Chapter #21

Global Climate Change

OverviewOverview

o Introduction to Climate ChangeIntroduction to Climate Change• Causes of Global Climate ChangeCauses of Global Climate Change

o 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

o Dealing with Global Climate Dealing with Global Climate ChangeChange

Climate Change-Climate Change-Mean Annual Global Temperature 1960-Mean Annual Global Temperature 1960-

20052005

Climate Change Climate Change TerminologyTerminology

o Greenhouse GasGreenhouse Gas• Gas that absorbs infrared radiationGas that absorbs infrared radiation• Ex: Carbon dioxide, methane, nitrous oxide, Ex: Carbon dioxide, methane, nitrous oxide,

chlorofluorocarbons and tropospheric ozonechlorofluorocarbons and tropospheric ozoneo Positive FeedbackPositive Feedback

• Change in some condition triggers a response that Change in some condition triggers a response that intensifies the changed condition intensifies the changed condition

o Infrared RadiationInfrared Radiation• Radiation that has a wavelength that is longer than Radiation that has a wavelength that is longer than

that of visible light, but shorter than that of radio that of visible light, but shorter than that of radio waves waves

o 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

Climate ChangeClimate Changeo Evidence for Climate ChangeEvidence for Climate Change

• 11 of the 12 years between 1995 and 2006 11 of the 12 years between 1995 and 2006 were among the twelve warmest years were among the twelve warmest years since the mid-1800s since the mid-1800s

• Phenological spring in N. hemisphere now Phenological spring in N. hemisphere now comes 6 days earliercomes 6 days earlier

o 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

CausesCauseso Greenhouse gas concentrations Greenhouse gas concentrations

increasingincreasing

o Increased Increased concentration of concentration of COCO22 (right) (right)• Burning fossil Burning fossil

fuels in cars, fuels in cars, industry and industry and homeshomes

• DeforestationDeforestation• Burning of forestsBurning of forests

CausesCauses

Greenhouse EffectGreenhouse Effect

Other Pollutants Cool the Other Pollutants Cool the AtmosphereAtmosphere

o Atmospheric Aerosols tend to cool the Atmospheric Aerosols tend to cool the atmosphereatmosphere• 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• Contain many chemicals, but often contain Contain many chemicals, but often contain

sulfursulfuro Complicates models of climate changeComplicates models of climate change

Climate ModelsClimate Modelso Climate affected by:Climate affected by:

• winds, clouds, ocean winds, clouds, ocean currents, and albedo currents, and albedo

o Used to explore past Used to explore past climate eventsclimate events

o Advanced models can Advanced models can project future warming project future warming eventsevents

o Models are only as good Models are only as good as the data and law as the data and law used to program themused to program them

• They have limitationsThey have limitations

Climate ModelsClimate Models

Effects of Global Climate Effects of Global Climate ChangeChange

o Ocean as COOcean as CO22 sink - excess CO sink - excess CO22 is starting to is starting to harm ocean lifeharm ocean life

Effects of Global Climate Change- Effects of Global Climate Change- Melting Ice and Rising Sea LevelsMelting Ice and Rising Sea Levels

o Sea level rise caused in 2 waysSea level rise caused in 2 ways• Thermal ExpansionThermal Expansion

• Water expands as it warmsWater expands as it warms• Melting of land iceMelting of land ice

• Retreat of glacier and thinning of ice at the Retreat of glacier and thinning of ice at the polespoles

o 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

Melting Ice and Rising Sea Melting Ice and Rising Sea LevelsLevels

19519577

19919988

Case-In-Point Impacts in Fragile Case-In-Point Impacts in Fragile AreasAreas

o Eskimo Inuit live Eskimo Inuit live traditional life dictated traditional life dictated by freezing climateby freezing climate

o Climate change is Climate change is altering their existencealtering their existence• Wildlife are smaller or Wildlife are smaller or

displaceddisplaced• Reduced snow cover and Reduced snow cover and

shorter river ice seasonsshorter river ice seasons• Thawing of permafrost Thawing of permafrost

(right)(right)

o Some areas will get more water, some Some areas will get more water, some areas will have greater droughtsareas will have greater droughts• Ex: Hurricanes will likely get strongerEx: Hurricanes will likely get stronger

Effects of Global Climate Effects of Global Climate Change- Changing Change- Changing

