chapter 20: the atmosphere, climate and global warming

Chapter 20:Chapter 20:

The Atmosphere, Climate and The Atmosphere, Climate and

Global WarmingGlobal Warming

OverviewOverview Fundamental Global Warming QuestionsFundamental Global Warming Questions Weather and ClimateWeather and Climate The Origin of the Global Warming IssueThe Origin of the Global Warming Issue The AtmosphereThe Atmosphere How We Study ClimateHow We Study Climate The Greenhouse EffectThe Greenhouse Effect The Major Greenhouse GasesThe Major Greenhouse Gases Climate Change and Feedback LoopsClimate Change and Feedback Loops Causes of Climate ChangeCauses of Climate Change The Oceans and Climate ChangeThe Oceans and Climate Change Forecasting Climate ChangeForecasting Climate Change Potential Rates of Global Climate ChangePotential Rates of Global Climate Change Potential Environmental, Ecological and Human Potential Environmental, Ecological and Human

Effects of Global WarmingEffects of Global Warming Adjusting to Potential Global WarmingAdjusting to Potential Global Warming

Fundamental Questions About Fundamental Questions About Global WarmingGlobal Warming

Concern arises from two pieces of Concern arises from two pieces of evidence:evidence: Increase in average surface Increase in average surface

temperature of the Earth from 1860 to temperature of the Earth from 1860 to the presentthe present

0.2˚C per decade since 19600.2˚C per decade since 1960 Increase in carbon dioxide Increase in carbon dioxide

concentrations in the atmosphereconcentrations in the atmosphere Measured on Mauna Loa in Hawaii by Measured on Mauna Loa in Hawaii by

Charles KeelingCharles Keeling

Fundamental Questions About Fundamental Questions About Global WarmingGlobal Warming What is the origin of rapid warming in the geologic What is the origin of rapid warming in the geologic

record?record? Is the present rapid warming unprecedented or at Is the present rapid warming unprecedented or at

least so rare that many living things will not be able least so rare that many living things will not be able to respond successfully to it?to respond successfully to it?

To what extent, have people caused it?To what extent, have people caused it? What are likely to be the effects on people?What are likely to be the effects on people? What are likely to be the effects on all life on Earth?What are likely to be the effects on all life on Earth? How can we make forecasts about it and other How can we make forecasts about it and other

kinds of climate change?kinds of climate change? What can we do to minimize potential negative What can we do to minimize potential negative

effects?effects?

Weather and ClimateWeather and Climate

WeatherWeather what’s happening now in the what’s happening now in the

atmosphere near the earth’s surfaceatmosphere near the earth’s surface Temperature, pressure, cloudiness, Temperature, pressure, cloudiness,

precipitation, windsprecipitation, winds

Climate is the average weatherClimate is the average weather Usually refers to long periods of timeUsually refers to long periods of time Classified mainly by latitude and Classified mainly by latitude and

wet/drywet/dry

The Climate is Always The Climate is Always ChangingChanging Climate has warmed and cooled may Climate has warmed and cooled may

times in Earth’s historytimes in Earth’s history Times of high temp involve relatively ice Times of high temp involve relatively ice

free periodsfree periods Times of low temp involve glacial eventsTimes of low temp involve glacial events

The Origins of the Global The Origins of the Global Warming IssueWarming Issue Relationship between chemistry of Relationship between chemistry of

planet’s atmosphere and planet’s planet’s atmosphere and planet’s surface temperaturesurface temperature Certain gases trap heat energy and Certain gases trap heat energy and

warm the planet warm the planet Since this idea was first introduce has Since this idea was first introduce has

stirred controversystirred controversy

The AtmosphereThe Atmosphere

Thin layer of gases that envelops EarthThin layer of gases that envelops Earth Held near the surface by gravitation and Held near the surface by gravitation and

pushed upward by thermal energy.pushed upward by thermal energy. Comprised ofComprised of

Nitrogen (78%)Nitrogen (78%) Oxygen (21%)Oxygen (21%) Argon (0.9%)Argon (0.9%) Carbon dioxide (0.03%)Carbon dioxide (0.03%) Water vaporWater vapor Trace amounts of other gases/pollutantsTrace amounts of other gases/pollutants

Dynamic systemDynamic system

Structure of the AtmosphereStructure of the Atmosphere

Made up of several vertical layersMade up of several vertical layers Troposphere - bottom layerTroposphere - bottom layer

