Climate Change and Ozone LossClimate Change and Ozone Loss

Key ConceptsKey Concepts

Changes in Earth’s climate over time Changes in Earth’s climate over time

Factors affecting climate Factors affecting climate

Possible effects of global warming Possible effects of global warming

Adapting to climate change Adapting to climate change

Human impacts on the ozone layer Human impacts on the ozone layer

Protecting and restoring the ozone layer Protecting and restoring the ozone layer

Past Climate ChangesPast Climate Changes

Past globaltemperatures

Past globaltemperatures

Recent trends in global temperatures

Recent trends in global temperatures

Temperature change over past 22,000 years

Years ago

Tem

per

atu

re c

han

ge

(°C

)

20,000 10,000 2,000 1,000 200 100 Now

-5

-4

-3

-2

-1

0

1

2

End oflast iceage

Agriculture established

Average temperature over past10,000 years = 15°C (59°F)

Temperature change over past 1,000 years

Year

Tem

per

atu

re c

han

ge

(°C

)

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2101

-1.0

-0.5

0.0

0.5

1.0

Average temperature over past 130 years

Year

Ave

rag

e su

rfac

e te

mp

erat

ure

(°C

)

1860 1880 1900 1920 1940 1960 1980 2000 2020

13.6

13.8

14.0

14.2

14.4

14.6

14.8

15.0

The Greenhouse EffectThe Greenhouse Effect

Greenhouse effect Greenhouse effect Greenhouse gases Greenhouse gases

Table 21-1 Major Greenhouse Gases from Human Activities

Greenhouse Gas

Carbon dioxide (CO2)

Methane (CH4)

Nitrous oxide (N2O)

Chlorofluorocarbons(CFCs)*

Hydrochloro-fluorocarbons (HCFCs)

Hydrofluorocarbons(HFCs)

Halons

Carbon tetrachloride

Average Time in the Troposphere

100–120 years

12–18 years

114–120 years

11–20 years (65–110 years in stratosphere)

9–390

15–390

65

42

Human Sources

Fossil fuel burning, especially coal (70–75%), deforestation, and plant burning

Rice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelines

Fossil fuel burning, fertilizers, livestock wastes, and nylon production

Air conditioners, refrigerators, plastic foams

Air conditioners, refrigerators, plastic foams

Air conditioners, refrigerators, plastic foams

Fire extinguishers

Cleaning solvent

Relative Warming Potential (compared to CO2)

1

23

296

900–8,300

470–2,000

130–12,700

5,500

1,400

Carbon dioxide

Temperaturechange End of

last ice age

160 120 80 40 0Thousands of years before present

Co

nc

entr

ati

on

of

carb

on

dio

xid

ein

th

e a

tmo

sph

ere

(p

pm

)

180

200

220

240

260

280

300

320

340

360

380

–10.0

–7.5

–5.0

–2.5

0

+2.5

Va

riat

ion

of

tem

pe

ratu

re (

˚C)

fro

m c

urr

en

t le

vel

Carbon dioxide (CO2)

Year1800 1900 2000 2100

260

310

360

410P

arts

per

mil

lio

n

Methane (CH4)

Year

1800 1900 2000 21000.6

1.2

1.8

2.4P

arts

per

mil

lio

n

Year

Par

ts p

er m

illi

on

1800 1900 2000 2100260

290

300

310

320

Nitrous oxide (N2O)

Climate Change and Human ActivitiesClimate Change and Human Activities

Increased use of fossil fuelsIncreased use of fossil fuels

Deforestation Deforestation

Global warmingGlobal warming

Melting icecaps and glaciersMelting icecaps and glaciers

Rising sea levelRising sea level

Table 21-2 Major Characteristics of Global Warming and Ozone Depletion

Characteristic

Region ofatmosphere involved

Majorsubstances involved

Interaction with radiation

Nature of problem

Possible consequences

Possible responses

Ozone Depletion

Stratosphere.

O3, O2, chlorofluorocarbons (CFCs).

About 95% of incoming ultraviolet (UV)radiation from the sun is absorbed by O3molecules in the stratosphere and does not reach the earth’s surface.

CFCs and other ozone-depleting chemicals released into the troposphere by human activities have made their way to the stratosphere, where they decrease O3 concentration. This can allow more harmful UV radiation to reach the earth’s surface.

Increased incidence of skin cancer, eyecataracts, and immune system suppression and damage to crops and phytoplankton.

Eliminate or find acceptable substitutes for CFCs and other ozone-depleting chemicals.

Global Warming

Troposphere.

CO2, CH4, N2O (greenhouse gases).

Molecules of greenhouse gases absorb infrared (IR) radiation from the earth’s surface, vibrate, and release longer-wavelength IR radiation (heat) into the lower troposphere. This natural greenhouse effect helps warm the lower troposphere.