Precipitation PatternsPrecipitation Patterns

o Zooplankton in parts of California Current Zooplankton in parts of California Current have decreased by 80% since 1951have decreased by 80% since 1951• Effecting entire food chainEffecting entire food chain

o Decline in krill around AntarcticaDecline in krill around Antarctica• Caused decrease in penguin populationsCaused decrease in penguin populations

o Species have shifted their geographic Species have shifted their geographic rangerange

o Migrating birds are returning to summer Migrating birds are returning to summer homes earlierhomes earlier• Food is not available at this timeFood is not available at this time

Effects of Global Climate Effects of Global Climate Change- Effects on Change- Effects on

OrganismsOrganisms

Effects on Organisms - Coral Effects on Organisms - Coral ReefsReefs

o Coral reefs can be bleached (right) due Coral reefs can be bleached (right) due to increase in water temperatureto increase in water temperature• Affects coral symbiotes and makes them Affects coral symbiotes and makes them

more susceptible to diseases to which they more susceptible to diseases to which they would otherwise be immunewould otherwise be immune

Effect on Organisms - VegetationEffect on Organisms - VegetationBeech Tree RangeBeech Tree Range

Effects on Human HealthEffects on Human Health

o Increased number of heat-related Increased number of heat-related illnesses and deathsillnesses and deaths

Effects on AgricultureEffects on Agriculture

o Difficult to anticipateDifficult to anticipate• Productivity will increase in some areas and Productivity will increase in some areas and

decrease in othersdecrease in otherso 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)o Effect on pests is unknownEffect on pests is unknowno Warmer temperatures will decrease soil Warmer temperatures will decrease soil

moisture- requiring more irrigationmoisture- requiring more irrigationo 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 ImplicationsInternational Implicationsof Climate Changeof Climate Change

o Developed vs. Developed vs. Developing Developing countriescountries• Differing self-Differing self-

interestsinterests• Differing ability to Differing ability to

meet the challenges meet the challenges of climate changeof climate change

Dealing with Global Climate Dealing with Global Climate ChangeChange

o To avoid the worst of climate change, To avoid the worst of climate change, COCO22 levels must be stabilized at 550ppm levels must be stabilized at 550ppm• 50% higher than current levels50% higher than current levels

o Two ways to attempt to manage climate Two ways to attempt to manage climate changechange• MitigationMitigation

• Focuses on limiting greenhouse gas emissions to Focuses on limiting greenhouse gas emissions to moderate global climate changemoderate global climate change

• AdaptationAdaptation• Focuses on learning to live with to the Focuses on learning to live with to the

environmental changes and societal consequences environmental changes and societal consequences brought about by global climate change brought about by global climate change

Dealing with Global Climate Dealing with Global Climate Change- Relationship Between Change- Relationship Between

Mitigation and AdaptationMitigation and Adaptation

Dealing with Global Climate Dealing with Global Climate Change- MitigationChange- Mitigation

o Locate/invent alternative fuels to fossil Locate/invent alternative fuels to fossil fuelsfuels

o Increase efficiency of cars and trucksIncrease efficiency of cars and truckso Sequestering carbon before it is Sequestering carbon before it is

emittedemittedo 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

o Rising sea levels Rising sea levels and coastal and coastal populationspopulations• Move inlandMove inland• Construct Construct

dikes and dikes and leveeslevees

o Adapt to shifting Adapt to shifting agricultural zonesagricultural zones

o NYC sewer lineNYC sewer line

“There were rumors of

unfathomable things,

and because we could not fathom them we failed to

believe them, until we had no choice it was too late.”

Ozone DepletionOzone Depletion

o Stratospheric ozoneStratospheric ozoneo UV lightUV lighto Chemical processesChemical processeso Environmental Environmental

effectseffectso SolutionsSolutions

AtmosphereAtmosphere

o Stratospheric ozoneStratospheric ozoneo 20-30 km altitude20-30 km altitudeo 19 mi at equator, 9 mi at the poles19 mi at equator, 9 mi at the poleso 400 ppb400 ppb

Ozone shieldOzone shield

o 99% of all UV is 99% of all UV is absorbed (UVC and absorbed (UVC and most UVB)most UVB)

o UVA is not affected UVA is not affected by ozoneby ozone

Production of ozoneProduction of ozone

Measurement of OzoneMeasurement of Ozone

o Dobson units: 1 ppb Dobson units: 1 ppb ozoneozone

o Survey began in Survey began in 1957 over the 1957 over the AntarcticAntarctic

o Taken in October, Taken in October, springtimespringtime

o 1957-1970: 300 DU1957-1970: 300 DUo 150 DU by 1986150 DU by 1986

Ozone and CFC’sOzone and CFC’so Molina and Rowland in Molina and Rowland in

19741974o CFC’s are stableCFC’s are stableo Long residence in lower Long residence in lower

