Chapter 20 Climate Change & Ozone Loss. Essential Question #1 How have the Earth’s temperature and climate changed in the past & how are greenhouse gases

Chapter 20Chapter 20

Climate Change & Climate Change & Ozone LossOzone Loss

Essential Question #1Essential Question #1

How have the Earth’s How have the Earth’s temperature and climate temperature and climate

changed in the past & changed in the past & how are greenhouse how are greenhouse

gases involved?gases involved?

Past Climate ChangesPast Climate Changes

Troposphere has experienced prolonged Troposphere has experienced prolonged periods of:periods of:

• Global Warming (interglacial periods) &Global Warming (interglacial periods) &• Global Cooling (glacial periods)Global Cooling (glacial periods)

• For the last 12,000 years we have been in an For the last 12,000 years we have been in an interglacial periodinterglacial period

Fairly stable for past 1000 yrs, begun rising during Fairly stable for past 1000 yrs, begun rising during last centurylast century

Thousands of years ago

Ave

rag

e su

rfac

e te

mp

erat

ure

(°C

)

900 800 700 600 500 400 300 200 100 Present9

10

11

12

13

14

15

16

17

Fig. 16-2a, p. 369

Average Global Temperature Average Global Temperature over the Past 900,000 Yearsover the Past 900,000 Years

Fig. 20-2d, p. 465

Tem

pera

ture

ch

an

ge (

C°)

Temperature change over past 1,000 years

Year

Fig. 20-2b, p. 465

Ave

rag

e su

rfac

e te

mp

erat

ure

(°C

)

Year

Average temperature over past 130 years

How do we know?How do we know? Past temperature Past temperature

measurements come measurements come from analyzing:from analyzing:

• Radioisotopes in rocks Radioisotopes in rocks and fossilsand fossils

• Ocean sedimentsOcean sediments

• Tree Rings & Historical Tree Rings & Historical RecordsRecords

• Ice cores from ancient Ice cores from ancient glaciers [COglaciers [CO22 & CH & CH44]]

How Do We Know What How Do We Know What Temperatures Were in the Past?Temperatures Were in the Past?

Ice Cores Teach Us Ice Cores Teach Us About:About:

Troposphere Troposphere CompositionComposition..

Temperature TrendsTemperature Trends..

Greenhouse Gas Greenhouse Gas ConcentrationsConcentrations..

SolarSolar, , SnowfallSnowfall, and , and Forest Fire activityForest Fire activity..

Changes in [CO2] levels correlate Changes in [CO2] levels correlate closely with avg. global temp. for the closely with avg. global temp. for the

past 160,000 years!past 160,000 years!

In 2005, an ice core In 2005, an ice core showed that COshowed that CO22

levels in the levels in the troposphere are the troposphere are the highest they have highest they have been in 650,000 been in 650,000 years.years.

3 Major Factors 3 Major Factors Shaping Earth’s ClimateShaping Earth’s Climate

Solar energySolar energy

Greenhouse EffectGreenhouse Effect

OceansOceans

The Natural Greenhouse EffectThe Natural Greenhouse Effect

4 Natural Greenhouse Gases4 Natural Greenhouse Gases• Water vapor (H20) Water vapor (H20) • Carbon Dioxide (CO2)*Carbon Dioxide (CO2)*• Methane (CH4)*Methane (CH4)*• Nitrous Oxide (N2O)Nitrous Oxide (N2O)

Absorb heat Absorb heat (infrared (infrared radiation) radiation)

reflected from reflected from Earth’s surface & Earth’s surface &

warm the warm the tropospheretroposphere

Human Input of Human Input of Greenhouse GasesGreenhouse Gases

Burning fossil fuels Burning fossil fuels Adds CO2 & CH4Adds CO2 & CH4

Clearing & Burning Clearing & Burning Forests Forests Adds CO2 & N20Adds CO2 & N20

Planting Rice & Using Planting Rice & Using Inorganic Fertilizers Inorganic Fertilizers Adds N20Adds N20

Figure 20-5Figure 20-5

Global CO2 EmissionsGlobal CO2 EmissionsChina & the U.S. are the largest emitters of CO2China & the U.S. are the largest emitters of CO2

Future of CO2 EmissionsFuture of CO2 Emissions

Average concentration on CO2 rose from Average concentration on CO2 rose from ~280 ppm ~280 ppm at at start of Industrial Revolution to start of Industrial Revolution to 389 ppm 389 ppm in 2010.in 2010.

