S America NE, N Australia; summer rain, winter dry); Aw wet-dry (N/S Af, Amazon borders, Sudan; shorter wet, longer dry, deciduous/grasslands). Expanded: ITCZ overhead; biodiversity high in Af; monsoons from wind reversal.
- Examples: Amazon basin Af; Indian subcontinent Am.
- Point: Annual rain high, temp uniform.
- Expanded: Vegetation adapts: Dense canopy Af, shedding Aw.
Extended: Human impacts: Deforestation Am/Aw; agriculture suits wet seasons.
Dry Climates: B
Low rain, inadequate plants; 15-60° latitudes. Subsidence highs, cold currents extend equatorward. Types: BS steppe semi-arid, BW desert arid; subtropical (BSh/BWh 15-35°), mid-latitude (BSk/BWk 35-60°). Expanded: Variability high; thundershowers ineffective; fog coastal deserts. Temps extreme: 58°C Al Aziziyah. Sparse grass steppe, barren desert.
- Examples: Sahara BWh; Great Plains BSk.
- Point: Evap>precip; famine risks steppe.
- Expanded: Interiors/mountains block moisture; cold currents e.g. Peru.
Extended: Nomadic life deserts; irrigation oasis farming.
Warm Temperate (Mid-Latitude) Climates: C
30-50° margins; warm summers, mild winters. Types: Cwa subtropical humid winter dry (N India/China; warm winter); Cs Mediterranean (Med sea, California/Chile/Australia; hot dry summer, mild rainy winter, 25°C summer/10°C winter, 35-90cm rain); Cfa humid subtropical (E US/China/Japan/Argentina/Africa/Australia; rain year-round, 75-150cm, 27°C summer/5-12°C winter); Cfb marine west coast (NW Europe, N America, Chile/Australia/NZ; moderate, 15-20°C summer/4-10°C winter, 50-250cm rain). Expanded: Air masses unstable Cfa; westerlies winter Cs.
- Examples: California Cs; UK Cfb.
- Point: Eastern/western differences.
- Expanded: Vegetation: Evergreen Cs, deciduous Cfa.
Extended: Agriculture: Fruits Cs, mixed farming Cfb.
Cold Climates: D & E
D: 40-70°N continental (Europe/Asia/N America); Df humid winter (cold snowy, short frost-free, large ranges); Dw dry winter (NE Asia; monsoon reversal, very cold winter, 12-15cm rain). E: >70°; ET tundra (mosses/lichens, permafrost, long daylight summer); EF ice cap (Greenland/Antarctica; below freezing, little precip, icebergs). Expanded: Anticylone Dw; severity increases poleward D.
- Examples: Siberia Dw; Antarctica EF.
- Point: Harsh, limited life.
- Expanded: Taiga forests Df; no true summer ET.
Extended: Research stations EF; reindeer herding ET.
Climate Change & Global Warming
Past: 10,000 years stable with fluctuations; glacials/interglacials geological. Evidence: Geomorphology, sediments, tree rings, history. India: Wet 8000BC, Harappan 3000-1700BC, dry after. Recent: 1990s extremes, Sahel drought 1967-77, Dust Bowl 1930s, Little Ice Age 1550-1850, warming 1885-1940. Causes: Astronomical (sunspots cool/warm, Milankovitch orbital/tilt/wobble), terrestrial (volcanism aerosols, GHGs). Global warming: GHGs (CO2, CFCs, CH4, N2O, O3) trap heat; CO2 from fuels/deforestation; CFCs ozone hole. Kyoto 1997: Reduce 5% by 2012. Impacts: Uneven warming, sea rise, inundation. Expanded: 20th century +0.6°C; 1998 warmest. Efforts: Lifestyle changes for livable world.
- Examples: Pinatubo cooling; ozone Antarctica.
- Point: Anthropogenic dominant now.
- Expanded: Sinks forests/oceans; doubling CO2 index models.
Extended: Concerns: Biodiversity, social problems; hope community response.
Summary
- Classification Koeppen groups/types; climates tropical-dry-temperate-cold-polar; change natural/anthropogenic, warming GHGs.
Why This Guide Stands Out
Complete: All subtopics, examples, Q&A, quiz. Geography-focused. Free 2025. Expanded with real-world links, critiques.
Key Themes & Tips
- Aspects: Empirical, vegetation link, change causes/impacts.
- Thinkers: Koeppen, Milankovitch.
- Tip: Memorize codes/groups; causes debate; warming explain. Expanded: Compare climates India/world.
