chapter 21 global climate change. overview of chapter 21 introduction to climate change causes of...
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Chapter 21Chapter 21Global Climate ChangeGlobal Climate Change
Overview of Chapter 21Overview of Chapter 21
Introduction to Climate ChangeIntroduction to Climate Change Causes of Global Climate ChangeCauses of Global Climate Change
Effects of Climate ChangeEffects of Climate Change Melting Ice and Rising Sea LevelMelting Ice and Rising Sea Level Changes in Precipitation PatternsChanges in Precipitation Patterns Effects on OrganismsEffects on Organisms Effects on Human HealthEffects on Human Health Effects on AgricultureEffects on Agriculture
Dealing with Global Climate ChangeDealing with Global Climate Change
Climate Change Climate Change TerminologyTerminology Greenhouse GasGreenhouse Gas
Gas that absorbs infrared radiationGas that absorbs infrared radiation Positive FeedbackPositive Feedback
Change in some condition triggers a response Change in some condition triggers a response that intensifies the changed condition that intensifies the changed condition
Infrared RadiationInfrared Radiation Radiation that has a wavelength that is longer Radiation that has a wavelength that is longer
than that of visible light, but shorter than that of than that of visible light, but shorter than that of radio waves radio waves
Greenhouse EffectGreenhouse Effect Increase of heat in a system where energy enters Increase of heat in a system where energy enters
(often as light), is absorbed as heat, and released (often as light), is absorbed as heat, and released sometime later sometime later
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate: 1.1. Latitude: Latitude:
• near equator is warm, near poles is cold, because near equator is warm, near poles is cold, because at equator the Sun strikes Earth at a at equator the Sun strikes Earth at a higher angle higher angle of insolationof insolation, at poles Sun strikes Earth at a , at poles Sun strikes Earth at a lower angle of insolationlower angle of insolation
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:
1.1. Latitude…continued: Latitude…continued: • Seasons on Earth are determined by Seasons on Earth are determined by
latitude and angle of insolation at various latitude and angle of insolation at various times throughout the year, and are caused times throughout the year, and are caused by:by:• Tilt of Earth’s axisTilt of Earth’s axis
• Earth’s revolution around the SunEarth’s revolution around the Sun
• Parallelism of Earth’s axisParallelism of Earth’s axis
Seasons on Earth…Seasons on Earth…
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:
2.2. Proximity to a large body of water Proximity to a large body of water (ocean or large lake):(ocean or large lake):
• Water has a high specific heat, so Water has a high specific heat, so the ocean does NOT heat up or cool the ocean does NOT heat up or cool down easily, and therefore helps to down easily, and therefore helps to regulate temperatures of nearby regulate temperatures of nearby coastal areascoastal areas
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:3.3. Nearness to mountains:Nearness to mountains:
• Higher elevations have colder avg. Higher elevations have colder avg. temperatures, longer snowpack, etc.temperatures, longer snowpack, etc.
• Orographic effect: (rainshadow)Orographic effect: (rainshadow)– Windward side of mountains force air to rise, Windward side of mountains force air to rise,
expand, cool, and cause water vapor to expand, cool, and cause water vapor to condense, forming clouds and abundant condense, forming clouds and abundant rainfallrainfall
– Leeward side of mountains experience dry Leeward side of mountains experience dry conditions as air sinks…called the conditions as air sinks…called the “rainshadow” side.“rainshadow” side.
Orographic (Mountain) Effect:Orographic (Mountain) Effect:
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:
4.4. Wind Circulation Wind Circulation Patterns – caused by Patterns – caused by unequal heating of the unequal heating of the Earth, which creates Earth, which creates different temperature different temperature zones, which creates zones, which creates different pressure belts, different pressure belts, which forces the major which forces the major wind belts to occur, wind belts to occur, which determines major which determines major weather and climate weather and climate patternspatterns
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:
5.5. Ocean Circulation Patterns:Ocean Circulation Patterns:• Prevailing wind belts create mass Prevailing wind belts create mass
movements of ocean water (currents)movements of ocean water (currents)• Circular ocean currents are called “gyres”Circular ocean currents are called “gyres”• Ocean currents are also influenced by the Ocean currents are also influenced by the
Coriolis effect, and tend to circulate Coriolis effect, and tend to circulate clockwise in the N. hemisphere, and clockwise in the N. hemisphere, and counterclockwise in the S. hemispherecounterclockwise in the S. hemisphere
• Ocean currents are forced to move around Ocean currents are forced to move around major landmasses (continents and islands)major landmasses (continents and islands)
Earth’s Major Ocean CurrentsEarth’s Major Ocean Currents
Natural Physical Factors Affecting Natural Physical Factors Affecting Climate:Climate:
6.6. Ocean-Atmosphere InteractionsOcean-Atmosphere Interactions• Ocean interacts with the atmosphere to Ocean interacts with the atmosphere to
dramatically influence climate patterns dramatically influence climate patterns worldwideworldwide
• El Nino & La Nina can impact global climate El Nino & La Nina can impact global climate in any given yearin any given year
Long-Term Natural Factors Long-Term Natural Factors Affecting ClimateAffecting Climate• Paleoclimatology – the study of climate changes Paleoclimatology – the study of climate changes
over the history of the Earthover the history of the Earth• A variety of techniques and inferences are used A variety of techniques and inferences are used
to measure or infer atmospheric gas content, to measure or infer atmospheric gas content, temperatures, dust particles, life forms, etc.temperatures, dust particles, life forms, etc.