If emissions continue at their current rate, levels could If emissions continue at their current rate, levels could rise to rise to 560 ppm 560 ppm by 2050 and by 2050 and 1,390 ppm 1,390 ppm by 2100. by 2100.

• Likely to cause major ecological and economic disruption.Likely to cause major ecological and economic disruption.

Climate models indicate that Climate models indicate that 450 ppm 450 ppm may be a may be a tipping point, that could set into motion large-scale tipping point, that could set into motion large-scale climate changes for hundreds to thousands of years.climate changes for hundreds to thousands of years.

Essential Question #2 & 3Essential Question #2 & 3What signs point to a warming What signs point to a warming

troposphere?troposphere?

How is the earth’s temperature How is the earth’s temperature projected to change in the future projected to change in the future

and why should we care?and why should we care?

Global Warming & Climate Global Warming & Climate ChangeChange

Global WarmingGlobal Warming• Refers to temperature Refers to temperature

increases in the increases in the troposphere, which in turn troposphere, which in turn can cause climate changecan cause climate change

Global Climate ChangeGlobal Climate Change• A broader term referring to A broader term referring to

changes in any aspects of changes in any aspects of the earth’s climate, including the earth’s climate, including temperature, precipitation, & temperature, precipitation, & storm intensity patternsstorm intensity patterns

Findings from the IPCCFindings from the IPCC

Intergovernmental Panel on Intergovernmental Panel on Climate ChangeClimate Change, IPCC , IPCC

• Formed by the United Nations & World Formed by the United Nations & World Meteorological Organization in 1988Meteorological Organization in 1988

• A network of over 2,500 climate scientists and scientists in A network of over 2,500 climate scientists and scientists in related disciplines from more than 130 countriesrelated disciplines from more than 130 countries

• One of the longest and most thorough studies One of the longest and most thorough studies in the history of science in the history of science

• Based on over 29,000 sets of data and Based on over 29,000 sets of data and

18,000 peer reviewed publications18,000 peer reviewed publications

Signs that Troposphere is WarmingSigns that Troposphere is Warming

According to the 2001 & 2007 IPCC Reports:According to the 2001 & 2007 IPCC Reports:

• Earth’s lower atmosphere has warmed approx. 1° F Earth’s lower atmosphere has warmed approx. 1° F (0.6° C) since 1980, due primarily to increased (0.6° C) since 1980, due primarily to increased concentrations of greenhouse gassesconcentrations of greenhouse gasses

CO2, CH4 and N2O have risen sharply since 1861 (U.S. National CO2, CH4 and N2O have risen sharply since 1861 (U.S. National Academy of Sciences)Academy of Sciences)

• Human activities played a major role in this Human activities played a major role in this warming, especially due to burning of fossil fuels & warming, especially due to burning of fossil fuels & deforestationdeforestation

Greenhouse gas emissions from human activities rose 70% Greenhouse gas emissions from human activities rose 70% between 1970 and 2009between 1970 and 2009

IPCC ReportIPCC Report 20th century was the hottest century in 1000 years20th century was the hottest century in 1000 years

The first decade of this century (2000-2009) was the The first decade of this century (2000-2009) was the warmest decade since 1881warmest decade since 1881

Average surface temperature has risen by ~1.3° F betw. Average surface temperature has risen by ~1.3° F betw. 1906 & 20051906 & 2005

