Chapter 7

ATMOSPHERE AND CLIMATE

The Atmosphere

• Is a thin layer of gases that surrounds the earth• Extends thousands of km above the surface• The reason there is life on Earth – we are

protected from most of the sun’s radiation• Allows some light to reach the surface, supplying

energy and allowing photosynthesis (O2 and CO2)• 78% nitrogen, 21% oxygen, 1%= water vapor,

argon, carbon dioxide, neon, helium, and other gases

HOW PHOTOSYNTHESIS CHANGED THE ATMOSPHERE

• The early atmosphere contained little oxygen.

• Bacteria appeared about 4 bya and evolved the ability to perform photosynthesis 6CO2 + 6H2O + sun energy → C6H12O6 + 6O2

• When organisms break down food molecules during cellular respiration, CO2 is released into the air. C6H12O6 + O2 → CO2 + H2O + Energy

The 4 Layers

TroposphereTroposphere

– 75–80% of the earth’s air mass– Closest to the earth's surface– 0-11 km above sea level – Chemical composition of air• Nitrogen 78%• Oxygen 21%• H20, CO2, trace amounts of others (Ar)

– Weather, climate and all life forms exist here– As altitude increases, temperature decreases

StratosphereStratosphere

• 11-50 km (6-30 miles) above Earth's surface– Similar composition to the troposphere, with 2

exceptions• Much less water (1/1000)• O3, ozone layer

• As altitude increases, temperature increases• Air motion is horizontal• Airplanes fly here

MesosphereMesosphere 50-80 km (30-50 miles)50-80 km (30-50 miles) Middle atmosphere – Air thin, pressure low,Middle atmosphere – Air thin, pressure low, Need oxygen to live in this region. Air quite cold Need oxygen to live in this region. Air quite cold

-90°C (-130°F) near the top of mesosphere-90°C (-130°F) near the top of mesosphere

ThermosphereThermosphere 80-500 km (50-310 miles) Very few atoms and molecules in this region. Intense UV – breaks O2 and N2 bonds International Space Station is here

Greenhouse Effect Greenhouse Effect • Greenhouse effect – the trapping of infrared

radiation from the sun by gases in earth’s atmosphere which warms the planet

• Raises earth’s temp to an average of 59 ⁰F. Without the greenhouse effect, the average temp would be 0⁰F.

Global Warming

• Global warming – increase in Earth’s average surface temp. caused by an increase in greenhouse gases

• “runaway greenhouse effect”• Earth’s average temperature has risen 1 ° F in last Earth’s average temperature has risen 1 ° F in last

100 years.100 years.• Some argue natural fluctuation; however,

corresponds w/ rising greenhouse gases• Evidence: 14 record hottest years post-1980,

glaciers retreating• Some estimate by 2050 2 –4 ° C change.

GREENHOUSE GASES

• CARBON DIOXIDE• METHANE• NITROUS OXIDE• CFCs • WATER VAPOR

Greenhouse GasesCO2 – most abundant greenhouse gas (GHG)

Sources: burning fossil fuels, deforestationIce cores have shown that CO2 increasing in

atmosphere – 35% higher than pre-Industrial Rev.• Natural cycling of CONatural cycling of CO22 levels levels

• Seasonal shift in COSeasonal shift in CO22 production; high fall; low production; high fall; low springspring

• Ocean acts as “sink,” absorbing large amounts.• Vegetation acts as a sink (until it dies or is cut down)• 1 kg burned fossil fuels = 3 kg CO1 kg burned fossil fuels = 3 kg CO22

Vostok Ice Core• Deepest drilling of ice took

place. • The ice removed was nearly

a half a million years old. • Graph = CO2 levels going

back to over 400,000 years before present.

• The (kyr BP) means kilo=1,000 years Before Present.

• CO2 rises and falls about every 100,000 years.

• At present we are at a high point again.

CO2 - Did you know…

• Burning 1 gallon of gasoline produces 9 kg of carbon dioxide?

• Using one kWh of electricity from a coal-fired generating plant produces 1 kg of carbon dioxide?

• Burning 100 cubic feet of natural gas produces 5.5 kg of carbon dioxide?

• 1 kg= 2.2 pounds So 1 gallon produces almost 20 pounds of CO2

The Jones Family

• Complete the worksheet to see how the Jones family contributes to greenhouse gas emissions.

