Chapter 19 Global Warming & Ozone Loss © Brooks/Cole Publishing Company / ITP

Chapter 19Chapter 19Global Warming & Global Warming &

Ozone LossOzone Loss

© Brooks/Cole Publishing Company / ITP

Tuesday 3/29/11

1) Inconvenient Truth Review

2) Current Event – Global Warming & Coffee

3) Phet – Molecules & Light

4) Compare Global Warming & Ozone Loss

5) Sticky Analysis of CFCs & Skin Cancer

6) Compare Kyoto vs Montreal Protocols

Electromagnetic Spectrum

Black Body RadiationEarth radiation magnified 500x

Infrared Absorbance of CO2

Infrared Absorbance of Water

Infrared Absorbance of CH4

Infrared Absorbance of N2O

Absorbance Simulation of Gases

http://phet.colorado.edu/en/simulation/molecules-and-light



Table 18-1 Problem Comparison

Ozone depletion, skin cancers

Global warming, rising sea levels

What problems result?

CFCs, halons, CCl4, etc.

CO2, CH4, CFCs, N2O (nitrous oxide)

What are important human inputs?

Oxygen O2, ozone O3

H2O, CO2, CH4 (methane)

What natural gases are involved?

Filters ultraviolet (UV) radiation from the Sun

Traps infrared (IR) heat near surface

What process occurs?

Stratosphere 11-30 miles up

Troposphere 0-17 miles up

Where in the Atmosphere?

Ozone ShieldGreen House Effect

International Reports

• http://www.ipcc.ch/ipccreports/assessments-reports.htm

• IPCC Reports on Global Warning Issue

http://www.ipcc.ch/ipccreports/assessments-reports.htm

http://www.ipcc.ch/ipccreports/assessments-reports.htm

Activities

• Your Contribution to Global Warming

• Sea Level Rises – Topography

• An Inconvenient Truth

An Inconvenient Truth

It ain’t what you don’t know that gets you into trouble,

it’s what you know that just ain’t so.

Mark Twain

Green House Gases

1. What are greenhouse gases and what processes produce them?

• 80% CO2 – burning fossil fuels

• CH4, methane – livestock manure,

• N2O, nitrous oxide – fuel burning, crop & forest burning

• SF6, PFCs, HCFCs – industrial processes

Green House Effect2. How do greenhouse gases cause global

warming?• See page 28 & 29 of AIT• Solar energy reaches the Earth.• The Earth re-radiates some as infrared, IR.• Green house gases like CO2 absorb IR

before it escapes and hold the energy in the atmosphere.

• As green house gases accumulate in the atmosphere, more & more energy is trapped in the atmosphere.

Atmospheric CO2 Concentrations (1 of 2)

3. Scientists have measured atmospheric CO2 concentration from 1958 to today. What has been the trend in global atmospheric CO2 concentration over the past 50 years since scientists started directly measuring it?

• See page 36 & 37 • determine slope of steady increase• m = (380-315)ppm/ (2005-1958)yr • = 65/47 ppm/yr = 1.4 ppm/yr• 381ppm in 2005 vs 280 ppm baseline, % increase?• 381/280 = 136% or a 36% increase.

Atmospheric CO2 Concentrations (2 of 2)

3. Why does the line go up and down each year?

See pages 32-35• Most of the Earth’s land mass is in the Northern

Hemisphere.• During the Spring & Summer the Northern Hemisphere

draws in CO2 during its growing season.• During the Fall & Winter the Northern Hemisphere

releases CO2 as plants slow photosynthesis and a lot decomposes.

• The Southern Hemisphere has a much smaller effect.

Historical CO2 vs Temperature

4. What is the relationship between global atmospheric CO2 concentrations and mean global atmospheric temperature over the past 600,000 years? Gore says this is like the fit of South American and African continents; explain what he means by this.

• See page 66 & 67.• Antarctic ice core measurements show that global

temperatures closely mirror global CO2 levels.

Cyclical Pattern?5. Explain the evidence that suggests that the warming

period we are in is not just part of a "natural cyclical phenomenon".

