Climate Change & Ozone Loss Chapter 21. Temperature Changes 900,000 years – alternating cycles of freezing & thawing Glacial period- ice age Interglacial.

Climate Change & Ozone Loss

Chapter 21

Temperature Changes

900,000 years – alternating cycles of freezing & thawing

Glacial period- ice age Interglacial period- between ice ages

Average temperature over past 900,000 years

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

Figure 21-2a Page 463

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

Figure 21-2cPage 463

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

Figure 21-2dPage 463

Studying Climate Change

Ice cores- drilled from ice – info about tropospheric composition, temperature trends, greenhouse gas concentrations, solar activity, snowfall, forest fire frequency

Core samples- into bottoms of lakes, ponds, & swamps – analyze sediment for pollen, fossils, & other clues about plants

Infrared sensors – temperatures

Direct measurements about tropospheric temperature, composition, trends

Air samples – changes in chemical composition

Natural Greenhouse Effect

Warming of Earth’s lower troposphere & surface

Widely accepted theory due to numerous lab experiments & measurements of atmospheric temperatures at different altitudes (since 1896)

Natural Cooling Process

Large quantities of heat are absorbed by evaporation of liquid surface water

Water vapor rises Condenses (clouds) & releases heat higher in

the atmosphere

Major Greenhouse Gases

Water vapor CO2

Human Activities & Greenhouse Gases Rise in use of fossil fuels Deforestation & clearing/burning of

grasslands to raise crops & build cities Raising of increasing number of cattle & other

livestock Cultivation of rice paddies & inorganic

fertilizers

U.S.- 4.6% of population; 24% of emissions

Signs of Troposphere Warming

20th century- hottest in last 1000 years Average surface temperature up 0.6°C

(1.1°F) – mostly since 1980 16 warmest years since 1980 Melting/shrinking of glaciers & floating sea ice Rising sea level

Changes at the Poles

Greater temperature changes Melting & thinning sea ice faster than it is

formed Higher albedo – less reflectivity

Figure 21-9Page 470

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 biotoa

Shallow ocean

Long-termstorage

Deep ocean

2001 IPCC Results

Latest climate models match records of global temperature changes very closely

Most global warming over the last 50 years is due to human activities

90% probability that surface temperature will increase up to 10°F by 2100

Figure 21-11Page 471

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)

Climate Shift

Availability of water resources (evaporation/precipitation rates)

Change wind patterns & weather Alter climates (dry/moist areas) Alter ocean currents Shift area of productive farm land Increase average sea level & flood coastal

areas, cities, & low-lying islands Change structure & location of biomes* Little time to deal with climate changes

Antarctica

GreenlandGreenland

Figure 21-12Page 472

Cloud Cover & Climate Change

Warming effect- warmer temperatures increase evaporation of surface water & create more clouds

Cooling effect- absorbing & releasing heat or by reflecting more sunlight back into space

Air Pollution & Climate Change

May increase cloud cover Clouds reflect more sunlight back into space

(may counteract the increase of greenhouse gases)

Photosynthesis & Climate Change

Increased C02 increases the rate of photosynthesis

This would remove excess CO2 from atmosphere & slow global warming

Methane & Global Warming

Increased methane would accelerate global warming

Sources of methane: Bogs & wetlands – methane hydrates Melting of permafrost in tundra & boreal

forests

• 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

Figure 21-13Page 475

Atmospheric Warming / Developing Countries Harmful effects of moderate global warming

will fall on people & economies in poorer tropical & subtropical nations

Figure 21-14Page 475

• Less severe winters

• More precipitation in some dry areas

• Less precipitation in some wet areas • Increased food production in some areas

• Expanded population and range for some plant and animal species adapted to higher temperatures

What To Do…

Do more research before acting (wait-and-see strategy)

Act now to reduce risks from climate change brought about by global warming (precautionary principle)

Act now as part of a no-regrets strategy

Figure 21-17Page 479

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

Removing CO2 from Atmosphere

Immature trees- only temporary because trees release stored CO2 back into atmosphere when they die, decompose, or are burned