Glaciers and sea ice are melting and shrinking which Glaciers and sea ice are melting and shrinking which exposes more dark land causing further warming exposes more dark land causing further warming

Ice MeltIce Melt

IPCC ReportIPCC Report

Permafrost is melting Permafrost is melting • releases COreleases CO22 and CH and CH44

Sea Levels are RisingSea Levels are Rising• 7 in (19cm) last century7 in (19cm) last century

IPCC Mathematical ModelsIPCC Mathematical Models

Strong evidence to support that the Strong evidence to support that the warming observed in the “last 50 years warming observed in the “last 50 years is attributable to human activities” is attributable to human activities”

90-99% probability that mean surface 90-99% probability that mean surface temperature will increase by 4.5° – 9.7° F temperature will increase by 4.5° – 9.7° F between 2000 and 2100 between 2000 and 2100

• Other scientific groups have reached similar Other scientific groups have reached similar conclusionsconclusions

IPCC: Future of Climate?IPCC: Future of Climate?

If greenhouse gas If greenhouse gas concentrations concentrations continue to increase, continue to increase, the Earth is likely to the Earth is likely to experience rapid experience rapid atmospheric warming atmospheric warming and climate disruption and climate disruption during this centuryduring this century

This would cause This would cause ecological, economic ecological, economic and social disruptionand social disruption

Why should we be concerned?Why should we be concerned? Humans & biodiversity cannot adapt to Humans & biodiversity cannot adapt to

rapid changesrapid changes

Alter water availabilityAlter water availability

Alter biomes (& where crops can be Alter biomes (& where crops can be grown)grown)

Alter ocean currents / weatherAlter ocean currents / weather

Coastal flooding & degradationCoastal flooding & degradation

Intensified storms / Extreme weather Intensified storms / Extreme weather (droughts, floods, tropical storms, etc.)(droughts, floods, tropical storms, etc.)

Spread of water borne & tropical Spread of water borne & tropical diseasesdiseases

5 Scariest Things About 5 Scariest Things About Climate Change!!!Climate Change!!!

http://www.youtube.com/watch?v=M2Jxs7lR8ZI


What factors affect What factors affect Earth’s average Earth’s average temperaturetemperature ??

Factors Affecting Climate ChangeFactors Affecting Climate Change Positive Feedback MechanismsPositive Feedback Mechanisms

Factors that Factors that amplifyamplify climate changes climate changes

Negative Feedback MechanismsNegative Feedback Mechanisms• Factors that Factors that dampen / reducedampen / reduce climate changes climate changes

OceansOceans Store CO2 & heat in Store CO2 & heat in

deep (-)deep (-)• How much can it How much can it

handle? handle? UnknownUnknown• Increased temperatures Increased temperatures

cause increased release of cause increased release of dissolved CO2 (+)dissolved CO2 (+)

Increased evaporation Increased evaporation can add H2O vapor, can add H2O vapor, increasing warming (+)increasing warming (+)

Currents pull warm Currents pull warm water northwater north

Ice melt could disrupt Ice melt could disrupt currentscurrents• Disrupted currents could Disrupted currents could

lead to cooling of N. lead to cooling of N. HemisphereHemisphere

CloudsClouds Warmer temp’s create more cloudsWarmer temp’s create more clouds

• Could warm by trapping heat (+) or cool by Could warm by trapping heat (+) or cool by reflecting sunlight (-)reflecting sunlight (-)

Jet Contrails may have an impactJet Contrails may have an impact• Can form high thin clouds, trapping heat (+)Can form high thin clouds, trapping heat (+)

PollutionPollution

Aerosols (microscopic droplets or particles) Aerosols (microscopic droplets or particles) & soot can warm of cool air depending on & soot can warm of cool air depending on size and reflectivitysize and reflectivity

• Sulfate particles tend to cool (-)Sulfate particles tend to cool (-)

• Soot tends to warm (+)Soot tends to warm (+)