Charles Keeling – 1958Mauna Loa, Hawaii

• Measured the amount of CO2 in the air

• 314 parts per million (ppm) in March, 1958• In late summer, the levels had fallen. CO2

levels rose in the winter. Why?– Growing plants use more CO2 for photosynthesis

than they do in the winter!

• Levels have increased from 280 ppm in 1750 to 367 ppm today

CO2 Emissions

• Countries:– Largest emitters: China (6534 million metric tons):

US (5833): Russia (1729): India (1495): Japan (1214)

• Per Capita:– Australia - 20.8 tons (437, country)– US- 19.8 tons– China – 4.91– India: 1.31

Other Greenhouse GasesMethane (CH4) – 21 times more warming effect than

CO2 and increasing at 8 times the rate.

• Methane production is faster than broken down• Main sources are wetlands, rice fields, fossil fuels,

livestock• Remains in the air about 12 years

Greenhouse Gases• Nitrous oxides – slow to breakdown (120 yrs)– Sources are fossil fuels, fertilizers, deforestation

• CFCs– slow breakdown; absorb 10,000 X more infrared than CO2 (100 + years)– Sources are foams, aerosols, refrigerants, solvents

• Water vapor – Warmed by CO2, the atmosphere is thus able to

absorb more water vapor. And that water vapor, in turn, causes further warming—it amplifies the

effects of carbon dioxide.

• Global average temperatures - surface temperatures collected from land and ocean-based stations .

• Compiled by the Climatic Research Unit of the University of East Anglia and the Hadley Centre of the UK Meteorological Office.

Predicted Results Of Global Warming

• Weather patterns will change - more hurricanes, typhoons, flooding and droughts

• Agriculture – weather patterns will move farther north, shifting farmland

• Sea Levels - polar regions warm, icebergs melt, sea levels rise. Warming water also expands. Coastal areas may flood

• http://news.discovery.com/videos/global-warming-videos/ (Walrus, tiger, Alaska)

Melting of Alaska’s Muir Glacier between 1948 and 2004

Predicted Results Of Global Warming

• Human health will be affected– Heat index, more ground level ozone, more

infectious diseases. – Diseases that normally occur near equator will

move northward. Diseases spread by mosquitoes and other insects due to warmer/wetter climates.

– Malaria, dengue fever, yellow fever and encephalitis

Predicted Results Of Global Warming

Albedo & Global Warming(albedo= ability of a surface to reflect

light)• Rising global temperatures cause greater evaporation

of water vapor into the atmosphere • Water vapor is a powerful greenhouse gas, so an

increase in water vapor might produce more warming.

OR• More water vapor might cause more clouds to form,

increasing Earth's overall albedo, & reflecting incoming sunlight back into space.

• This would provide a net cooling effect.• Might possibly induce a period of "global cooling"

Projected Effects of Global Warming and the Resulting Changes in Global Climate

Global Cooling• Global cooling: natural• Planetary albedo – low, thick clouds reflect

sunlight, prevent warming• Volcanoes – dust reflect radiation• Sulfate aerosols – from pollutants, create

haze, reflecting sunlight

Kyoto Protocol• The Kyoto Protocol is the first international agreement

(UN) to fight global warming. • It set targets for nations to reduce greenhouse gas

(GHG) emissions .– 5% decrease against 1990 levels over the five-year

period 2008-2012. • It was signed by 141 nations, including all European and

all other developed industrial nations except the US and Australia. – Went into effect on February 16, 2005, and expires in

2012. • Pres. Clinton supported• Pres. Bush did not sign

Cap and Trade System• The goal: To steadily reduce carbon dioxide and

other greenhouse gas emissions economy-wide in a cost-effective manner.

• The cap: Each large-scale emitter, or company, will have a limit on the amount of greenhouse gas that it can emit.

• The trade: It will be cheaper or easier for some companies to reduce their emissions below their required limit than others. These more efficient companies, who emit less than their allowance, can sell their extra permits to companies that are not able to make reductions as easily.

