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Chapter 8: Climate and Climate Change

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Climate Classification Purpose of Classifying Climates Understand climate distribution Compare climates of different places Temperature & precipitation typically used Vegetation Earliest scheme = ancient Greeks 2200 years ago Classified 3 climate regions based on latitude Torrid, Temperate, Frigid Figure 8-1

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Climate Classification Kppen climate classification system Based on annual & monthly average temperature & precipitation A, B, C, D, E, H* 4 of 5 major groups classified by temperature 5 th group classified by precipitation Subdivided further based on temperature & precipitation relationships Figure 8-2

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Climate Classification Kppen 3 letter code system 1 st = group 2 nd = precipitation 3 rd = temperature

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World Distribution of Major Climate Types Figure 8-11 Weather records: How do we explain their locations?

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Three Questions Where are various climate types located? What are the characteristics of each climate? What are the main controls of each climate? Climograph Graphic representation of monthly temperature & precipitation World Distribution of Major Climate Types Figure 8-4

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World Distribution of Major Climate Types Tropical Humid Climates (A) Tropics (0-25 N/S) Winterless climates; little temperature change High temperatures & prevalent moisture Precipitation influenced by ITCZ 3 subtypes Divided based on monthly rainfall Figure 8-5

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World Distribution of Major Climate Types Tropical wet climate (Af) Equatorial (0-10 N/S) Monotonous Daily temperature range > annual range High humidity High precipitation Multiple rains daily Afternoon convective storms Evenly distributed rain during year Influenced by ITCZ High solar angle year round Figures 8-6a & b

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World Distribution of Major Climate Types Tropical savannah climate (Aw) N/S of Af climates Most extensive A climate Seasonal wet/dry alteration due to ITCZ position Lowest tropical rainfall amounts Dominant Controls Summer: ITCZ Winter: cT or cP air masses Figures 8-8a & b

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World Distribution of Major Climate Types Tropical monsoonal climate (Am) Prominent monsoon wind patterns Coastal areas Extensive rainfall during summer Cherrapunji, India = 425 in Cloud cover reduces summer temperatures Dominant Controls ITCZ movement Jet stream fluctuation Continental pressure changes Figures 8-10a & b

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World Distribution of Major Climate Types Dry climates (B) Cover about 30% of land area worldwide Dry conditions all year PE > P Lack of uplift or lack of moisture 2 main types (precipitation) Desert Steppe 2 subtypes (temperature) Subtropical Midlatitude Figure 8-12

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World Distribution of Major Climate Types Subtropical desert climate (BWh) Near STHs (30 N/S) Precipitation is scarce, unreliable, intense & short- lived Hot temperatures Large daily temperature range Dominant Controls Subsidence from (STHs) Cold ocean currents Figures 8-14a & b

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World Distribution of Major Climate Types Subtropical steppe climate (BSh) Fringe BWh climates Separate deserts from humid climates Less extremes Cooler & more rainfall (semi-arid) Seasonal rainfall concentration Dominant Controls Similar to BWh Figure 8-17

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World Distribution of Major Climate Types Midlatitude desert climate (BWk) Meager & erratic precipitation Mostly in summer Cooler temperatures Hot summers & cold winters Greater annual & daily temperature range Dominant Controls Rain shadow effects Distance from moisture sources Figures 8-18a & b

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World Distribution of Major Climate Types Midlatitude steppe climate (BSk) Rringe BWk climates Transition between desert & humid climates More precipitation than mid- latitude deserts (semi-arid) Less temperature extremes than mid- latitude deserts Dominant Controls Similar to BWk Figure 8-19

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World Distribution of Major Climate Types Mild Midlatitude Climates (C) Transition between warmer tropical climates & colder severe midlatitude climates Equator-ward side of mid-latitudes Long, hot summers & short, mild winters Highly variable precipitation 3 primary groups Figure 8-20

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World Distribution of Major Climate Types Mediterranean Climate (Csa, Csb) West sides of continents Modest precipitation in winter, summer is virtually rainless Mild, wet winters & hot, dry summers Clear skies especially in summer Dominant Controls Summer: STH Winter: westerlies & cyclones Figures 8-21a & b

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World Distribution of Major Climate Types Humid Subtropical Climate (Cfa, Cwa) East sides of continents Warm to hot summers; high humidity Hot & humid Precipitation reaches summer maximum, less in winter Winter temperatures are mild to cold Figures 8-24a & b

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World Distribution of Major Climate Types Marine West Coast Climate (Cfb, Cfc) West sides of continents Often cloudy with precipitation Wettest of midlatitudes Max precipitation in winter Temperate climate Very mild winters for latitude Dominant Controls Westerly winds & oceanic influence year-round Figures 8-26a & b

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World Distribution of Major Climate Types Severe Midlatitude Climates (D) Only in Northern Hemisphere Continentalityremoteness from oceans Large annual temperature range Precipitation varies; diminishes inland & poleward 4 recognizable seasons Long, cold winter & shorter summer Subdivided into 2 types Figure 8-27

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World Distribution of Major Climate Types Humid Continental Climate (Dfa, Dfb, Dwa, Dwb) East sides of continents in N. Hemisphere Dominated by westerlies & frequent weather changes Warm/hot summers, cold winters Large annual temperature range Generally low precipitation Higher near coasts Winter precipitation = cyclones; summer precipitation = convection Our climate in NE Figures 8-28a & b