Not likely to have a major impact, b/c don’t Not likely to have a major impact, b/c don’t remain in atmosphere long & emissions remain in atmosphere long & emissions being reducedbeing reduced

Photosynthesis & MethanePhotosynthesis & Methane Higher CO2 levels would increase Higher CO2 levels would increase

photosynthesis which would photosynthesis which would remove CO2. (-)remove CO2. (-)

• Temporary - COTemporary - CO22 released when released when plants decay or burn & mature plants plants decay or burn & mature plants remove less CO2remove less CO2

CH4 (methane) released from CH4 (methane) released from bogs, wetlands, deep ocean floor bogs, wetlands, deep ocean floor & tundra soil (permafrost) faster in & tundra soil (permafrost) faster in warmer temps (+)warmer temps (+)

https://www.youtube.com/watch?v=NVpQnpWS2wU


What are some What are some possible beneficial possible beneficial

and harmful effects of and harmful effects of a warmer earth?a warmer earth?

Winners & LosersWinners & Losers Some areas will benefit from climate Some areas will benefit from climate

change, while others will lose.change, while others will lose.

Depends mostly on where you liveDepends mostly on where you live

Poor nations in the tropics will suffer mostPoor nations in the tropics will suffer most

EFFECTS OF GLOBAL WARMINGEFFECTS OF GLOBAL WARMING

Between 1979 and 2005, average Arctic Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue sea ice dropped 20% (as shown in blue hues above).hues above).


Sea Ice Melt: Pros & ConsSea Ice Melt: Pros & Cons

CONSCONSAs planet warms, As planet warms, convection transfers convection transfers surplus heat to poles, surplus heat to poles, increasing meltingincreasing melting

More water exposed More water exposed b/c of melt causes b/c of melt causes increase heat increase heat absorptionabsorption

PROSPROSOpens new areas to Opens new areas to shipping and oil/gas shipping and oil/gas explorationexploration

Increase some Increase some commercial fisheriescommercial fisheries

Land Ice / Mountaintop Land Ice / Mountaintop Glacier Melt: Pros & ConsGlacier Melt: Pros & Cons

CONSCONS Increases sea levelsIncreases sea levels

Rivers & streams fed Rivers & streams fed by glacial melt running by glacial melt running drydry

Fresh water shortagesFresh water shortages

Releases stored CO2 & Releases stored CO2 & CH4CH4

PROSPROS Increased agriculture Increased agriculture & timber harvest in & timber harvest in some areassome areas

Longer growing Longer growing seasonsseasons

Increased tourismIncreased tourism

Rising Sea LevelsRising Sea Levels

During this century During this century rising seas levels rising seas levels are projected to are projected to flood low-lying flood low-lying urban areas, urban areas, coastal estuaries, coastal estuaries, wetlands, coral wetlands, coral reefs, and barrier reefs, and barrier islands and islands and beaches.beaches.



A 2008 U.S. Geological Survey report estimates A 2008 U.S. Geological Survey report estimates a sea level rise of 3.0 - 6.5 ft (0.8-2 m) by 2100, a sea level rise of 3.0 - 6.5 ft (0.8-2 m) by 2100, with rise continuing for centuries with rise continuing for centuries



If seas levels If seas levels rise by 4-35 in rise by 4-35 in (9-88cm) (9-88cm) during this during this century, most century, most of the Maldives of the Maldives islands and islands and their coral their coral reefs will be reefs will be flooded.flooded.


Thermohaline Circulation:Thermohaline Circulation:Changing Ocean CurrentsChanging Ocean Currents

Global warming could alter ocean Global warming could alter ocean currents and cause both excessive currents and cause both excessive warming and severe cooling.warming and severe cooling.


Weather ExtremesWeather Extremes Shifting patterns of precipitation will increase / Shifting patterns of precipitation will increase /

intensify droughts in some areas, while other intensify droughts in some areas, while other areas will be affected by severe flooding from areas will be affected by severe flooding from prolonged / excess precipitation.prolonged / excess precipitation.