Exam Case Studies
Monsoon India, Sahara desert, global warming sea rise.
Project & Group Ideas
- Kyoto info collect.
- Debate GHGs reduction.
60+ Questions & Answers - NCERT Based (Class 11)
Part A (1 mark short), B (4 marks medium), C (8 marks long). Based on NCERT, exercises. Answer lengths: 1 mark ~2 lines, 4 marks ~5 lines, 8 marks ~10 lines. Expanded with more questions.
Part A: 1 Mark Questions
1. What is empirical classification based on?
1 Mark Answer: Observed data, particularly temperature and precipitation. It uses mean values for grouping.
2. Who developed Koeppen's scheme?
1 Mark Answer: V. Koeppen in 1918, modified over time. Empirical based on temp/precip vegetation.
3. What does 'A' group represent in Koeppen?
1 Mark Answer: Tropical humid; coldest month average ≥18°C. High rain, low temp range.
4. Define B dry climates.
1 Mark Answer: Potential evaporation exceeds precipitation. Includes steppes and deserts.
5. What is Af type?
1 Mark Answer: Tropical wet; no dry season, rain every month. Equatorial regions like Amazon.
6. What does 'f' indicate?
1 Mark Answer: No dry season; precipitation throughout year. Used in humid types.
7. Name a cause of climate change.
1 Mark Answer: Sunspot activities; increase leads to cooler weather. Astronomical factor.
8. What is GHGs?
1 Mark Answer: Greenhouse gases trap longwave radiation. Examples: CO2, CH4, CFCs.
9. Define tundra climate.
1 Mark Answer: ET; no true summer, permafrost, low vegetation. Poleward 70°.
10. What is Cs climate?
1 Mark Answer: Mediterranean; dry hot summer, mild rainy winter. 30-40° west coasts.
11. Name a GHG from human activity.
1 Mark Answer: CFCs; destroy ozone, from aerosols/refrigerants. High effectiveness.
12. What is Milankovitch theory?
1 Mark Answer: Orbital variations alter insolation. Includes tilt, wobble, eccentricity.
13. Define ice cap EF.
1 Mark Answer: Perennial ice, below freezing always. Greenland/Antarctica.
14. What is BWh?
1 Mark Answer: Subtropical desert; low-latitude arid. High temps, low rain.
15. Name evidence of past climate.
1 Mark Answer: Tree rings; indicate wet/dry periods. Historical records.
16. What is Kyoto protocol?
1 Mark Answer: 1997 agreement reduce GHGs 5% by 2012. 141 nations ratified.
17. Define global warming.
1 Mark Answer: Rise in earth temp from GHGs. +0.6°C 20th century.
18. What is Am climate?
1 Mark Answer: Tropical monsoon; short dry season. Heavy summer rain.
19. Name a polar climate type.
1 Mark Answer: EF ice cap; perennial ice, little precip.
20. What is ozone hole?
1 Mark Answer: Depletion over Antarctica from CFCs. Allows UV rays.
21. What is Cfb?
1 Mark Answer: Marine west coast; no dry, moderate temps. NW Europe.
22. Define volcanism cause.
1 Mark Answer: Aerosols reduce solar radiation, cooling. E.g. Pinatubo.
Part B: 4 Marks Questions
1. Explain three approaches to classifying climate.
4 Marks Answer: Empirical based on observed data like temp/precip for easy grouping. Genetic organizes by causes such as air masses/fronts. Applied for specific purposes e.g. agriculture/urban planning. Koeppen uses empirical relating vegetation. Expanded: Empirical simple stats; genetic explains dynamics; applied practical.
2. Describe Koeppen's climatic groups.
4 Marks Answer: Five groups: A tropical (coldest ≥18°C), B dry (evap>precip), C warm temperate (coldest -3 to 18°C), D cold snow forest (coldest ≤-3°C), E cold (all <10°C). A C D E humid, B dry. Expanded: Based temp except B precip; letters designate.
3. What is tropical wet climate Af?
4 Marks Answer: Near equator e.g. Amazon/Africa/Indies; rain every month thunder showers. Uniform high temp 30°C max/20°C min, low range. Evergreen forests dense canopy biodiversity. Expanded: Afternoon convection; no seasons.
4. Explain dry climates B characteristics.
4 Marks Answer: Low rain inadequate plants; 15-60° subsidence highs/cold currents. Variability high, thundershowers ineffective, fog coastal. Summer temps high e.g. 58°C Libya, large diurnal ranges. Expanded: Famine risks steppe; barren deserts.