Where weather occursWhere weather occurs Temperature decrease with elevationTemperature decrease with elevation At the top is tropopause - acts as a lidAt the top is tropopause - acts as a lid

Stratosphere - above the troposphereStratosphere - above the troposphere Stratospheric ozone layer just above the Stratospheric ozone layer just above the

tropopausetropopause Protects again UV radiationProtects again UV radiation

Atmospheric ProcessesAtmospheric Processes

Processes generally defined by Processes generally defined by pressure, temperature, and water pressure, temperature, and water vapor contentvapor content Pressure is force per unit areaPressure is force per unit area

Caused by the weight of overlying Caused by the weight of overlying atmospheric gases on those belowatmospheric gases on those below

Decreases with altitudeDecreases with altitude Low pressure systems usually bring cloudsLow pressure systems usually bring clouds High pressure systems usually bring clear High pressure systems usually bring clear

skiesskies


Temperature is the relative hotness or Temperature is the relative hotness or coldness of materialscoldness of materials

Measure of thermal energyMeasure of thermal energy Water vapor content is how much water Water vapor content is how much water

is in the gaseous formis in the gaseous form Varies from 1% to 4%Varies from 1% to 4%


Atmosphere moves due toAtmosphere moves due to Earth’s rotationEarth’s rotation Differential heatingDifferential heating

Produces global patterns of Produces global patterns of prevailing winds and latitudinal belts prevailing winds and latitudinal belts of high and low pressureof high and low pressure

What Makes What Makes the Earth the Earth WarmWarm Almost all the Almost all the

energy from the sunenergy from the sun Sunlight comes in a Sunlight comes in a

wide range of wide range of electromagnetic electromagnetic radiationradiation Long to short Long to short

wavelengthswavelengths Most of the radiation Most of the radiation

that reaches the that reaches the Earth is in the Earth is in the infrared and visible infrared and visible wavelengthswavelengths

What Makes the Earth WarmWhat Makes the Earth Warm

Under typical conditions Earth’s Under typical conditions Earth’s atmosphere:atmosphere: Reflects ~30% of the electromagnetic Reflects ~30% of the electromagnetic

energy that comes in from the sunenergy that comes in from the sun absorbs ~25%absorbs ~25% The remaining ~45% gets to the surface The remaining ~45% gets to the surface

Radiates back to the atmosphere or into Radiates back to the atmosphere or into outer spaceouter space

How We Study ClimateHow We Study Climate

Instrumental RecordsInstrumental Records Climate measurements began in 1860sClimate measurements began in 1860s Data from pre 19Data from pre 19thth century is century is

EstimatesEstimates ExtrapolatedExtrapolated InterpolatedInterpolated

We have very accurate data since 1960We have very accurate data since 1960 Improved instrumentationImproved instrumentation

How We Study ClimateHow We Study Climate

Historical RecordsHistorical Records Go back a few centuriesGo back a few centuries Mostly qualitativeMostly qualitative

Books, newspapers, journal articles, personal Books, newspapers, journal articles, personal journals, ships’ logs, travelers’ diaries, and farmers’ journals, ships’ logs, travelers’ diaries, and farmers’ logslogs

Paleoproxy recordsPaleoproxy records Proxy data- not strictly climatic, but provides Proxy data- not strictly climatic, but provides

insight into climateinsight into climate Tree rings, sediments, ice cores, fossil pollen, corals, Tree rings, sediments, ice cores, fossil pollen, corals,

and carbon‑14 (and carbon‑14 (1414C)C)

Proxy Climate RecordsProxy Climate Records

Ice cores have Ice cores have small bubbles of small bubbles of air air

Can measure Can measure carbon dioxide and carbon dioxide and methane levels methane levels from the time the from the time the ice was createdice was created

Ice CoresIce Cores Polar ice and mountain glaciers have ice Polar ice and mountain glaciers have ice

records that go back 100s or 1000s of records that go back 100s or 1000s of yearsyears

Oldest is 800,000 yearsOldest is 800,000 years

Proxy Climate RecordsProxy Climate Records Tree RingsTree Rings

Many trees Many trees create one create one growth ring per growth ring per yearyear

Width, density Width, density and ionic and ionic composition of composition of the ring are the ring are indicative of indicative of climateclimate