Researchers have not been able to show that Researchers have not been able to show that hurricane / typhoon activity will increase, but an hurricane / typhoon activity will increase, but an MIT study indicates that size and strength can MIT study indicates that size and strength can increase b/c of warmer surface watersincrease b/c of warmer surface waters

BiodiversityBiodiversity Could expand ranges & Could expand ranges &

populations of species that populations of species that could adapt to warmer could adapt to warmer climateclimate

At least 1 million species At least 1 million species could face premature could face premature extinction (especially extinction (especially specialized species or those specialized species or those w/ narrow ranges of w/ narrow ranges of tolerance)tolerance)

Most threatened ecosystems: Most threatened ecosystems: • coral reefs, polar seas, coastal coral reefs, polar seas, coastal

wetlands, alpine/arctic tundra, wetlands, alpine/arctic tundra, & mountain-tops& mountain-tops

Agriculture & Human HealthAgriculture & Human Health

In a warmer world, agricultural productivity may In a warmer world, agricultural productivity may increase in some areas and decrease in others.increase in some areas and decrease in others.

Crop and fish production in some areas could be Crop and fish production in some areas could be reduced by rising sea levels that would flood river reduced by rising sea levels that would flood river deltas.deltas.

Global warming will increase deaths from:Global warming will increase deaths from:Heat and disruption of food supply.Heat and disruption of food supply.Spread of tropical diseases to temperate regions.Spread of tropical diseases to temperate regions.Increase the number of environmental refugees.Increase the number of environmental refugees.

• Decreased deaths from cold weather• Increased deaths from heat and disease• Disruption of food and water supplies• Spread of tropical diseases to temperate

areas• Increased respiratory disease and pollen

allergies• Increased water pollution from coastal

flooding• Increased formation of photochemical

smog

Human Health

• Rising sea levels• Flooding of low-lying islands

and coastal cities• Flooding of coastal estuaries,

wetlands, and coral reefs• Beach erosion• Disruption of coastal fisheries• Contamination of coastal

aquifiers with salt water

Sea Level and Coastal Areas

• Changes in forest composition and locations

• Disappearance of some forests, especially ones at high elevations

• Increased fires from drying

• Loss of wildlife habitat and species

Forests•Changes in water supply

•Decreased water quality

• Increased drought

• Increased flooding

•Snowpack reduction

•Melting of mountaintop glaciers

Water Resources

• Shifts in food-growing areas

• Changes in crop yields• Increased irrigation

demands• Increased pests, crop

diseases, and weeds in warmer areas

Agriculture

• Extinction of some plant and animal species

• Loss of habitats

• Disruption of aquatic life

Biodiversity

• Prolonged heat waves and droughts

• Increased flooding from more frequent, intense, and heavy rainfall in some areas

Weather Extremes

• Increased deaths from heat and disruption of food supplies

• More environmental refugees

• Increased migration

Human Population

Benefits and Negative Impacts of Global WarmingBenefits and Negative Impacts of Global Warming


Why is global warming Why is global warming a difficult problem?a difficult problem?

Why is this such a difficult problem?Why is this such a difficult problem? Many complex causesMany complex causes

Global problemGlobal problem

Long term issueLong term issue

Harmful & beneficial impacts not spread equallyHarmful & beneficial impacts not spread equally

We can’t stop it, but we can slow it downWe can’t stop it, but we can slow it down

Some actions disrupt economies & lifestylesSome actions disrupt economies & lifestyles

Solutions:Solutions:• Will require International CooperationWill require International Cooperation• Must be long-term, not within the scope of our lifetimesMust be long-term, not within the scope of our lifetimes

StrategiesStrategies

MitigationMitigation• Reduce greenhouse Reduce greenhouse

gas emissions to gas emissions to slow rate of slow rate of temperature increasetemperature increase

AdaptationAdaptation• Recognize that some Recognize that some

warming is warming is unavoidable & devise unavoidable & devise strategies to reduce strategies to reduce its harmful effectsits harmful effects

When should we act?When should we act?