5. Describe Mediterranean Cs.
4 Marks Answer: 30-40° west coasts e.g. California/Chile/Australia; hot dry summer subtropical high, mild rainy winter westerlies. Temps 25°C summer/<10°C winter, 35-90cm rain. Expanded: Evergreen veg; fruit cultivation.
6. What is tundra ET?
4 Marks Answer: Poleward 70°; permafrost subsoil frozen, short grow season water logging. Low plants mosses/lichens/flowers; long summer daylight. Expanded: No trees; fragile ecosystem.
7. Explain sunspot cause of change.
4 Marks Answer: Dark cooler patches cycle; increase cooler wetter storms, decrease warm drier. Astronomical; not statistically significant. Expanded: Linked solar output variations.
8. Describe greenhouse effect.
4 Marks Answer: Atmosphere transmits solar but absorbs longwave from earth. Gases trap heat like glasshouse. Analogy: Car warmer closed. Expanded: Natural; enhanced human GHGs.
9. What are GHGs?
4 Marks Answer: CO2 from fuels/deforestation, CFCs human, CH4 rice/livestock, N2O fertilizers, O3 troposphere. Effectiveness concentration/lifetime/wavelength. Expanded: CO2 20-50 years adjust.
10. Explain Kyoto protocol.
4 Marks Answer: 1997, effect 2005, 141 nations; 35 industrialized reduce 5% below 1990 by 2012. Bounds emissions. Expanded: Efforts reduce GHGs, arrest warming.
11. Describe Am tropical monsoon.
4 Marks Answer: Indian subcontinent/NE S America/N Australia; heavy summer rain, dry winter. Wind reversal. Expanded: Detailed in India book; agriculture rhythm.
12. What is Cfa climate?
4 Marks Answer: Humid subtropical east subtrop; unstable air rain year-round 75-150cm. 27°C summer/5-12°C winter, small daily range. Expanded: Thunderstorms summer, fronts winter.
13. Explain volcanism cause.
4 Marks Answer: Eruptions throw aerosols atmosphere reduce solar reaching earth, cooling years. E.g. Pinatubo/El Chichon. Expanded: Temporary effect.
14. Describe past climate India.
4 Marks Answer: Wet cool 8000BC Rajasthan; higher rain 3000-1700BC Harappan; dry after 2000BC. Alternate wet/dry. Expanded: Archaeological evidence.
15. What is Little Ice Age?
4 Marks Answer: 1550-1850 Europe cold wet; Vikings Greenland settled warm 10-11th cent. Expanded: Solar/volcanic linked.
16. Explain Milankovitch.
4 Marks Answer: Cycles earth's orbit/sun, wobble, axial tilt alter insolation. Bearing climate long-term. Expanded: Triggers glacials.
17. What is ozone role?
4 Marks Answer: Stratosphere absorbs UV; troposphere GHG absorbs terrestrial. CFCs destroy. Expanded: Hole allows UV.
18. Describe Aw climate.
4 Marks Answer: Tropical wet-dry; shorter wet, longer dry, severe drought. High temps, greatest diurnal dry season. Deciduous forests/grasslands. Expanded: Borders Af west, Cf east.
19. What is Df climate?
4 Marks Answer: Cold humid winter; cold snowy, short frost-free, large ranges. Abrupt weather. Expanded: Poleward more severe.
20. Explain recent warming.
4 Marks Answer: +0.6°C end 19th to 20th cent; 1998 warmest. Periods 1901-44/1977-99 +0.4°C each. Expanded: 1990s extremes.
21. What is BSh steppe?
4 Marks Answer: Subtropical semi-arid; more rain than desert, sparse grasslands. High variability famine. Expanded: Transition humid-dry.
22. Describe Cfb.
4 Marks Answer: Marine west coast poleward Cs; moderate marine influence, warmer winter latitude. Small ranges, rain year-round 50-250cm. Expanded: NW Europe/N America.
Part C: 8 Marks Questions
1. Discuss Koeppen's classification scheme in detail.
8 Marks Answer: Empirical 1918 modified; based mean annual/monthly temp/precip relating vegetation distribution. Capital letters groups: A tropical (coldest ≥18°C), B dry (evap>precip), C warm temperate (coldest -3 to 18°C), D cold snow forest (≤-3°C), E cold (<10°C all). Small letters types: f no dry, m monsoon short dry, w winter dry, s summer dry; a b c d temp severity (a hottest >22°C, d coldest <-3°C severe). B subdivided S steppe semi-arid, W desert arid; h hot, k cold. Expanded: Values selected e.g. A humid hot; popular use, vegetation link; critiques ignore winds/extremes but educational value high. Table 11.1 characteristics, 11.2 types/codes. Global distribution shown maps.