Proxy Climate RecordsProxy Climate Records

SedimentSediment Biological material (ex: pollen) is Biological material (ex: pollen) is

deposited on the land and stored for deposited on the land and stored for extended periods in lake, bog, and pond extended periods in lake, bog, and pond sedimentssediments

Pollen is usefulPollen is useful Quantity of pollen is an indicator of relative Quantity of pollen is an indicator of relative

abundance of each plant speciesabundance of each plant species Pollen can be datedPollen can be dated Can be used to construct a climate historyCan be used to construct a climate history

Proxy Climate RecordProxy Climate Record

CoralCoral Coral exoskeleton made of calcium Coral exoskeleton made of calcium

carbonatecarbonate Carbonate contains isotopes of oxygenCarbonate contains isotopes of oxygen Used to determine temp of water in which Used to determine temp of water in which

the coral grewthe coral grew

Proxy Climate RecordProxy Climate Record Carbon-14 and sun sunspotsCarbon-14 and sun sunspots

The Green House EffectThe Green House Effect

Each gas in the atmosphere has its Each gas in the atmosphere has its own absorption spectrumown absorption spectrum Certain gases are especially strong Certain gases are especially strong

absorbers in the infraredabsorbers in the infrared They absorb radiation emitted by the They absorb radiation emitted by the

warmed surfaces of the Earthwarmed surfaces of the Earth They then re-emit this radiationThey then re-emit this radiation This increases the temperature of the This increases the temperature of the

earth’s surfaceearth’s surface

The Green House EffectThe Green House Effect

Natural phenomenonNatural phenomenon Major greenhouse gases includeMajor greenhouse gases include

Water vaporWater vapor Carbon dioxideCarbon dioxide MethaneMethane Some oxides of Some oxides of nitrogennitrogen CFCsCFCs

Greenhouse EffectGreenhouse Effect

No one doubts that the greenhouse effect No one doubts that the greenhouse effect exists and affects planetsexists and affects planets

The puzzle arises on the Earth about The puzzle arises on the Earth about relative importance of greenhouse gases relative importance of greenhouse gases in affecting climatein affecting climate

Evidence indicates that carbon dioxide, Evidence indicates that carbon dioxide, methane, and temperature rise and fall methane, and temperature rise and fall togethertogether

Most scientists conclude that greenhouse Most scientists conclude that greenhouse gases are causing climate changegases are causing climate change

Positive and Negative Positive and Negative FeedbacksFeedbacks The atmosphere and its interactions The atmosphere and its interactions

w/ the ocean and land surfaces w/ the ocean and land surfaces experience positive and negative experience positive and negative feedbacksfeedbacks

Negative feedbackNegative feedback Warms temps warm air and lead to Warms temps warm air and lead to

increased evaporationincreased evaporation Evaporation leads to more cloud Evaporation leads to more cloud

formation which reflects more sunlight formation which reflects more sunlight which could cool the surface.which could cool the surface.

Positive and Negative Positive and Negative FeedbacksFeedbacks Positive feedbackPositive feedback

Warms temps warm air and lead to Warms temps warm air and lead to increased evaporation but instead of increased evaporation but instead of clouds forming remain as water vaporclouds forming remain as water vapor

Water vapor is a greenhouse gas. The Water vapor is a greenhouse gas. The warmer it gets the more water vapor, warmer it gets the more water vapor, and the process continuesand the process continues

Causes of Climate ChangeCauses of Climate Change 1919thth century century

Scientists began to understand that climate Scientists began to understand that climate changed greatly over long periods changed greatly over long periods

There were times of continental glaciationsThere were times of continental glaciations Evidence - debris at the edges of existing Evidence - debris at the edges of existing

glaciers which looked the same as those glaciers which looked the same as those deposited at lower elevationsdeposited at lower elevations

Cycles were apparentCycles were apparent 100,000 year cycles divided into 20,000–100,000 year cycles divided into 20,000–

40,000 year periods40,000 year periods

Causes of Climate ChangeCauses of Climate Change

Milankovitch CyclesMilankovitch Cycles Explain why climate changesExplain why climate changes Earth is like a wobbling top following Earth is like a wobbling top following

an elliptical orbit around the sunan elliptical orbit around the sun Three CyclesThree Cycles