• Output solutions– Massive global

tree planting; how many?• Wangari Maathai• Great Wall of

Trees: China and Africa

– Plant fast-growing perennials on degraded land

– Capturing and storing CO2

Fifteen Ways to Cut CO2 Emissions

We Can Prepare for the Harmful Effects of Climate Change

• Reduce greenhouse gas emissions as much as possible• Move people from low-lying coastal areas• Limit coastal building• Remove hazardous material storage tanks away from the

coast• Genetically engineer crops more tolerant to drought• Stockpile 1–5 years of key foods• Waste less water• Connect wildlife reserves with corridors

REVIEW• 1. Name the 5 greenhouse gases.• 2. What is the main greenhouse gas?• 3. Why is the greenhouse effect good for our planet?

Why is it harmful?• 4. Name 3 sources of CO2 and CH4.

• 5. Name 2 sinks for CO2.

• 6. List 5 effects of global warming.• 7. List 5 things you can do to reduce global warming.• 8. How can we prepare for global warming?• 9. Name the treaty that dealt with reducing

greenhouse gas emissions.• 10. Name 3 sources of global cooling.

• OO33

• Located in the stratosphereLocated in the stratosphere• Absorbs most of the UV light from the sunAbsorbs most of the UV light from the sun– UV light can cause genetic damage to living UV light can cause genetic damage to living

organisms- can cause skin cancer, faster aging, and organisms- can cause skin cancer, faster aging, and cataracts, cataracts, can kill one-celled organisms can kill one-celled organisms (phytoplankton) that live in the surface of the (phytoplankton) that live in the surface of the oceanocean, and interfere with photosynthesis, resulting , and interfere with photosynthesis, resulting in lower crop yieldsin lower crop yields

• The ozone in the stratosphere acts as a The ozone in the stratosphere acts as a sunscreen for Earth and its inhabitants.sunscreen for Earth and its inhabitants.

THE OZONE LAYER

OZONE EATERS• CFCs (Chlorofluorocarbons) – used in

refrigerants, air conditioners, styrofoam and propellants because they are chemically stable- they do not break down into other substances or combine with other substances.

• They are unreactive, odorless, nonflammable, nontoxic, noncorrosive and inexpensive to make.

• BUT, they do break apart in the stratosphere.

CFCs• CFCs that are

released in the troposphere can take 10-20 years to float into the stratosphere.

• One single chlorine atom can destroy 10,000 + ozone molecules and remain in the stratosphere 65-385 years!

The Ozone Hole• Depletion of the ozone layer allows more UV

light to reach the Earth’s surface

STOPPING THE OZONE EATERS75-85% of the ozone loss was from

CFCs and other ozone depleting chemicals• The Montreal Protocol – 1987

• The Copenhagen Protocol - 1992– Nations agreed to reduce their production of CFCsNations agreed to reduce their production of CFCs– US pledged to ban all substances that posed a US pledged to ban all substances that posed a

danger to the ozone layer by 2000danger to the ozone layer by 2000– Developed countries agreed to set up a fund to help Developed countries agreed to set up a fund to help

developing countries switch to CFC substitutesdeveloping countries switch to CFC substitutes

• CFCs remain active for more than 30 years, so it CFCs remain active for more than 30 years, so it will take decades for the layer to recover. will take decades for the layer to recover. THE NUMBER 1 SOURCE OF CFCs IS LEAKING AIR CONDITIONERS!

CFCs

• A greenhouse gas AND an ozone-depleting chemical.

• video clip• www.teachersdomain.org/asset/

ttv10_vid_ozone/s from Teacher’s Domain• http://http://www.teachersdomain.org/

asset/phy03_vid_greenhouse2/• http://www.teachersdomain.org/asset/

ttv10_vid_aerosols/

REVIEW1. In what layer of the earth’s atmosphere is the ozone layer?2. Why is the ozone layer beneficial?3. What is the main chemical that affects the ozone layer?4. Why was this chemical used in so many products?5. Name the treaty that was signed to decrease ozone depleting chemicals.6. What is the main source of CFC emissions?

• You fill your tank with 13 gallons of gas. How much CO2 will be produced by burning this amount of CO2?

• 13 gallons X 20 poundsCO2 = 260 pounds

1 gallon

How much CO2 is produced if you use 150 kWh of electricity in a month?

150 kWh x 2 pounds = 300 pounds CO2

1 kWh

• The average amount of CO2 per capita produced in America is 19.8 tons, which is 39, 600 pounds!