Lecture chapter 21 - global climate change

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 ChangeDealing with Global Climate Change

Climate Change-Climate Change-
Mean Annual Global Temperature 1960-2005Mean Annual Global Temperature 1960-2005

Climate Change TerminologyClimate Change Terminology
o Greenhouse GasGreenhouse Gas
• Gas that absorbs infrared radiationGas that absorbs infrared radiation
• Ex: Carbon dioxide, methane, nitrous oxide, chlorofluorocarbonsEx: Carbon dioxide, methane, nitrous oxide, chlorofluorocarbons
and tropospheric ozoneand tropospheric ozone
o Positive FeedbackPositive Feedback
• Change in some condition triggers a response that intensifies theChange in some condition triggers a response that intensifies the
changed conditionchanged condition
o Infrared RadiationInfrared Radiation
• Radiation that has a wavelength that is longer than that of visibleRadiation that has a wavelength that is longer than that of visible
light, but shorter than that of radio waveslight, but shorter than that of radio waves
o Greenhouse EffectGreenhouse Effect
• Increase of heat in a system where energy enters (often as light), isIncrease of heat in a system where energy enters (often as light), is
absorbed as heat, and released sometime laterabsorbed as heat, and released sometime later

Climate ChangeClimate Change
o Evidence for Climate ChangeEvidence for Climate Change
• 11 of the 12 years between 1995 and 2006 were among11 of the 12 years between 1995 and 2006 were among
the twelve warmest years since the mid-1800sthe twelve warmest years since the mid-1800s
• Phenological spring in N. hemisphere now comes 6 daysPhenological spring in N. hemisphere now comes 6 days
earlierearlier
o Warming is not due to natural causesWarming is not due to natural causes
• Human produced greenhouse gases are most plausibleHuman produced greenhouse gases are most plausible
explanationexplanation

CausesCauses
o Greenhouse gas concentrations increasingGreenhouse gas concentrations increasing

o Increased concentrationIncreased concentration
of COof CO22 (right)(right)
• Burning fossil fuels inBurning fossil fuels in
cars, industry and homescars, industry and homes
• DeforestationDeforestation
• Burning of forestsBurning of forests
CausesCauses

Greenhouse EffectGreenhouse Effect

Other Pollutants Cool the AtmosphereOther Pollutants Cool the Atmosphere
o Atmospheric Aerosols tend to cool the atmosphereAtmospheric Aerosols tend to cool the atmosphere
• Both human and natural sourcesBoth human and natural sources
• Tiny particles that remain in troposphere for weeks orTiny particles that remain in troposphere for weeks or
monthsmonths
• Contain many chemicals, but often contain sulfurContain many chemicals, but often contain sulfur
o Complicates models of climate changeComplicates models of climate change

Climate ModelsClimate Models
o Climate affected by:Climate affected by:
• winds, clouds, ocean currents,winds, clouds, ocean currents,
and albedoand albedo
o Used to explore past climateUsed to explore past climate
eventsevents
o Advanced models can projectAdvanced models can project
future warming eventsfuture warming events
o Models are only as good as theModels are only as good as the
data and law used to programdata and law used to program
themthem
• They have limitationsThey have limitations

Effects of Global Climate ChangeEffects of Global Climate Change
o Ocean as COOcean as CO22 sink - excess COsink - excess CO22 is starting to harmis starting to harm
ocean lifeocean life

Effects of Global Climate Change- Melting IceEffects of Global Climate Change- Melting Ice
and Rising Sea Levelsand 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 polesRetreat of glacier and thinning of ice at the poles
o Melting has positive feedbackMelting has positive feedback
• Increased melting decreases ice, which decreases albedoIncreased melting decreases ice, which decreases albedo
leading to further warmingleading to further warming

Melting Ice and Rising Sea LevelsMelting Ice and Rising Sea Levels
19571957
19981998

Case-In-Point Impacts in Fragile AreasCase-In-Point Impacts in Fragile Areas
o Eskimo Inuit live traditional lifeEskimo Inuit live traditional life
dictated by freezing climatedictated by freezing climate
o Climate change is altering theirClimate change is altering their
existenceexistence
• Wildlife are smaller or displacedWildlife are smaller or displaced
• Reduced snow cover and shorterReduced snow cover and shorter
river ice seasonsriver ice seasons
• Thawing of permafrost (right)Thawing of permafrost (right)

o Some areas will get more water, some areas willSome areas will get more water, some areas will
have greater droughtshave greater droughts
• Ex: Hurricanes will likely get strongerEx: Hurricanes will likely get stronger
Effects of Global Climate Change-Effects of Global Climate Change-
Changing Precipitation PatternsChanging Precipitation Patterns

o Zooplankton in parts of California Current haveZooplankton in parts of California Current have
decreased by 80% since 1951decreased 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 rangeSpecies have shifted their geographic range
o Migrating birds are returning to summer homesMigrating birds are returning to summer homes
earlierearlier
• Food is not available at this timeFood is not available at this time
Effects of Global Climate Change-Effects of Global Climate Change-
Effects on OrganismsEffects on Organisms