1.1. 26,000 year26,000 year Earth Does not keep its poles at a constant Earth Does not keep its poles at a constant

angle in relation to the sunangle in relation to the sun Wobble around the pole makes a complete Wobble around the pole makes a complete

cycle in 26,000 yearscycle in 26,000 years


2.2. 41,000 years41,000 years The tilt of wobble also varies over a period The tilt of wobble also varies over a period

of 41,000 years of 41,000 years

3.3. 100,000 years100,000 years Elliptical orbit around the sun also changesElliptical orbit around the sun also changes Sometimes it is a more extreme ellipse; Sometimes it is a more extreme ellipse;

other times it is closer to a circle and this other times it is closer to a circle and this occurs over 100,000 years.occurs over 100,000 years.


The combination of these lead to The combination of these lead to periodic changes in the amount of periodic changes in the amount of sunlight reaching the Earthsunlight reaching the Earth Milankovitch showed that these Milankovitch showed that these

variations correlated with major glacial variations correlated with major glacial and interglacial periodsand interglacial periods

Don’t account for all climate Don’t account for all climate variationsvariations

Solar CyclesSolar Cycles

The Sun Goes Through Cycles The Sun Goes Through Cycles Sometimes hotter, sometimes coolerSometimes hotter, sometimes cooler Documented by differing amounts of Documented by differing amounts of

isotopes trapped in glacial iceisotopes trapped in glacial ice Variability of solar input of energy Variability of solar input of energy

explains some of the climatic explains some of the climatic variability toovariability too

Atmospheric Transparency Atmospheric Transparency Affects Climate and WeatherAffects Climate and Weather

Transparency of atmosphere to Transparency of atmosphere to radiation affects the temp of the radiation affects the temp of the EarthEarth From the sun coming inFrom the sun coming in From the Earth’s surface going outFrom the Earth’s surface going out

Dust and aerosols absorb lightDust and aerosols absorb light Volcanoes, forest fires and farming Volcanoes, forest fires and farming

put dust into the atmosphereput dust into the atmosphere Chemical and physical comp of Chemical and physical comp of

atmosphere can make it warmer or atmosphere can make it warmer or coolercooler

The Ocean’s Effect on Climate The Ocean’s Effect on Climate ChangeChange

Water has the highest heat capacity Water has the highest heat capacity of any compoundof any compound Large amount of heat energy is stored Large amount of heat energy is stored

in oceansin oceans Ocean absorbs dissolved COOcean absorbs dissolved CO22

As COAs CO22 increases in atmosphere it also increases in atmosphere it also increases in the oceansincreases in the oceans

The Ocean’s Effect on Climate The Ocean’s Effect on Climate ChangeChange Climate system driven (in part) by ocean Climate system driven (in part) by ocean

conveyor beltconveyor belt A global circulation of ocean watersA global circulation of ocean waters If the conveyor was shut down, major changes If the conveyor was shut down, major changes

in climate would occurin climate would occur

El Niño and ClimateEl Niño and Climate

El Niño refers to a specific periodic El Niño refers to a specific periodic variation of Pacific Ocean currentsvariation of Pacific Ocean currents

Under non-El Niño conditionsUnder non-El Niño conditions Trade-winds blow west across the Trade-winds blow west across the

tropical Pacifictropical Pacific Warm surface water pile up in Warm surface water pile up in

Western PacificWestern Pacific


During El Niño yearsDuring El Niño years Trade winds weakenTrade winds weaken Western moving current weakens or reversesWestern moving current weakens or reverses

As a result eastern equatorial ocean unusually As a result eastern equatorial ocean unusually warmwarm

High rates of precipitation and flooding in PeruHigh rates of precipitation and flooding in Peru

Changes global atmospheric circulationChanges global atmospheric circulation Causes changes in weather in regions that Causes changes in weather in regions that

are far removed from tropical Pacificare far removed from tropical Pacific


Surface water temperature rise off Surface water temperature rise off the South American coast inhibits the South American coast inhibits the upwelling of nutrient-rich cold the upwelling of nutrient-rich cold water from deeper levelswater from deeper levels Upwelling releases carbon dioxideUpwelling releases carbon dioxide El Niño events reduce the amount of El Niño events reduce the amount of

oceanic carbon outgassingoceanic carbon outgassing

Forecasting Climate ChangeForecasting Climate Change

Two ways to forecast the future:