• See page 64 & 65.• Over the last 1000 years, glacial ice cores show 3

previous warming periods, none of them compare to the present warming period in persistence or intensity.

• See page 67.• The present CO2 levels far exceed any CO2 levels

measured over the past 650,000 years and they continue to climb steeply.

Winston Churchill 1936

The era of procrastination, of half-measures, of soothing and baffling expedients, of delays, is coming to a close. In its place we are entering a period of consequences.

What was he talking about?

Hitler’s Nazi Invasions

How does this relate to global warming?

The consequences of global warming are already impacting our world.

Effects of Global Warming A. Melting of floating sea ice & impacts1. Minimal sea level change ( page 142 & 143)• Only 1/8 of sea ice is above the sea level.2. Polar bear populations (and others) page 147• Polar bears depend on diminishing ice pack for seal

hunting grounds. They are drowning at record rates.3. Acceleration of global warming due to changes in

sunlight reflection & absorption (see page 145)• Sea ice reflects sunlight and minimizes absorption.• Melted sea ice exposes sea water which absorbs

sunlight, heats up and melts the sea ice even faster in a __________ feedback loop.

OutlineOutline

1. Natural Global Processes• What is the greenhouse effect?• What is the ozone shield?

2. What Problems Result from Human Inputs• Global warming• Ozone depletion

3. Solutions

4. Summary


Fig. 18–3

pollution – undesirable change in physical, chemical, or biological characteristics of air, water, soil, or food that can adversely affect humans or other living organisms.


1. Natural Global Processes1. Natural Global Processes

• Greenhouse Effect

• Ozone Shield

• Questions

– What?

– Where?

– Gases involved?

– Human inputs?

– What problems result?


What is the Greenhouse Effect?What is the Greenhouse Effect?Greenhouse Effect: a natural process that traps heat near the Earth’s surface.

• short wave radiation in

• long waveradiation out

• re-radiationdownward by“greenhousegases” in atmosphere

© Brooks/Cole Publishing Company / ITPFig. 4–7

Fig. 19–2 c & d

Human inputs?Human inputs?(continued)(continued)

Greenhouse Effect:

• methane (CH4)

• nitrous oxide (N2O)


c) CH4

d) N2O

2. What Problems Result from 2. What Problems Result from Human Inputs?Human Inputs?

• Global Warming

• Ozone Depletion

• Questions

– Are they proven?

– What are potential consequences?

– What can be done?


•Sources of Increased Atmospheric CO2

– Burning Fossil Fuels

– Deforestation

•Carbon Balance: increased atmospheric CO2 less than expected based only on input

– about 49% remains in atmosphere

– about 29% uptake by oceans

– carbon balance: about 22% unaccounted for

(see Fig. 5–5)

How Does This Relate to How Does This Relate to the Carbon Cycle?the Carbon Cycle?


Fig. 19–6

Consequences of Increased Consequences of Increased Greenhouse GasesGreenhouse Gases


Climate Changes Climate Changes During Past 900,000 YearsDuring Past 900,000 Years

• Past climate based on study of Antarctic glaciers• Cycles of Ice Ages lasting about 100,000 years• Interglacial Periods lasting 10,000 to 12,500 yrs


Fig. 19–3

Fig. 19–4

• End of last ice age

about 10,000 yr BP

• Now in warm

interglacial period

• Based on ice core

data, analysis of

trapped gas

• Correlation between

CO2 & mean

temperature

Climate During Past 160,000 YearsClimate During Past 160,000 Years


Fig. 19–5

What is the Scientific Consensus?What is the Scientific Consensus?

• Mean global temperature rose about 0.6º C (1º F) in past 100 years

• Increase is real, not explained by natural variation in solar radiation

• Warming greater at poles than equator, greater at night, mostly troposphere


Fig. 19–5

Future ScenariosFuture Scenarios

General Circulation Models (GMCs) used to predict future climate

• Projected warming of 1 to 3.5 º C between 1990 & 2100

• Likely scenario: doubling of CO2 (from 280 ppm to 560 ppm) before 2100 leading to warming of 2º C


• Storage of CO2 in deep water

• Warming could decrease ability of ocean to serve as “sink” for carbon

Role of OceanRole of Ocean

Fig. 19–7 © Brooks/Cole Publishing Company / ITP

Fig. 19–8

Ecological ImplicationsEcological Implications

• Shift of habitat to higher latitudes

• Shift of habitat to higher elevations

• Potential large loss of biodiversity


Fig. 19–9

3. Solutions3. Solutions


Solutions to Global Warming

Fig. 19–10 © Brooks/Cole Publishing Company / ITP

Solutions to Global Warming

Fig. 19–2 a & b

Human inputs?Human inputs?

