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    Ch08 Ch08 Presentation Transcript

    • © 2011 Pearson Education, Inc.Chapter 8: Climate andClimate ChangeMcKnight’s Physical Geography:A Landscape Appreciation,Tenth Edition, Hess
    • © 2011 Pearson Education, Inc.Climate and Climate Change2• Climate Classification• World Distribution of Major Climate Types• Global Patterns Idealized• Global Climate Change
    • © 2011 Pearson Education, Inc.Climate Classification• Need a consistent climateclassification scheme tounderstand numerous climateregions• Earliest known scheme wasby the ancient Greeks 2200years ago• Classified three major climateregions3Figure 8-1
    • © 2011 Pearson Education, Inc.Climate Classification• Köppen climate classification system• Based on a database of annual and monthly averagetemperature and precipitation• Four of five major groups classified by temperature• Fifth group classified by precipitation• Subdivided the five groups further based ontemperature and precipitation relationships• Köppen letter code system– Three letters; first describes group, second describesprecipitation, third describes temperature• Climographs4
    • © 2011 Pearson Education, Inc.Climate Classification5Figure 8-2• The modified Köppen classification system
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types6Figure 8-11• Weather records. How do we explain their locations?
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Tropical Humid Climates(Group A—Figure 8-5)– Molded by the tropicallatitudinal regions– Winterless climates; littletemperature change– Moisture is prevalent– Precipitation influencedby ITCZ– Three subtypes7Figure 8-5
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Tropical wet climate (Af)– Equatorial– Monotonous climate– Daily temperature rangeexceeds annual range– High humidity– Rainfall multiple times aday– High solar angle yearround; ITCZ influencesrainfall8Figure 8-6bFigure 8-6a
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Tropical savannahclimate (Aw)– Lies north and south ofAf climates– Seasonal alteration ofwet and dry periods dueto position changes ofITCZ– Smallest rainfallamounts of tropicalregions9Figure 8-8bFigure 8-8a
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Tropical monsoonalclimate (Am)– Regions with prominentmonsoonal wind pattern– Extensive rainfall duringhigh-Sun season– Cherrapunji, Indiaaverages 425 inches– Cloud cover reducestemperatures slightly insummer versus spring10Figure 8-10bFigure 8-10a
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Dry climates (Group B –Figure 8-12)– Cover about 30% ofland area worldwide– Lack of uplift or lack ofmoisture– Typical in subtropics– Marine deserts– Two main types, twosubtypes11Figure 8-12
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Subtropical desert climate(BWh)– Lie near subtropical highs– Precipitation is scarce(rare) and unreliable(highly variable)– Precipitation that doesform is short lived andintense– Hot temperatures– Large diurnal range oftemperature12Figure 8-14bFigure 8-14a
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Subtropical steppe climate(BSh)– Typically surrounds BWhclimates– Separate desert climatefrom humid climate– Extremes are muted insteppe regions• Cooler temperatures• More rainfall– Seasonal concentrationof rainfall13Figure 8-17
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Midlatitude desert climate(BWk)– Far removed from oceanicinfluence– Meager and erraticprecipitation– Most precipitation occursin summer– Cold winters, overallcooler temperatures– Greater annualtemperature range14Figure 8-18aFigure 8-18b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Midlatitude steppe climate(BSk)– Occupies transitionsbetween desert andhumid climates– Greater precipitation thanmidlatitude deserts– Less temperatureextremes than midlatitudedeserts15Figure 8-19
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Mild Midlatitude Climates(Group C—Figure 8-20– Transition betweenwarmer tropical climatesand colder severemidlatitude climates– Hot summers, mildwinters– Highly variableprecipitation amounts– Three primary groups16Figure 8-20