• Methods Used to Determine Past Climate:Methods Used to Determine Past Climate:1.1. Recorded Human Observations (only reliable for past Recorded Human Observations (only reliable for past
200 yrs.)200 yrs.)2.2. Ice Core DataIce Core Data3.3. Tree RingsTree Rings4.4. Soil SedimentsSoil Sediments5.5. Biological FossilsBiological Fossils
– Shells of aquatic organismsShells of aquatic organisms– CoralsCorals
Ice Core Data:Ice Core Data:
• Drilled from deep within the ground, ice cores Drilled from deep within the ground, ice cores can be used to measure increases and/or can be used to measure increases and/or decreases in snowfall over time as well as decreases in snowfall over time as well as changes in atmospheric gases as seen in changes in atmospheric gases as seen in trapped air bubbles, dust, and oxygen isotopes. trapped air bubbles, dust, and oxygen isotopes.
• Scientists drilling in the Greenland ice sheet Scientists drilling in the Greenland ice sheet have been able to piece together a climate have been able to piece together a climate record dating back approximately 110,000 yearsrecord dating back approximately 110,000 years
• Antarctic ice samples have yielded information Antarctic ice samples have yielded information as far back as 750,000 years. as far back as 750,000 years.
• Ice cores can provide vast amounts of Ice cores can provide vast amounts of information, including an annual record of information, including an annual record of temperature, precipitation, atmospheric temperature, precipitation, atmospheric composition, volcanic activity, and even wind composition, volcanic activity, and even wind patterns.patterns.
Ice Core Data:Ice Core Data:
• Specifically, COSpecifically, CO22 and CH and CH44 concentrations concentrations can be analyzed and used to infer past can be analyzed and used to infer past temperatures.temperatures.
• Thickness of ice layers also reflects Thickness of ice layers also reflects temperature and precipitation in the past.temperature and precipitation in the past.
• Atmospheric dust particles can also be Atmospheric dust particles can also be analyzed from ice cores.analyzed from ice cores.
Vostok Vostok Ice Ice
Core Core Data:Data:
Long-term natural influences on Long-term natural influences on climate…global changesclimate…global changes• There are several LONG-TERM changes that There are several LONG-TERM changes that
have influenced climate in a cyclic manner.have influenced climate in a cyclic manner.
• Milankovitch Cycles are the collective Milankovitch Cycles are the collective effect of changes in the Earth's movements effect of changes in the Earth's movements upon its climate, named after Serbian civil upon its climate, named after Serbian civil engineer and mathematician Milutin engineer and mathematician Milutin Milanković Milanković
• Variations in the Earth's eccentricity, axial Variations in the Earth's eccentricity, axial tilt, and precession comprise the three tilt, and precession comprise the three dominant cycles dominant cycles
Milankovitch Cycles: EccentricityMilankovitch Cycles: Eccentricity
• Eccentricity is, simply, the Eccentricity is, simply, the shape of the Earth's orbit shape of the Earth's orbit around the Sun. around the Sun.
• This constantly fluctuating, This constantly fluctuating, orbital shape ranges between orbital shape ranges between more and less elliptical (0 to 5% more and less elliptical (0 to 5% ellipticity) on a cycle of about ellipticity) on a cycle of about 100,000100,000 years. years.
• These oscillations, from more These oscillations, from more elliptic to less elliptic, are of elliptic to less elliptic, are of prime importance to glaciation prime importance to glaciation in that it alters the distance in that it alters the distance from the Earth to the Sun, thus from the Earth to the Sun, thus changing the distance the Sun's changing the distance the Sun's short wave radiation must short wave radiation must travel to reach Earth, travel to reach Earth, subsequently reducing or subsequently reducing or increasing the amount of increasing the amount of radiation received at the radiation received at the Earth's surface in different Earth's surface in different seasons. seasons.