Greenhouse Effect:

• carbon dioxide (CO2)

– 75% developed countries

– 22% U.S.

• chlorofluorocarbons (CFCs)


a) CO2

b) CFCs

Where?Where?

• Greenhouse Effect:• in troposphere

• Ozone Shield:• in stratosphere 11-16

miles up

What is the Ozone Shield?What is the Ozone Shield?Ozone Shield: a natural process that filters

ultraviolet (UV) radiation before it reaches the lower atmosphere.

Human inputs?Human inputs?• Ozone Shield:• Chlorofluorocarbons (CFCs)• other stable halogen–containing gases (halogens =

chlorine, fluorine, & bromine)

b) CFCs

•Greenhouse Effect:

water carbon dioxide methane H2O CO2 CH4

•Ozone Shield: oxygen ozone O2 O3

What Natural Gases?What Natural Gases?


•CFCs stable, move from troposphere to stratosphere

•UV breaks off chlorine molecule (Cl) from CFC

•Cl acts as a catalyst to break down ozone (O3)

– catalyst – promotes a chemical reaction without itself being used up in the reaction

– shifts equilibrium of oxygen / ozone reaction: O2 O3

How Does Depletion Occur?How Does Depletion Occur?


Fig. 19–12

How Does Depletion Occur?How Does Depletion Occur?


Consequences of Ozone DepletionConsequences of Ozone Depletion

• Increase in skin cancer & cataracts, especially in southern hemisphere

• More ozone near earth’s surface, produced in photochemical smog – lung problems, suppressed immune response, cancer


What are the Consequences of What are the Consequences of Increased Increased

Ozone Depleting GasesOzone Depleting Gases

What are the Consequences of What are the Consequences of Ozone Depletion?Ozone Depletion?

• Increase in skin cancer & cataracts, especially in southern hemisphere

• More ozone near earth’s surface, produced in photochemical smog – lung problems, suppressed immune response, cancer

What is the Ozone Hole?What is the Ozone Hole?• Seasonal thinning of the ozone layer has

resulted at the poles, especially in the southern hemisphere.

• Recent models suggest the hole may not get larger.

Comparing Ozone LossComparing Ozone LossHow does the ozone loss over the North Pole compare to the South Pole?Projected total ozone loss, averaged over 2010-2019, during September for

the Antarctic (left) and during March for the Arctic (right). According to the model used to make these projections, during this period

the severity of ozone loss over the Arctic may approach that over the Antarctic.

Dark red represents ozone depletion of 54% or more; light blue, 18-30%; dark blue, 6-12%.

Solutions to Ozone DepletionSolutions to Ozone Depletion

• phase out use of ozone–depleting chemicals– halons, CFCs, methyl chloroform, methyl

bromide

• phase in use of CFC substitutes– non–halogen aerosol propellants,

hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), hydrocarbons (HCs), ammonia, water & steam, terpenes, helium

Summary Problem Comparison

Ozone depletion, skin cancers

Global warming, rising sea levels

What problems result?

CFCs, halons, CCl4, etc.

CO2, CH4, CFCs, N2O (nitrous oxide)

What are important human inputs?

Oxygen O2, ozone O3

H2O, CO2,

CH4 (methane)

What natural gases are involved?

Filters ultraviolet (UV) radiation from the Sun

Traps infrared (IR) heat near surface

What process occurs?

Stratosphere 11-30 miles up

Troposphere 0-11 miles up

Where in the Atmosphere?

Ozone ShieldGreen House Effect

Documents

Chapter 19 Global Warming & Ozone Loss © Brooks/Cole Publishing Company / ITP