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World Distribution of Major Climate Types Subarctic Climate (Dfc, Dfd, Dwc, Dwd) Winters are long, dark, bitterly cold Summers are short Spring & fall are very short Coldest temperatures; little precipitation Largest annual temperature ranges (-90 F to 98 F in Verhoyansk, Siberia) Dominant Controls Continentality Alternate between: Westerlies/storms Anticylcones Figures 8-31a & b

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World Distribution of Major Climate Types Polar Climates (Group E) Receive little insolation Coldest summers No average temperature above 50 F Large annual temperature range Small daily temperature range Extremely dry, but classified as non-arid Low evaporation 2 primary groups Figure 8-27

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World Distribution of Major Climate Types Tundra Climate (ET) Long, dark winters Winters not as severely cold as subarctic climate Brief, cool summers Little precipitation Dominant Controls Latitude Distance from heat/moisture sources Extreme contrasts in sunlight/darkness Polar anticyclones (A & cP air masses) Figures 8-33a & b

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World Distribution of Major Climate Types Ice Cap Climate (EF) Greenland & Antarctica Permanent ice & snow cover High latitude with high altitude Very limited precipitation Polar deserts Dominant Controls Similar to ET Figures 8-34a & b

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World Distribution of Major Climate Types Highland Climate (H) Infinite variations from place to place Vertical climate zonation Altitude vs. Latitude Altitude = more significant in highlands -6.5C /1000m Exposure: windward or leeward Figure 8-36

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Global Patterns Idealized Understand climate locations & relationships Presumed arrangement of climate types on hypothetical continent Example: Africa Only continent with equal land N/S of equator Figures 8-39 & 40

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Global Climate Change Changes in climate on long time scales Episodic events vs. long-term global climate change Numerous time scales 70 million years: global cooling trend 150,000 years: temperature fluctuated 10,000 years: sharp warmup 150 years: warming trend relative to last 1000 years Figure 8-41

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Global Climate Change Paleoclimatology Proxy measures of climate Dendrochronology Study of past climate via tree ring analysis Oxygen isotope analysis/Ice cores Lighter vs. heavier isotopes ( 18 O : 16 O) Ratio of 18 O/ 16 O = thermometer Atmospheric composition measurements Coral reefs Ratio of 18 O/ 16 O & reef height Pollen data Radiocarbon dating Figure 8-42

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Global Climate Change Causes of Long-Term Climate Change Atmospheric aerosols Block insolation & lower temperature Due to volcanic eruptions or asteroid impacts Anthropogenic impacts Solar output fluctuations Sunspot activity vs. solar output Roles of the oceans Absorb large amounts of carbon Methane hydrates Heat transfer from low latitudes to high latitudes Figures 8-43 & 45

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Global Climate Change Climate change causes (cont.) Greenhouse gas concentrations Greenhouse gas concentrations related to temperature Evidence of CO 2 increase being anthropogenic Feedback mechanisms Positive feedback mechanisms Negative feedback mechanisms Variations in Earth-Sun relations Milankovitch cycles Shape of Earths orbit (eccentricty) Inclination of Earths axis (obliquity) Position of Earths axis (precession) Figure 8-44

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Global Climate Change Evidence of global warming 11 of 12 warmest years on record occurred between 19952006 Global temperature increasing Arctic temps 2 xs global rate Ocean temperatures increasing Sea level rise Thermal expansion Melting ice caps & glaciers Arctic sea ice decreasing # of intense tropical cyclones Water vapor in atmosphere Changes in precipitation amounts Figures 8-46a & b

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Global Climate Change Evidence of current global warming (cont.) Concentrations of carbon dioxide correlated with temperature Carbon dioxide concentrations correlate with increased anthropogenic greenhouse gases Carbon dioxide increasing at a rate faster than observed in last 800,000 years Figure 8-F

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Global Climate Change Consequences of global warming Projected climate in the upcoming century Climate will warm about 0.4F per decade Changes will be greater than those during 20 th c. Estimated temperature increase from 3.3F - 7.2F Sea level rise Stronger tropical cyclones Increased precipitation Figure 8-47a

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Global Climate Change Climate models General circulation models (GCMs) Numerous assumptions Model accuracy Addressing global warming Kyoto protocol Standards for new industrialized countries Mitigating & adapting Figure 8-47b

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Summary Climate is classified based on precipitation and temperature There are six primary groups of world climates The tropical humid climates exist at tropical latitudes and are characterized by warm, constant temperatures and rainfall Dry climates exist near the subtropics and are characterized by hot, dry conditions Mild midlatitude climates constitute a transition between warmer tropical climates and cold severe midlatitude climates Mild midlatitude climates typically have long, hot summers & mild winters, and have modest precipitation Severe midlatitude climates only occur in the Northern Hemisphere Severe midlatitude climates have long, cold winters and short summers, and have large annual temperature ranges Polar climates receive little insolation and are permanently cold and dry Highland climates depend on elevation of mountainous terrain for their climate characteristics Many paleoclimatology methods are used to understand the Earths past climate There are several factors that influence long-term climate change Global warming is related to the increase in carbon dioxide release by humans