Animated sequence
Milankovitch Cycles: Axial TiltMilankovitch Cycles: Axial Tilt
• Axial tilt is the inclination of the Earth's axis in relation Axial tilt is the inclination of the Earth's axis in relation to its plane of orbit around the Sun. to its plane of orbit around the Sun.
• Oscillations in the degree of Earth's axial tilt occur on a Oscillations in the degree of Earth's axial tilt occur on a periodicity of periodicity of 41,000 41,000 years from 21.5 to 24.5 degrees.years from 21.5 to 24.5 degrees.
• A larger tilt will result in warmer summers and colder A larger tilt will result in warmer summers and colder winters!winters!
Milankovitch Cycles: Precession Milankovitch Cycles: Precession (wobble)(wobble)• Precession is the Earth's slow wobble as it Precession is the Earth's slow wobble as it
spins on axis. This wobbling of the Earth on its spins on axis. This wobbling of the Earth on its axis can be likened to a top running down, and axis can be likened to a top running down, and beginning to wobble back and forth on its axis. beginning to wobble back and forth on its axis.
• The precession of Earth wobbles from pointing The precession of Earth wobbles from pointing at Polaris (North Star) to pointing at the star at Polaris (North Star) to pointing at the star Vega. Vega.
• When this shift to the axis pointing at Vega When this shift to the axis pointing at Vega occurs, Vega would then be considered the occurs, Vega would then be considered the North Star. This top-like wobble, or precession, North Star. This top-like wobble, or precession, has a periodicity of about has a periodicity of about 23,00023,000 years. years.
Milankovitch Cycles: Precession Milankovitch Cycles: Precession (wobble)(wobble)
Animated sequence
Milankovitch Cycles…overall Milankovitch Cycles…overall effect:effect:
Current Observations of Current Observations of ClimateClimate• Today, a wide variety of instruments has Today, a wide variety of instruments has
been deployed to continuously measure a been deployed to continuously measure a large number of climate factors including:large number of climate factors including:– Air temperatureAir temperature– Sea surface temperatureSea surface temperature
– Greenhouse Trace Gas concentrations (COGreenhouse Trace Gas concentrations (CO22, , CHCH44, O, O33, NO, NO, NO, NO22, etc., etc.
– Response of plants (budding times, size, etc.)Response of plants (budding times, size, etc.)– Response of animals (changes in range, Response of animals (changes in range,
timing of reproduction, etc.)timing of reproduction, etc.)
Introduction to Climate Introduction to Climate ChangeChange Evidence for Climate ChangeEvidence for Climate Change
14 warmest years since mid-1800s have 14 warmest years since mid-1800s have occurred since 1990occurred since 1990
Phenological spring in N. hemisphere Phenological spring in N. hemisphere now begins 6 days earliernow begins 6 days earlier
Warming is not due to natural causesWarming is not due to natural causes Human produced greenhouse gases are Human produced greenhouse gases are
most plausible explanationmost plausible explanation
Introduction to Climate Introduction to Climate Change: Mean Annual Change: Mean Annual Global Temperature 1960–Global Temperature 1960–20072007
Causes of Climate ChangeCauses of Climate Change
Greenhouse gas concentrations Greenhouse gas concentrations increasingincreasing
Causes of Climate ChangeCauses of Climate Change
Increased Increased concentration of concentration of COCO22 (right) (right) Burning fossil fuels Burning fossil fuels
in cars, industry in cars, industry and homesand homes
DeforestationDeforestation Burning of forestsBurning of forests
Greenhouse EffectGreenhouse Effect
Pollutants That Cool the Pollutants That Cool the AtmosphereAtmosphere
Atmospheric Aerosols Atmospheric Aerosols Both human and natural sourcesBoth human and natural sources Tiny particles that remain in troposphere Tiny particles that remain in troposphere
for weeks or monthsfor weeks or months Often contain sulfurOften contain sulfur
Complicates models of climate Complicates models of climate changechange
Climate ModelsClimate Models
Climate affected by:Climate affected by: winds, clouds, ocean currents, and albedo winds, clouds, ocean currents, and albedo
Used to explore past climate eventsUsed to explore past climate events Advanced models can project future Advanced models can project future
warming eventswarming events Models are only as good as the data Models are only as good as the data
and law used to program themand law used to program them They have limitationsThey have limitations
Climate ModelsClimate Models
Effects of Global Climate Effects of Global Climate ChangeChange Wildfire in CaliforniaWildfire in California
Effects of Global Climate Effects of Global Climate Change: Melting Ice and Change: Melting Ice and Rising Sea LevelsRising Sea Levels Sea level rise caused in 2 waysSea level rise caused in 2 ways
Thermal ExpansionThermal Expansion Melting of land iceMelting of land ice
Melting has positive feedbackMelting has positive feedback Increased melting decreases ice, which Increased melting decreases ice, which