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Mediterranean Climate(Csa, Csb)– Modest annualprecipitation in winter,summer is virtually rainless– Mild winters and hotsummers– Clear skies especially insummer– Most is Csa (hotsummers); Csb climateshave mild summers andare more coastal 17Figure 8-21aFigure 8-21b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Humid Subtropical Climate(Cfa, Cwa)– Warm to hot summers;high humidity (Cfa days arehot and sultry)– Precipitation reachessummer maximum, somedrop off for winter– Winter temperatures in Cfaregions are mild; typicallycooler than mediterraneanclimates18Figure 8-24aFigure 8-24b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Marine West Coast Climate(Cfb, Cfc)– Influenced by onshore flowfrom midlatitude westerlies– Occurs when no topographicboundaries inhibit flow ofmaritime air inland– Frequently cloudy withprecipitation– Temperate climate– Wettest of the midlatitudes19Figure 8-26aFigure 8-26b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Severe MidlatitudeClimates (Group D)– Only in NorthernHemisphere– Continentality—remoteness from oceans– Four recognizableseasons; long, cold winterand short summer– Subdivided into two typesbased on temperature20Figure 8-27
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Humid Continental Climate(Dfa, Dfb, Dwa, Dwb)– Dominated by westerlies andassociated frequent weatherchanges– Warm summers, cold winters– Generally low precipitation;higher amounts near coasts– Winter precipitationassociated with cyclones;summer with convection21Figure 8-28aFigure 8-28b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Subarctic Climate (Dfc, Dfd,Dwc, Dwd)– Winters are long, dark, andbitterly cold– Summers are short; springand fall pass quickly– Coldest temperatures; littleprecipitation– Largest annual temperatureranges (i.e., -90 °F to 98 °Fin Verhoyansk, Siberia)22Figure 8-31aFigure 8-31b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Polar Climates (Group E)– Receive little insolation– No average temperatureabove 50 °F– Extremely dry, butclassified as nonarid– Two primary groups23Figure 8-27
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Tundra Climate (ET)– Southern boundary the“treeline”– Northern boundary borderof any plant cover– Long, dark winters– Brief, cool summers– Little precipitation– Winters not as severelycold as subarctic climateregion24Figure 8-33aFigure 8-33b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Ice Cap Climate (EF)– Mainly Greenland andmost of Antarctica– Permanent cover of iceand snow– Ice plateaus; high latitudewith high altitude– Very limited precipitation,essentially polar deserts25Figure 8-34aFigure 8-34b
    • © 2011 Pearson Education, Inc.World Distribution of MajorClimate Types• Highland Climate(Group H)– Nearly infinite variationsfrom place to place– Altitude more significantthan latitude in highlands– Exposure (whether aslope is windward orleeward)– High diurnal temperaturevariations due to thin, dryair26Figure 8-36
    • © 2011 Pearson Education, Inc.Global Patterns Idealized• Presumed arrangement of Köppen climate types on ahypothetical continent (Figure 8-40)27Figure 8-40
    • © 2011 Pearson Education, Inc.Global Climate Change• Changes in climate on long time scales• Weather is noise, climate is long-term signal• Episodic events (i.e., El Niño and the PDO) versuslong-term global climate change• Numerous time scales to consider (i.e., temperature)– 70 million years, clear global cooling trend– 150,000 years, temperature fluctuated– 10,000 years, sharp warmup– 150 years, warming trend relative to last 1000 years28
    • © 2011 Pearson Education, Inc.Global Climate Change• Paleoclimatology– Proxy measures ofclimate (i.e., ice cores,tree rings)• Dendrochronology—study of past climatethrough tree ring analysis• Oxygen isotope analysis– Lighter versus heavierisotopes– High 18O/16O ratio,glaciation29Figure 8-41
    • © 2011 Pearson Education, Inc.Global Climate Change• Coral reefs– Ratio of 18O/16O in coral reefs– Height of old reefs• Ice cores– Ratio of 18O/16O serves as athermometer– Provide direct atmosphericcomposition measurements• Pollen data– Radiocarbon dating30Figure 8-42