Wait & SeeWait & See – U.S. – U.S.

Act Now & Reduce RiskAct Now & Reduce Risk – – EuropeEurope• + 2500 scientists & 2700 + 2500 scientists & 2700

economistseconomists

Act Now as No Regrets Act Now as No Regrets StrategyStrategy• Even if problems don’t Even if problems don’t

arise, still improving health arise, still improving health of planetof planet


How can we slow How can we slow projected increases in projected increases in

the Earth’s temperature the Earth’s temperature and adapt to such and adapt to such

changes?changes?

Major Mitigation StrategiesMajor Mitigation Strategies Improve energy efficiency to reduce fossil fuel useImprove energy efficiency to reduce fossil fuel use

Shift from carbon based fossil fuels to carbon free Shift from carbon based fossil fuels to carbon free renewable energyrenewable energy

Stop deforestation & shift to more sustainable Stop deforestation & shift to more sustainable agriculture practicesagriculture practices

Store as much CO2 as possible in Store as much CO2 as possible in the soil, ocean, plants, undergroundthe soil, ocean, plants, underground

Reduce population Reduce population & poverty& poverty

Fig. 20-14, p. 481

Cut fossil fuel use (especially coal)

Shift from coal to natural gas

Improve energy efficiency***

Shift to renewable energy resources***

Transfer energy efficiency and renewable energy technologies to developing countries

Reduce deforestation

Use more sustainableagriculture and forestry

Limit urban sprawl

Reduce poverty

Slow population growth

Remove CO2 from smoke stack and vehicle emissions

Store (sequester)CO2 by planting trees***

Sequester CO2 deep underground***

Sequester CO2 in soil by using no-till cultivation and taking cropland out of production***

Sequester CO2 in the deep ocean***

Repair leaky natural gas pipelines and facilities

Use animal feeds that reduce CH4 emissions by belching cows

Solutions

Global Warming

Prevention Cleanup

Removing and Sequestering CORemoving and Sequestering CO22

Methods for Methods for removing COremoving CO22

from the from the atmosphere or atmosphere or from from smokestacks smokestacks and storing and storing (sequestering) (sequestering) it.it.



What is being done to What is being done to reduce greenhouse gas reduce greenhouse gas

emissions emissions internationally, internationally,

nationally, and locally?nationally, and locally?

What can Governments do?What can Governments do? Regulate CO2 & CH4 as air pollutionRegulate CO2 & CH4 as air pollution

Tax greenhouse gas emissions (Tax greenhouse gas emissions (carbon taxescarbon taxes) ) & usage (& usage (energy taxesenergy taxes))

Implement cap-and-trade for emissionsImplement cap-and-trade for emissions

Increase tax breaks for using green technologyIncrease tax breaks for using green technology

Transfer cleaner technologies to developing Transfer cleaner technologies to developing countriescountries

International Cooperation & International Cooperation & AgreementsAgreements

The Kyoto ProtocolThe Kyoto Protocol

• 187 of the world’s 194 countries ratifying the 187 of the world’s 194 countries ratifying the agreement by 2009 (not U.S.)agreement by 2009 (not U.S.)

• By 2012, 36 developed countries would cut their By 2012, 36 developed countries would cut their emissions of greenhouse gases to 5.2% below emissions of greenhouse gases to 5.2% below 1990 levels 1990 levels

• Developing countries excluded so as not to Developing countries excluded so as not to reduce economic growthreduce economic growth

The U.S. did not sign, but California and Maine are The U.S. did not sign, but California and Maine are participating.participating.

U.S. did not sign because developing countries such as U.S. did not sign because developing countries such as China, India and Brazil were excluded.China, India and Brazil were excluded.