decreases albedo leading to further decreases albedo leading to further warmingwarming
19519577
19919988
Glacier National ParkGlacier National Park
Melting Ice and Rising Sea Melting Ice and Rising Sea LevelsLevels
Case-In-Point Impacts in Case-In-Point Impacts in Fragile AreasFragile Areas
Eskimo Inuit liveEskimo Inuit livetraditional lifetraditional lifedictated by freezingdictated by freezingclimateclimate
Climate change isClimate change isaltering their existencealtering their existence Wildlife displacedWildlife displaced Reduced snow cover and shorter river ice Reduced snow cover and shorter river ice
seasonsseasons Thawing of permafrost (right)Thawing of permafrost (right)
Effects of Global Climate Effects of Global Climate Change: Changing Change: Changing Precipitation PatternsPrecipitation Patterns Some areas will get more water, Some areas will get more water,
some areas will have greater some areas will have greater droughtsdroughts
Effects of Global Climate Effects of Global Climate Change: Effects on OrganismsChange: Effects on Organisms
Zooplankton in parts of California Zooplankton in parts of California Current have decreased by 80% since Current have decreased by 80% since 19511951 Effecting entire food chainEffecting entire food chain
Decline in krill around AntarcticaDecline in krill around Antarctica Species have shifted their geographic Species have shifted their geographic
rangerange Migrating birds are returning to Migrating birds are returning to
summer homes earliersummer homes earlier
Effects on Organisms: Coral Effects on Organisms: Coral ReefsReefs Coral reefs can be bleached (right) Coral reefs can be bleached (right)
due to increase in water temperaturedue to increase in water temperature Affects coral symbiotes and makes them Affects coral symbiotes and makes them
more susceptible to diseasesmore susceptible to diseases
Effect on Organisms: Effect on Organisms: VegetationVegetation
Effect on Organisms: Effect on Organisms: VegetationVegetation
Effects on Human HealthEffects on Human Health Increased number of heat-related Increased number of heat-related
illnesses and deathsillnesses and deaths
Effects on AgricultureEffects on Agriculture Difficult to anticipateDifficult to anticipate
Productivity will increase in some areas and Productivity will increase in some areas and decrease in othersdecrease in others
Rise in sea level will inundate flood plains Rise in sea level will inundate flood plains and river valleys (lush farmland)and river valleys (lush farmland)
Effect on pests is unknownEffect on pests is unknown Warmer temperatures will decrease soil Warmer temperatures will decrease soil
moisture- requiring more irrigationmoisture- requiring more irrigation Location (i.e. elevation and altitude) where Location (i.e. elevation and altitude) where
certain crops can be grown may have to certain crops can be grown may have to changechange
International Implications of International Implications of Climate ChangeClimate Change Developed vs. Developed vs.
Developing Developing countriescountries Differing self-Differing self-
interestsinterests Differing Differing
ability to meet ability to meet the challenges the challenges of climate of climate changechange
Dealing with Global Climate Dealing with Global Climate ChangeChange
Two ways to manage climate changeTwo ways to manage climate change Mitigation: Limiting greenhouse gas Mitigation: Limiting greenhouse gas
emissions to moderate global climate emissions to moderate global climate changechange
Adaptation: Learning to live with Adaptation: Learning to live with environmental changes and societal environmental changes and societal consequences brought about by global consequences brought about by global climate change climate change
Relationship Between Relationship Between Mitigation and AdaptationMitigation and Adaptation
Dealing with Global Climate Dealing with Global Climate Change: MitigationChange: Mitigation
Locate/invent alternative fuels to Locate/invent alternative fuels to fossil fuelsfossil fuels
Increase efficiency of cars and trucksIncrease efficiency of cars and trucks Carbon Capture and StorageCarbon Capture and Storage Plant and Maintain trees to naturally Plant and Maintain trees to naturally
sequester carbonsequester carbon
Dealing with Global Climate Dealing with Global Climate Change: AdaptationChange: Adaptation Rising sea levels and coastal Rising sea levels and coastal
populationspopulations Move inlandMove inland Construct dikes and leveesConstruct dikes and levees
Adapt to shifting agricultural zonesAdapt to shifting agricultural zones NYC sewer lineNYC sewer line
International Efforts to International Efforts to Reduce Greenhouse Gas Reduce Greenhouse Gas EmissionEmission Kyoto ProtocolKyoto Protocol
Legally bindingLegally binding Provides operational rules on reducing Provides operational rules on reducing
greenhouse gasesgreenhouse gases US and Australia have not sign it - it will US and Australia have not sign it - it will
be difficult to implement without US be difficult to implement without US backingbacking
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