Effects on Organisms - Coral ReefsEffects on Organisms - Coral Reefs
o Coral reefs can be bleached (right) due to increaseCoral reefs can be bleached (right) due to increase
in water temperaturein water temperature
• Affects coral symbiotes and makes them moreAffects coral symbiotes and makes them more
susceptible to diseases to which they would otherwise besusceptible to diseases to which they would otherwise be
immuneimmune

Effect on Organisms - VegetationEffect on Organisms - Vegetation
Beech Tree RangeBeech Tree Range

Effects on Human HealthEffects on Human Health
o Increased number of heat-related illnesses andIncreased number of heat-related illnesses and
deathsdeaths

Effects on AgricultureEffects on Agriculture
o Difficult to anticipateDifficult to anticipate
• Productivity will increase in some areas and decrease in othersProductivity will increase in some areas and decrease in others
o Rise in sea level will inundate flood plains and river valleysRise in sea level will inundate flood plains and river valleys
(lush farmland)(lush farmland)
o Effect on pests is unknownEffect on pests is unknown
o Warmer temperatures will decrease soil moisture- requiringWarmer temperatures will decrease soil moisture- requiring
more irrigationmore irrigation
o Location (i.e. elevation and altitude) where certain crops canLocation (i.e. elevation and altitude) where certain crops can
be grown may have to changebe grown may have to change

International ImplicationsInternational Implications
of Climate Changeof Climate Change
o Developed vs.Developed vs.
Developing countriesDeveloping countries
• Differing self-interestsDiffering self-interests
• Differing ability to meetDiffering ability to meet
the challenges of climatethe challenges of climate
changechange

Dealing with Global Climate ChangeDealing with Global Climate Change
o To avoid the worst of climate change, COTo avoid the worst of climate change, CO22 levelslevels
must be stabilized at 550ppmmust be stabilized at 550ppm
• 50% higher than current levels50% higher than current levels
o Two ways to attempt to manage climate changeTwo ways to attempt to manage climate change
• MitigationMitigation
•
Focuses on limiting greenhouse gas emissions to moderateFocuses on limiting greenhouse gas emissions to moderate
global climate changeglobal climate change
• AdaptationAdaptation
•
Focuses on learning to live with to the environmental changesFocuses on learning to live with to the environmental changes
and societal consequences brought about by global climateand societal consequences brought about by global climate
changechange

Dealing with Global Climate Change-Dealing with Global Climate Change-
Relationship Between Mitigation andRelationship Between Mitigation and
AdaptationAdaptation

Dealing with Global ClimateDealing with Global Climate
Change- MitigationChange- Mitigation
o Locate/invent alternative fuels to fossil fuelsLocate/invent alternative fuels to fossil fuels
o Increase efficiency of cars and trucksIncrease efficiency of cars and trucks
o Sequestering carbon before it is emittedSequestering carbon before it is emitted
o Plant and Maintain trees to naturally sequesterPlant and Maintain trees to naturally sequester
carboncarbon

Dealing with Global Climate Change-Dealing with Global Climate Change-
AdaptationAdaptation
o Rising sea levels andRising sea levels and
coastal populationscoastal populations
• Move inlandMove inland
• Construct dikesConstruct dikes
and leveesand levees
o Adapt to shiftingAdapt 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 ozone
o UV lightUV light
o Chemical processesChemical processes
o Environmental effectsEnvironmental effects
o SolutionsSolutions

AtmosphereAtmosphere
o Stratospheric ozoneStratospheric ozone
o 20-30 km altitude20-30 km altitude
o 19 mi at equator, 9 mi at the poles19 mi at equator, 9 mi at the poles
o 400 ppb400 ppb

Ozone shieldOzone shield
o 99% of all UV is absorbed99% of all UV is absorbed
(UVC and most UVB)(UVC and most UVB)
o UVA is not affected byUVA is not affected by
ozoneozone

Production of ozoneProduction of ozone

Measurement of OzoneMeasurement of Ozone
o Dobson units: 1 ppbDobson units: 1 ppb
ozoneozone
o Survey began in 1957 overSurvey began in 1957 over
the Antarcticthe Antarctic
o Taken in October,Taken in October,
springtimespringtime
o 1957-1970: 300 DU1957-1970: 300 DU
o 150 DU by 1986150 DU by 1986