2. Analyze Group A tropical humid climates.
8 Marks Answer: Between Tropics Cancer/Capricorn; ITCZ overhead year, hot humid, low annual temp range, high rain. Types: Af wet equator (Amazon/Africa/Indies; monthly thunder showers afternoon, uniform 30°C max/20°C min, evergreen forests dense canopy biodiversity); Am monsoon (Indian sub/NE S America/N Australia; heavy summer rain mostly, dry winter, wind reversal, detailed India book); Aw wet-dry (N/S Af borders, Amazon N/S Brazil/Paraguay/Bolivia, Sudan/C Africa; shorter wet longer dry severe drought, high temps greatest diurnal dry, deciduous forests/tree-shredded grasslands). Expanded: Sun overhead constant; human agriculture wet seasons, deforestation threats; biodiversity hotspots Af, monsoons rhythm farming Am.
3. Examine dry climates B and subdivisions.
8 Marks Answer: Low rain inadequate plants growth; large area 15-60° N/S equator, subsidence highs low lat, cold currents west coasts equatorward, interiors/mountains mid lat block moisture. Divided BS steppe semi-arid, BW desert arid; subtropical BSh/BWh 15-35° transition humid-dry, more rain steppe sparse grasslands, variability high famine risks, thundershowers ineffective soil moisture, fog coastal bordering cold currents; mid-lat BSk/BWk 35-60° confined interiors. Temps summer very high e.g. 58°C Al Aziziyah Libya 1922, annual/diurnal large. Expanded: Subsidence inversion no rain; cold currents e.g. Peru/Chile; nomadic deserts, grazing steppes; irrigation potential oases.
4. Discuss warm temperate mid-latitude climates C.
8 Marks Answer: 30-50° mainly east/west margins continents; warm summers mild winters. Types: Cwa humid subtropical winter dry hot summer (poleward Tropics, N India/S China plains; similar Aw but warm winter); Cs Mediterranean (Med sea/C California/C Chile/SE SW Australia; subtropical high summer dry hot, westerlies winter mild rainy, 25°C summer/<10°C winter, 35-90cm precip); Cfa humid subtropical no dry mild winter (E continents subtrop, E US/S E China/S Japan/NE Argentina/coastal S Africa/E Australia; unstable air rain year-round thunderstorms summer fronts winter, 75-150cm, 27°C summer/5-12°C winter small daily range); Cfb marine west coast (poleward Cs west, NW Europe/W coast N America N California/S Chile/SE Australia/NZ; marine moderate, warmer winter lat, 15-20°C summer/4-10°C winter small ranges, precip year 50-250cm). Expanded: Vegetation adapts e.g. evergreen Cs; agriculture fruits Cs, mixed Cfb; air masses influence.
5. Analyze cold climates D and E.
8 Marks Answer: D cold snow forest 40-70°N large continental Europe/Asia/N America; Df cold humid winter (poleward marine west/steppe, cold snowy short frost-free large ranges, abrupt weather, poleward severe); Dw cold dry winter (NE Asia; anticyclone winter weakening summer monsoon reversal, lower summer temps extremely low winter below freeze 7 months, precip summer 12-15cm). E polar >70°; ET tundra (vegetation low mosses/lichens/flowers, permafrost subsoil frozen, short grow water logging, long summer daylight); EF ice cap (interior Greenland/Antarctica; below freeze summer, little precip, snow/ice accumulate pressure deforms breaks icebergs float Arctic/Antarctic, Plateau Station portrays). Expanded: Severity higher lat D; taiga Df; no trees ET fragile; research EF; human limited herding ET, stations EF.
6. Examine causes of climate change.
8 Marks Answer: Astronomical: Sunspots cycle (increase cooler wetter storms, decrease warm drier, not significant); Milankovitch oscillations (orbital eccentricity, axial tilt, precession alter insolation bearing climate); terrestrial: Volcanism (eruptions aerosols atmosphere reduce solar reaching surface cooling years e.g. Pinatubo/El Chichon); GHGs increasing concentration (anthropogenic main, CO2 fuels/deforestation, CFCs ozone, CH4, N2O, O3; warm earth). Expanded: Sunspots dark cooler patches; Milankovitch long cycles trigger glacials; volcanism temporary; GHGs most important now, doubling CO2 index models.