atmosphereatmosphereo UV radiation breaks UV radiation breaks

down CFC and releases down CFC and releases Cl Cl

o Cl reacts with OCl reacts with O3 3

o Increase UVB at the Increase UVB at the surfacesurface

Formation and destruction of ozoneFormation and destruction of ozone

EmissionsEmissions

UsageUsage2003

Ozone HoleOzone Hole

Polar Stratospheric cloudsPolar Stratospheric cloudso Polar winter Polar winter

formationformationo Have polar vortexHave polar vortexo Isolated air massIsolated air masso Nitrogen oxides held Nitrogen oxides held

in clouds as nitric acidin clouds as nitric acido NONO33 particles grow particles grow

and fall outand fall outo Facilitates ozone Facilitates ozone

depleting reactionsdepleting reactions

Polar vortexPolar vortex

In Springtime, sunlightReturnsNo nitrate to form CloNO2

Environmental effectsEnvironmental effectso UV damage to DNAUV damage to DNAo Skin cancerSkin cancero CataractsCataractso Suppression of immune Suppression of immune

systemsystemo Ecosystem:Ecosystem:o Primary producersPrimary producerso Food chainsFood chainso Development in aquatic Development in aquatic

larvalarva

Managing ozone depletionManaging ozone depletiono Montreal protocol, Sept Montreal protocol, Sept

1987– Production of 1987– Production of CFC eliminationCFC elimination

o Economic gapEconomic gapo Replacements: HFC and Replacements: HFC and

HCFCHCFCo Shorter lifetime, less Shorter lifetime, less

reactivereactiveo Collection and reuse (no Collection and reuse (no

venting)venting)o Expensive replacementsExpensive replacements

Climate ChangeClimate Changeo Climate SwingsClimate Swingso Greenhouse gasesGreenhouse gaseso EvidenceEvidenceo PredictionsPredictionso ControlControl

Historic Climate shiftsHistoric Climate shifts

o Milankovitch cycles: shifts in earth‘s orbit Milankovitch cycles: shifts in earth‘s orbit and tiltand tilt

o Volcanic activity: Mt. TobaVolcanic activity: Mt. Toba

El Nino/Southern OscillationEl Nino/Southern Oscillationo Trade winds keep warm Trade winds keep warm

water in W. Pacific. La water in W. Pacific. La NinaNina

o El Nino: Shift in tropical El Nino: Shift in tropical depressiondepression

o Northern Jet stream splits Northern Jet stream splits changes rainfall patternschanges rainfall patterns

o Pacific decadal oscillation: Pacific decadal oscillation: warm water in northern warm water in northern pacific moves back and pacific moves back and forth.forth.

o Cool water in north help Cool water in north help Alsaka salmon runs, warm Alsaka salmon runs, warm off coast and then off coast and then switches.switches.

Human ActivitiesHuman Activities

o IndustrializationIndustrializationo COCO22 increased 31%, CH increased 31%, CH44 inc 151%, N inc 151%, N22O inc 17% over O inc 17% over

since pre-industrial times.since pre-industrial times.o 40% of excess CO40% of excess CO22 absorbed by oceans absorbed by oceanso Methane a big problemMethane a big problem

Evidence of Climate ChangeEvidence of Climate Changeo Avg global temperature has climbed 0.6Avg global temperature has climbed 0.6ooC over last centuryC over last centuryo Arctic sea ice is 40% thinner, Antarctic glaciers are retreating Arctic sea ice is 40% thinner, Antarctic glaciers are retreating

50m/yr.50m/yr.o Alpine glaciers are retreatingAlpine glaciers are retreatingo Ocean acidificationOcean acidificationo Sea level has risenSea level has riseno Changes in animal behavior, breeding cyclesChanges in animal behavior, breeding cycleso Storm frequency and intensity are increasingStorm frequency and intensity are increasing

Larsen B ice shelf-- AntarcticaLarsen B ice shelf-- Antarctica

ConsequencesConsequencesArctic sea ice Alpine glaciers

PredictionsPredictions

Sugar maple range

Predicted warming with doubling ofCO2

Controls Controls

Reduction of Carbon EmissionsReduction of Carbon Emissions

o Burn less fossil fuel: Turn down your Burn less fossil fuel: Turn down your thermostatthermostat

o Plant Trees for shade and COPlant Trees for shade and CO22 uptake uptakeo Insulate your houseInsulate your houseo Replace old appliancesReplace old applianceso Use compact fluorescence light bulbsUse compact fluorescence light bulbso Use renewable energyUse renewable energy