Plants that store in soil (like switchgrass)- warmer temperatures can increase decomposition in soils & return some to atmosphere

Deep underground reservoirs- pump into unminable coal seams & abandoned oil fields

Figure 21-18Page 480

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

Governments Reducing the Threat

Phase in output-based carbon taxes on each unit of CO2 emitted by fossil fuels (especially coal & gasoline) or input-based energy taxes on each unit that is burned

Level economic playing field- greatly increasing government subsidies for energy-efficiency & carbon-free renewable energy technologies, carbon sequestration, more sustainable agriculture, & by phasing out subsidies & tax breaks for using fossil fuels

Technology transfer- governments of developed countries could fund transfer of energy-efficiency & carbon-free renewable energy technologies, carbon sequestration, more sustainable agriculture technologies to developing countries

Buying/Selling Emission Permits

Stimulates companies to develop new technologies to reduce greenhouse gas emissions & increase profits

Credits are earned by: Improving energy efficiency Switching from coal to natural gas or

renewable energies Adopting farming, ranching, soil building, &

conservation practices Sequestering CO2

Disadvantages: Difficult to monitor compliance due to burning

of carbon fuels in homes, vehicles, factories, & crop fields

Politically difficult for nations to agree on credits & how to divide them

Kyoto Protocol

39 developed countries to cut emissions of CO2, CH4, N20 by 2012

Did not require poorer developing countries to make cuts until later

Allows emission trading By 2004- ratified by 120 countries U.S.- withdrew (GWB) in 2001- too expensive

& did not require emissions reductions by developing countries such as China & India (large & increasing greenhouse emissions)

New Treaty

Include developing countries, set achievable goals, effective trading program for emissions, evaluate strategies for adapting to ecological & economic effects of global warming

Reducing Emissions

Large Scale Use natural gas instead of coal Improve energy efficiency in industry & homes Raising taxes on gasoline Government increased R&D & tax breaks for

renewable energy Phasing out coal subsidies Shutting down inefficient carbon-free electric

plants

Small scale (individuals/schools) Buy carbon-free electricity Buy renewable energy

Figure 21-20Page 483

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

Figure 21-20Page 483

Difficulties in Dealing with Global Warming & Climate Change Poorly understood cause/effect Long-term problems Harmful/beneficial effects are uneven Reduction of emissions would take

unprecedented international response

Stratospheric Ozone Depletion

Thinning of ozone layer Serious threat to humans, other animals, &

primary producers

Chemical Causes

CFCs Freons

Used for: Coolants Propellants Cleaners Fumigants Packaging bubbles HBCFs- fire

extinguishers HCl- from space

shuttles

How they work…

Insoluble in water & chemically unreactive so they remain in troposphere

Lifted into stratosphere by convection, random drift, & turbulence in troposphere

Break down in stratosphere under UV radiation

Releases ions that accelerate the break down of ozone

Seasonal Depletion of Ozone

Upper stratosphere over Antarctica disappeared during late winter & spring

Figure 21-24Page 486

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

Cancers

Squamous cell skin cancer- cells in upper layer of epidermis; caused by exposure to sunlight or tanning lamps (UVB)

Basal cell skin cancer- lower epidermis cells (UVB)

Malignant melanoma- occurs in pigmented areas such as moles; grows quickly & can spread to other body parts

Figure 21-26Page 488

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.

Restoring the Ozone

To 1980 levels – 50 years To 1950 levels – 100 years

Policies for Emission Reduction

Montreal Protocol – 1987; 37 nations signed treaty to cut CFC emissions by 35% by 2000

Copenhagen Protocol – 1990; 96 countries; amendment which accelerated the phasing out of key ozone-depleting chemicals

Results

Ozone depletion in stratosphere has been cooling troposphere & has helped offset (or disguise) 30% of warming from greenhouse gas emissions

Precedent for global cooperation & action to avert potential disaster

International Treaty

Convincing & dramatic scientific evidence of serious problem

CFCs produced by small number of international companies

Certainty that CFC sales would decline unleashed economic & creative resources of private sector to find profitable substitute chemicals