7. Discuss global warming and impacts.
8 Marks Answer: Atmosphere behaves greenhouse transmitting solar absorbing longwave from earth; GHGs CO2/CFCs/CH4/N2O/O3 trap heat. Analogy glasshouse/car closed warmer. CO2 largest from fossil combustion/deforestation sinks forests/oceans; rising 0.5% annually, adjust 20-50 years. CFCs destroy ozone hole Antarctica allow UV. Warming +0.6°C 19th-20th cent, uneven; difficult reverse. Impacts: Sea level rise melt glaciers/ice-caps thermal expansion inundate coasts/islands social problems; biodiversity loss, extreme events. Expanded: Effectiveness concentration/lifetime; Kyoto reduce; hope lifestyle changes livable world.
8. Analyze evidence of climate change.
8 Marks Answer: Geological: Alternation glacial/interglacial periods; geomorphology high alt/lat advances/retreats glaciers; sediments glacial lakes warm/cold. Tree rings wet/dry; historical records vagaries. India: Wet cool 8000BC Rajasthan, higher rain 3000-1700BC Harappan center, dry accentuated 2000-1700BC. Past: Warm 500-300 mya Cambrian-Ordovician-Silurian; Pleistocene glacials, last peak 18,000 ya, present interglacial 10,000 ya. Recent: 1990s extremes warmest century, Sahel drought 1967-77, Dust Bowl 1930s SW US Plains, Little Ice Age 1550-1850 Europe, warm dry 10-11th cent Vikings Greenland, upward 1885-1940, slow after. Expanded: Crop yields/floods/migration tell effects; natural continuous process.
9. Compare A and B types of climate.
8 Marks Answer: A tropical humid: Coldest ≥18°C, between Tropics, ITCZ hot humid low temp range high annual rain; types Af wet no dry evergreen forests, Am monsoon summer rain dry winter, Aw wet-dry shorter wet longer dry deciduous grasslands; examples Amazon/India/Sudan. B dry: Evap>precip, 15-60° subsidence/cold currents/interiors, low rain inadequate plants high variability; types BS steppe semi-arid sparse grass famine risks, BW desert arid barren; subtropical BSh/BWh 15-35° transition thundershowers ineffective fog coastal high summer temps large ranges; mid-lat BSk/BWk 35-60° mountains block. A wet vegetated biodiverse; B dry sparse extreme temps. Expanded: A agriculture possible; B irrigation/nomadic; A low ranges uniform, B high diurnal.
10. What vegetation in C and A climates?
8 Marks Answer: A tropical: Af evergreen dense canopy large biodiversity Amazon/Africa; Am similar but some shedding monsoon areas; Aw deciduous forests tree-shredded grasslands Brazil/Sudan. C warm temperate: Cwa similar Aw but warmer winter N India/China; Cs Mediterranean evergreen shrubs/trees adapted dry summer e.g. olives/grapes California/Chile; Cfa deciduous broadleaf unstable air E US/China; Cfb coniferous/mixed forests moderate rain NW Europe/N America. A high rain dense tropical; C milder varied adapted seasons. Expanded: A biodiversity hotspots; C commercial fruits/forestry; influences human activities e.g. wine Cs.
11. Explain greenhouse gases list.
8 Marks Answer: GHGs absorb longwave: CO2 (fossil fuels/deforestation, sinks forests/oceans, rising 0.5% annually, 20-50 years adjust, doubling index models); CFCs (human products, destroy ozone stratosphere, high effective, drift up); CH4 (methane rice/livestock/landfills); N2O (nitrous oxide fertilizers/soils); O3 (ozone troposphere absorbs terrestrial, stratosphere UV). Also NO/CO react affect concentration. Effectiveness magnitude increase/lifetime/wavelength; CFCs/O3 very effective, longer lifetime slower recovery. Expanded: Primary concern warming; international efforts Kyoto reduce.
12. Discuss climate in recent past.
8 Marks Answer: Variability always; 1990s extreme events warmest century worst floods. Sahel drought 1967-77 S Sahara; Dust Bowl 1930s SW US Plains erosion crop failure; Europe warm wet cold dry periods, warm dry 10-11th cent Vikings Greenland settled; Little Ice Age 1550-1850 cold wet; upward trend 1885-1940, slow after. Historical crop yields/failures/floods/migration tell changing effects. Expanded: N Hemisphere cooling marked between periods; evidences indicate natural continuous.