Ozone and CFC’sOzone and CFC’s
o Molina and Rowland in 1974Molina and Rowland in 1974
o CFC’s are stableCFC’s are stable
o Long residence in lowerLong residence in lower
atmosphereatmosphere
o UV radiation breaks down CFCUV radiation breaks down CFC
and releases Cland releases Cl
o Cl reacts with OCl reacts with O33
o Increase UVB at the surfaceIncrease UVB at the surface

Formation and destruction of ozoneFormation and destruction of ozone

Polar Stratospheric cloudsPolar Stratospheric clouds
o Polar winter formationPolar winter formation
o Have polar vortexHave polar vortex
o Isolated air massIsolated air mass
o Nitrogen oxides held inNitrogen oxides held in
clouds as nitric acidclouds as nitric acid
o NONO33 particles grow and fallparticles grow and fall
outout
o Facilitates ozone depletingFacilitates ozone depleting
reactionsreactions

Polar vortexPolar vortex
In Springtime, sunlight
Returns
No nitrate to form CloNO2

Environmental effectsEnvironmental effects
o UV damage to DNAUV damage to DNA
o Skin cancerSkin cancer
o CataractsCataracts
o Suppression of immune systemSuppression of immune system
o Ecosystem:Ecosystem:
o Primary producersPrimary producers
o Food chainsFood chains
o Development in aquatic larvaDevelopment in aquatic larva

Managing ozone depletionManaging ozone depletion
o Montreal protocol, Sept 1987–Montreal protocol, Sept 1987–
Production of CFC eliminationProduction of CFC elimination
o Economic gapEconomic gap
o Replacements: HFC and HCFCReplacements: HFC and HCFC
o Shorter lifetime, less reactiveShorter lifetime, less reactive
o Collection and reuse (noCollection and reuse (no
venting)venting)
o Expensive replacementsExpensive replacements

Climate ChangeClimate Change
o Climate SwingsClimate Swings
o Greenhouse gasesGreenhouse gases
o EvidenceEvidence
o PredictionsPredictions
o ControlControl

Historic Climate shiftsHistoric Climate shifts
o Milankovitch cycles: shifts in earth‘s orbit and tiltMilankovitch cycles: shifts in earth‘s orbit and tilt
o Volcanic activity: Mt. TobaVolcanic activity: Mt. Toba

El Nino/Southern OscillationEl Nino/Southern Oscillation
o Trade winds keep warm water inTrade winds keep warm water in
W. Pacific. La NinaW. Pacific. La Nina
o El Nino: Shift in tropicalEl Nino: Shift in tropical
depressiondepression
o Northern Jet stream splits changesNorthern Jet stream splits changes
rainfall patternsrainfall patterns
o Pacific decadal oscillation: warmPacific decadal oscillation: warm
water in northern pacific moveswater in northern pacific moves
back and forth.back and forth.
o Cool water in north help AlsakaCool water in north help Alsaka
salmon runs, warm off coast andsalmon runs, warm off coast and
then switches.then switches.

Human ActivitiesHuman Activities
o IndustrializationIndustrialization
o COCO22 increased 31%, CHincreased 31%, CH44 inc 151%, Ninc 151%, N22O inc 17% over since pre-O inc 17% over since pre-
industrial times.industrial times.
o 40% of excess CO40% of excess CO22 absorbed by oceansabsorbed by oceans
o Methane a big problemMethane a big problem

Evidence of Climate ChangeEvidence of Climate Change
o Avg global temperature has climbed 0.6Avg global temperature has climbed 0.6oo
C over last centuryC over last century
o Arctic sea ice is 40% thinner, Antarctic glaciers are retreating 50m/yr.Arctic sea ice is 40% thinner, Antarctic glaciers are retreating 50m/yr.
o Alpine glaciers are retreatingAlpine glaciers are retreating
o Ocean acidificationOcean acidification
o Sea level has risenSea level has risen
o Changes in animal behavior, breeding cyclesChanges in animal behavior, breeding cycles
o Storm frequency and intensity are increasingStorm frequency and intensity are increasing

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

Lecture chapter 21 - global climate change

ConsequencesConsequences
Arctic sea ice Alpine glaciers

PredictionsPredictions
Sugar maple range
Predicted warming with doubling of
CO2

Reduction of Carbon EmissionsReduction of Carbon Emissions
o Burn less fossil fuel: Turn down your thermostatBurn less fossil fuel: Turn down your thermostat
o Plant Trees for shade and COPlant Trees for shade and CO22 uptakeuptake
o Insulate your houseInsulate your house
o Replace old appliancesReplace old appliances
o Use compact fluorescence light bulbsUse compact fluorescence light bulbs
o Use renewable energyUse renewable energy

Lecture chapter 21 - global climate change

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Lecture chapter 21 - global climate change