Follow-up conferences in Copenhagen, Denmark, and Qatar ended in

non-binding agreements about

developing a second phase

Other Countries, States & Other Countries, States & Businesses Leading the WayBusinesses Leading the Way

Costa RicaCosta Rica• Aspires to be the first carbon-neutral country Aspires to be the first carbon-neutral country

by 2030by 2030

30+ U.S. states have set goals for 30+ U.S. states have set goals for reducing greenhouse gas emissionsreducing greenhouse gas emissions• California’s goal = 33% of electricity from California’s goal = 33% of electricity from

renewable sources by 2030renewable sources by 2030

Companies & Colleges/UniversitiesCompanies & Colleges/Universities• DuPont has cut emissions by 72% saving $3 DuPont has cut emissions by 72% saving $3

billionbillion

Fig. 20-16, p. 485

Reducing CO2 Emissions

• Drive a fuel-efficient car, walk, bike, carpool, and use mass transit

• Use energy-efficient windows, appliances, and lights

• Heavily insulate your house and seal all drafts

• Reduce garbage by recycling and reuse

• Use compact fluorescent bulbs

• Plant trees to shade your house during summer

• Insulate hot water heater & set it no higher than 49°C (120°F)

• Wash laundry in warm or cold water, and hang to dry

• Use low-flow shower head

• Buy products from companies that are trying to reduce their impact on climate

• Demand that the government make climate change an urgent priority

What Can You Do?

• Eat less or no meat

Fig. 20-17, p. 485

Move hazardous material storage tanks away

from coast

Connect wildlifereserves with corridors

Develop crops thatneed less water

Waste less water

Move people awayfrom low-lyingcoastal areas

Stockpile 1- to 5-yearsupply of key foods

Expand existingwildlife reserves

toward poles

Prohibit new constructionon low-lying coastal areasor build houses on stilts

AdaptationAdaptation SolutionsSolutions


How have human How have human activities depleted ozone activities depleted ozone in the stratosphere, and in the stratosphere, and

why should we carewhy should we care??

Ozone LayerOzone Layer Ozone blocks 95% of UV radiationOzone blocks 95% of UV radiation

• Chlorofluorocarbons (CFC’s) have lowered Chlorofluorocarbons (CFC’s) have lowered concentrations of ozone in stratosphereconcentrations of ozone in stratosphere

• Less ozone = MORE UV radiationLess ozone = MORE UV radiation

• Poses a serious threat to human, animals Poses a serious threat to human, animals and plants and plants

Rowland & MolinaRowland & Molina 1974 – University of California Irvine1974 – University of California Irvine

Discovered CFC’s cause decrease in Discovered CFC’s cause decrease in ozone concentrations in stratosphereozone concentrations in stratosphere

In 1988 the manufacturing of CFCs was In 1988 the manufacturing of CFCs was stopped in the U.S. stopped in the U.S.

In 1995 Rowland and Molina In 1995 Rowland and Molina were awarded the Nobel Prize were awarded the Nobel Prize in chemistryin chemistry

Causes of Ozone DepletionCauses of Ozone Depletion

Breakdown of CFC’s Breakdown of CFC’s

• Chlorofluorocarbons (Freons)Chlorofluorocarbons (Freons)

• React w/ UV radiation producing Cl and F and Br React w/ UV radiation producing Cl and F and Br atoms that break down ozone (O3)atoms that break down ozone (O3)

• CFC’s are in styrofoam, air conditioning & CFC’s are in styrofoam, air conditioning &

refrigerating fluid, some aerosolsrefrigerating fluid, some aerosols

SunOnce free, the

chlorine atom is off to attack another ozone

moleculeand begin the cycle

again.

A free oxygen atom pulls the oxygen atom off

the chlorine monoxide molecule to form O2.

The chlorine atom and the oxygen atom join to

form a chlorine monoxide molecule (ClO).

UV radiation

Cl Cl

ClC

F

The chlorine atom attacks an ozone (O3) molecule, pulling an oxygen atom

off it and leaving an oxygen

molecule (O2).