13. Analyze astronomical causes change.
8 Marks Answer: Solar output changes sunspot activities: Dark cooler patches cycle increase/decrease; increase cooler wetter greater storminess, decrease warm drier; findings not statistically significant. Milankovitch oscillations: Cycles variations earth's orbital characteristics sun, wobbling, changes axial tilt; alter amount insolation received, bearing climate e.g. trigger glacials/interglacials. Expanded: Sunspots 11-year cycle; Milankovitch long-term 100,000/41,000/26,000 years; explain past variations like Pleistocene epochs.
14. Examine terrestrial causes.
8 Marks Answer: Volcanism: Eruptions throw aerosols atmosphere remain considerable time reducing sun's radiation reaching surface, cooling some years e.g. recent Pinatubo/El Chichon fell average temp. GHGs increasing trend concentration atmosphere likely cause global warming; most important anthropogenic effect. Expanded: Aerosols reflect solar; GHGs CO2 etc. trap heat; volcanism temporary, GHGs long-term persistent.
15. Discuss ozone depletion impacts.
8 Marks Answer: Ozone stratosphere converts oxygen UV rays, absorbs not reach surface; CFCs drift destroy, large depletion Antarctica called ozone hole allows UV pass troposphere. Impacts: Increased UV skin cancer/eye damage/crops/marine life. International efforts Montreal protocol phase out CFCs; recovery ongoing. Expanded: O3 troposphere GHG; hole seasonal spring; links warming as CFCs also GHGs.
16. Analyze global warming trends.
8 Marks Answer: Annual average near-surface air temp world ~14°C; increasing 20th cent greatest two periods 1901-44/1977-99 +0.4°C each, slight cooling between marked N Hemisphere. End 20th cent +0.6°C above end 19th; seven warmest 1856-2000 last decade, 1998 warmest century/millennium. Expanded: 1990s recorded warmest extremes; concerns uniform not, adverse life support e.g. sea rise social problems.
17. Examine Kyoto declaration.
8 Marks Answer: Proclaimed 1997, effect 2005 ratified 141 nations; bounds 35 industrialized countries reduce emissions year 2012 5% less 1990 levels. International effort reducing GHGs atmosphere. Expanded: Response warming; Paris 2015 successor ambitious; challenges implementation developing nations; aims arrest trend global warming difficult reverse once sets in.
18. Discuss vegetation A climates.
8 Marks Answer: Af tropical wet: Evergreen forests dense canopy large biodiversity Amazon basin/w equatorial Africa/E Indies islands. Am tropical monsoon: Similar but adapted short dry, some shedding Indian sub/NE S America/N Australia. Aw tropical wet-dry: Deciduous forests tree-shredded grasslands N/S Amazon forest Brazil/Paraguay/Bolivia/Sudan/C Africa. High rain supports lush veg; biodiversity decreases dry increases. Expanded: Adaptations canopy rain protection; human deforestation threats agriculture suits wet.
19. Compare C and A climates.
8 Marks Answer: A tropical: Coldest ≥18°C hot humid low range high rain year-round; veg evergreen/deciduous biodiverse; locations equator Tropics. C warm temperate: Coldest -3 to 18°C warm summers mild winters; types Cwa winter dry, Cs summer dry Med, Cfa no dry, Cfb marine; veg evergreen shrubs Cs, deciduous Cfa, mixed Cfb; locations 30-50° margins. A constant heat/rain; C seasonal milder. Expanded: A biodiversity high; C commercial crops; A no frost, C possible mild.
20. Explain project on Kyoto.
8 Marks Answer: Collect information Kyoto declaration global climate changes: 1997 UN framework, aims reduce GHGs industrialized 5.2% average 1990 levels 2008-2012 first period; 37 countries Annex I commitments, mechanisms trading/clean development. Successor Paris; impacts policies renewable/carbon tax. Expanded: Challenges US non-ratify; India/China emerging emitters; relevance warming mitigation sea rise/extremes.
21. Analyze impacts warming.
8 Marks Answer: Uneven everywhere; adverse life support rise sea level melt glaciers/ice-caps thermal expansion inundate large coastal areas/islands leading social problems displacement/migration. Biodiversity loss habitats shift, extreme events floods/droughts increase. Expanded: Agriculture yields change, water scarcity, health diseases spread; economic costs disasters; vulnerable small islands/lowlands e.g. Maldives/Bangladesh.
Tip: Use tables for groups/types; examples world/India; causes classify astronomical/terrestrial. Expanded with critiques, applications.