There is a high (90–99%) probability that increasing concentrations of greenhouse gases in the troposphere from burning fossil fuels,deforestation, and agriculture are enhancing the natural greenhouse effect and raising the earth’s average surface temperature (Figure 21-2, bottom right, and Figure 21-11, p. 471).

Changes in climate, agricultural productivity,water supplies, and sea level.

Decrease fossil fuel use and deforestation;prepare for climate change.

Greenland

Oceans 5%

Bare sand 30–60%

Grass 15–25%

Clouds 50–55%

Snow 80–90%

City 10–15%

Forest 5%

Today’s sea level

Years before present Present

250,000 200,000 150,000 100,000 50,000 0

–130

0

–426

0

Hei

gh

t ab

ove

or

bel

ow

pre

sen

t se

a le

vel

(met

ers)

Hei

gh

t ab

ove

or

bel

ow

p

rese

nt

sea

leve

l (f

eet)

Projecting Future Changes in Earth’s ClimateProjecting Future Changes in Earth’s Climate

Climate modelsClimate models

Apparent influence of human activitiesApparent influence of human activities

Could be natural changesCould be natural changes

Troposphere

Aerosols

Greenhousegases

Warmingfromdecrease

Cooling from increase

CO2 removal by plants and soil organisms

CO2 emissions from land cleaning, fires, and decay

Heat andCO2 removal

Heat andCO2 emissions

Ice and snow cover

Natural and human emissions

Land and soil biota

Shallow ocean

Long-termstorage

Deep ocean

Cell

Clouds

OceanLand

Year

0

1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Ch

ang

e i

n t

em

pe

ratu

re (

ºC)

Factors Affecting the Earth’s TemperatureFactors Affecting the Earth’s Temperature

Changes in solar outputChanges in solar output

Changes in Earth’s albedoChanges in Earth’s albedo

Moderating effect of oceansModerating effect of oceans

Clouds and water vaporClouds and water vapor

Air pollutionAir pollution

Antarctica

GreenlandGreenland

Some Possible Effects of a Warmer WorldSome Possible Effects of a Warmer World

Possible Benefits from a Warmer AtmospherePossible Benefits from a Warmer Atmosphere

Less severe wintersMore precipitation in some dry areasLess precipitation in some wet areasIncreased food production in some areasExpanded population and ranges of some

species

Less severe wintersMore precipitation in some dry areasLess precipitation in some wet areasIncreased food production in some areasExpanded population and ranges of some

species

Presentrange

Futurerange

Overlap

Year

02010 2020 2030 2040 2050 2060 2070 2080 2090 2100

10

20

30

40

50

60

70

80

90

100

Mea

n S

ea-

Le

vel

Ris

es (

cen

tim

eter

s)

High ProjectionShanghai, New Orleans,and other low-lying citieslargely underwater

Medium ProjectionMore than a third of U.S.

wetlands underwater

Low Projection

Treeplantation

Coalpower plant

Tanker deliversCO2 from plantto rig

Oil rig

Crop fieldSwitchgrass

Spent oil reservoir isused for CO2 deposit

CO2 is pumpeddown to reservoir through abandoned oil field

Abandonedoil field

CO2 ispumped downfrom rig for deepocean disposal

= CO2 deposit

= CO2 pumping

Reducing CO2 Emissions

What Can You Do?

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

• Use energy-efficient windows

• Use energy-efficient appliances and lights

• Heavily insulate your house and seal all drafts

• Reduce garbage by recycling and reuse

• Insulate hot water heater

• Use compact fluorescent bulbs

• Plant trees to shade your house during summer

• Set water heater no higher than 49°C (120°F)

• Wash laundry in warm or cold water

• Use low-flow shower head

Solutions: Dealing with the Threat of Climate ChangeSolutions: Dealing with the Threat of Climate Change

OptionsOptions

Do nothing Do nothing

Do more research Do more research

Act now to reduce risks

Act now to reduce risks

Precautionary principle

Precautionary principle

Global Warming

Solutions

Prevention Cleanup

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 sustainable agriculture

Limit urban sprawl

Reduce poverty

Slow population growth

Store (sequester) CO2 by planting trees

Sequester CO2 deep underground

Sequester CO2 in soil by using no-till cultivation and taking crop land out of production

Sequester CO2 in the deep ocean

Repair leaky natural gas pipelines and facilities

Use feeds that reduce CH4 emissions by belching cows

Remove CO2 from smokestackand vehicle emissions

Reducing Greenhouse Gas EmissionsReducing Greenhouse Gas Emissions

Kyoto Treaty (1997) Kyoto Treaty (1997)

Other reductions in CO2 Other reductions in CO2

U.S. withdraws from Kyoto Treaty (2001) U.S. withdraws from Kyoto Treaty (2001)

Loss of the Ozone Layer: Reasons for ConcernLoss of the Ozone Layer: Reasons for Concern

Increased incidence and severity of sunburn Increased incidence and severity of sunburn

Increase in eye cataracts Increase in eye cataracts

Increased incidence of skin cancer Increased incidence of skin cancer

Immune system suppression Immune system suppression

Increase in acid deposition Increase in acid deposition

Lower crop yields and decline in productivity Lower crop yields and decline in productivity

When did it all begin?When did it all begin?

• Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group.

• They were monitoring the atmosphere above Antarctica from a research station

Research Station in AntarcticaResearch Station in Antarctica

The AtmosphereThe Atmosphere

•

Where and how ozone is formed?Where and how ozone is formed?

• Ozone (O3) forms a layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles.

• It is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating (or "splitting") oxygen molecules (O2) to atomic

oxygen (O).

• The atomic oxygen quickly combines with further oxygen molecules to form ozone (O3 )

Where is the Ozone “hole” ?Where is the Ozone “hole” ?

• Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted at certain times of the year.

• This is mainly due to the release of man-made chemicals containing chlorine such as CFC's (Chlorofluorocarbons), but also compounds containing bromine, other related halogen compounds and also nitrogen oxides (NOx).

Ozone Depleting ChemicalsOzone Depleting Chemicals

Chlorofluorocarbons (CFCs) Chlorofluorocarbons (CFCs)

Halons Halons

Methyl bromide Methyl bromide

Carbon tetrachloride Carbon tetrachloride

Methyl chloroform Methyl chloroform

Hydrogen chloride Hydrogen chloride

Former Uses of CFCsFormer Uses of CFCs

Air Conditioners

Refrigerators

Spray cans

Cleaners for electronic parts

Sterilizing medical instruments

Fumigants for granaries and cargo ships

Air Conditioners

Refrigerators

Spray cans

Cleaners for electronic parts

Sterilizing medical instruments

Fumigants for granaries and cargo ships

CFC’s in the airCFC’s in the air

Ozone Depletion in the StratosphereOzone Depletion in the Stratosphere

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leaving CFCl2.

UV radiation

Sun

Once 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).

The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2).

Cl

Cl

ClC

F

Cl

Cl

OO

Cl

OO

O

Cl

O

OO

ClO

O

Summary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2

Cl + O Cl + O2

Repeated many times

Seasonal Ozone Layer Thinning at the PolesSeasonal Ozone Layer Thinning at the Poles

Ozone thinning (hole)Ozone thinning (hole)

Polar vortexPolar vortex

January 1995 October 1995January 1995 October 1995

It’s getting bigger……..It’s getting bigger……..

• Satellite measurements in September 2000 revealed that the stratospheric ozone “hole” over the Antarctic had a reached a record 28.3 million square kilometers (some one million sq. km more than the previous record, in 1998).

October 1980- October 2002 October 1980- October 2002

Year

1970 1975 1990 2000 200519851955 1960 1965 1980 1995

400

350

300

250

200

150

100

To

tal o

zon

e (D

ob

son

un

its)

October monthly means

August 6, 2003

October 11, 2003

35

30

25

20

15

10

5

0 5 10 15Ozone partial pressure (milipascals)

Alt

itu

de

(kil

om

eter

s)

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

What are some of the dangers associated with the ozone hole?What are some of the dangers associated with the ozone hole?

• Experts predict that an estimated 10 % reduction in the ozone layer will result in a 25% increase in non-melanoma skin cancer rates for temperate latitudes by the year 2050.

Skin CancersSkin Cancers

Squamous Cell Carcinoma

Melanoma

Basal Cell Carcinoma

Ultraviolet A Ultraviolet B

Thin layer ofdead cells

Squamouscells

Basallayer

Melanocytecells

Basalcell

Bloodvessels

HairEpidermis

Sweatgland

Dermis

Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma

Reducing Exposure to UV-Radiation

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 taking antibiotics or birth control pills.

• Use a sunscreen with a protection factor of 15 or 25 ifyou 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.

Skin Cancer Fact SheetSkin Cancer Fact Sheet

• Over half of all new cancers are skin cancers. 

• More than 1 million new cases of skin cancer will be diagnosed in the United States this year. 

   An estimated 10,250 people will die of skin cancer this year.

  One person dies of melanoma every hour. 

More FactsMore Facts

• At current rates one in 37 Americans have a lifetime risk of developing melanoma and one in 65 Americans have a lifetime risk of developing invasive melanoma.

• The incidence of melanoma more than tripled among Caucasians between 1980 and 2003. 

• More than 77 percent of skin cancer deaths are from melanoma.

Solutions: Protecting the Ozone LayerSolutions: Protecting the Ozone Layer

CFC substitutes CFC substitutes

Montreal Protocol Montreal Protocol

Copenhagen Protocol Copenhagen Protocol

Year

1950 1975 2000 2025 2050 2075 2100

3,000

0

6,000

9,000

12,000

15,000

Ab

un

da

nc

e (p

art

s p

er

trill

ion

)

No protocol

1987MontrealProtocol

1992CopenhagenProtocol