Cl

Cl

OO

O

Cl

ClO

ClO

OO

OO

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule,

such as CFCl3, breaking off a chlorine atom and leaving CFCl2.

O

Fig. 20-18, p. 486

Ozone “Hole”Ozone “Hole” Ozone thinning Ozone thinning

considerably over considerably over Arctic & AntarcticaArctic & Antarctica

During 4 months of During 4 months of the year, up to half the year, up to half the ozone over the the ozone over the Antarctic is depleted Antarctic is depleted (11-38% over Arctic)(11-38% over Arctic)

Thinning occurring Thinning occurring everywhere except everywhere except tropicstropics

Effects of Ozone Depletion

Natural Capital Degradation

Human Health• Worse sunburn• More eye cataracts• More skin cancers• Immune system suppression

Food and Forests• Reduced yields for some crops• Reduced seafood supplies from reduced phytoplankton• Decreased forest productivity for UV-sensitive tree species

Wildlife• Increased eye cataracts in some species• Decreased population of aquatic species sensitive to UV radiation• Reduced population of surface phytoplankton• Disrupted aquatic food webs from reduced phytoplankton

Air Pollution and Materials• Increased acid deposition• Increased photochemical smog• Degradation of outdoor paints and plastics

Global Warming• Accelerated warming because of decreased ocean uptake of CO2 from

atmosphere by phytoplankton and CFCs acting as greenhouse gases

Fig. 16-17, p. 384

Consequences of Ozone LossConsequences of Ozone Loss

Why should we care?Why should we care?

Exposure to UV radiation Exposure to UV radiation is a major cause of skin is a major cause of skin cancers.cancers.

Fig. 20-22, p. 489

This long-wavelength(low-energy) form of UV

radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin

cancer.

This shorter-wavelength (high-energy) formof UV radiation causes sunburn, premature

aging, and wrinkling. It is largely responsiblefor basal and squamous cell carcinomasand plays a role in malignant melanoma.

Epidermis

Squamous Cell Carcinoma

Basal Cell Carcinoma

Melanoma

Sweatgland

Dermis

Squamous cells

Thin layer ofdead cells

Basal layer

Melanocyte cells

Bloodvessels

UltravioletB

UltravioletA

Hair

Basalcell


How can we slow and How can we slow and eventually reverse ozone eventually reverse ozone

depletion in the stratosphere depletion in the stratosphere caused by human actions?caused by human actions?

Protecting the Ozone LayerProtecting the Ozone Layer

International agreements to International agreements to eliminate the production of eliminate the production of CFCs & ODC’sCFCs & ODC’s• Montreal Protocol (1987) Montreal Protocol (1987)

Cut emissions of CFC use by 35%Cut emissions of CFC use by 35%

• Copenhagen Protocol(1992)Copenhagen Protocol(1992) Accelerated phase out of CFC’s & ODC’sAccelerated phase out of CFC’s & ODC’s

Create alternatives like alcohol Create alternatives like alcohol based coolants, citrus based based coolants, citrus based solvents, pump sprayerssolvents, pump sprayers

Fig. 20-23, p. 490

What Can You Do?

• Stay out of the sun, especially between 10 A.M. and 3 P.M.

• Do not use tanning parlors or sunlamps.

• When in the sun, wear protective clothing and sun– glasses that protect against UV-A and UV-B radiation.

• Be aware that overcast skies do not protect you.

• Do not expose yourself to the sun if you are takingantibiotics or birth control pills.

• Use a sunscreen with a protection factor of 15 or 30

anytime you are in the sun if you have light skin. • Examine your skin and scalp at least once a month for

moles or warts that change in size, shape, or color or sores that keep oozing, bleeding, and crusting over. If

you observe any of these signs, consult a doctor immediately.

Reducing Exposure to UV Radiation

Documents

Chapter 20 Climate Change & Ozone Loss. Essential Question #1 How have the Earth’s temperature and climate changed in the past & how are greenhouse gases