    • © 2011 Pearson Education, Inc.Global Climate Change• Causes of Long-TermClimate Change– Atmospheric aerosols• Large quantities of aerosolscan block insolation and lowertemperature• Result from volcaniceruptions or asteroid impacts• Anthropogenic impacts31Figure 8-43
    • © 2011 Pearson Education, Inc.Global Climate Change• Climate change causes (cont.)– Solar output fluctuations• Sunspot activity related to solaroutput– Variations in Earth-Sunrelations• Shape of Earth’s orbit• Inclination of Earth’s axis• Precession of Earth’s axis• Milankovitch cycles32Figure 8-44
    • © 2011 Pearson Education, Inc.Global Climate Change• Climate change causes (cont.)– Greenhouse gas concentrations• Greenhouse gas concentrations related to temperature• Evidence of CO2 increase being anthropogenic– Feedback mechanisms• Positive feedback mechanisms• Water vapor feedback challenges33
    • © 2011 Pearson Education, Inc.Global Climate Change• Climate change causes (cont.)– Roles of the oceans• Absorb large amounts of carbon• Methane hydrates• Heat transfer from low latitudesto high latitudes• Climate models– General circulation models(GCMs)– Numerous assumptions– Accuracy of the models34Figure 8-45
    • © 2011 Pearson Education, Inc.Global Climate Change• Evidence of current globalwarming– 11 of 12 warmest years onrecord occurred between 1995–2006– Global temperature increasing at0.13 °C per decade– Ocean temperatures increasingto depths of 9800 feet– Sea level rise– Temperatures in Arctic increasingat twice global rate35Figure 8-46a
    • © 2011 Pearson Education, Inc.Global Climate Change• Evidence of current globalwarming (cont.)– Sea ice in Arctic decreasing by7.4 percent per decade– Ice caps and glacier melt leadingto sea level rise– Temperatures on top of apermafrost layer have increasedby 5.4 °F– Number of intense tropicalcyclones increased since 1970– Amount of water vapor inatmosphere increased– Changes in precipitation amounts36Figure 8-46b
    • © 2011 Pearson Education, Inc.Global Climate Change• Evidence of current global warming (cont.)– Concentrations of carbon dioxide correlated with temperature– Carbon dioxide concentrations correlate with increasedanthropogenic greenhouse gases– Carbon dioxide increasing at a rate faster than observed in last800,000 years37
    • © 2011 Pearson Education, Inc.Global Climate Change• Consequences of globalwarming– Projected climate in theupcoming century• Climate will warm at about 0.4 °Fper decade• Changes will be greater thanthose observed during 20thcentury• Estimated increase oftemperature from 3.3 °F to 7.2 °F• Sea level rise• Stronger tropical cyclones• Increased precipitation38Figure 8-47a
    • © 2011 Pearson Education, Inc.Global Climate Change• Addressing global warming– Kyoto protocol– Standards for newlyindustrialized countries– Mitigating and adapting39Figure 8-47b
    • © 2011 Pearson Education, Inc.Summary• Climate is classified based on precipitation andtemperature• There are six primary groups of world climates• The tropical humid climates exist at tropical latitudes andare characterized by warm, constant temperatures andrainfall• Dry climates exist near the subtropics and arecharacterized by hot, dry conditions• Mild midlatitude climates constitute a transition betweenwarmer tropical climates and cold severe midlatitudeclimates40
    • © 2011 Pearson Education, Inc.Summary• Mild midlatitude climates typically have long and hotsummers and mild winters, and have modestprecipitation• Severe midlatitude climates only occur in the NorthernHemisphere• Severe midlatitude climates have long, cold winters andshort summers, and have large annual temperatureranges• Polar climates receive little insolation and arepermanently cold and dry41
    • © 2011 Pearson Education, Inc.Summary• Highland climates depend on elevation of mountainousterrain for their climate characteristics• Many paleoclimatology methods are used to understandthe Earth’s past climate• There are several factors that influence long-termclimate change• Global warming is related to the increase in carbondioxide release by humans42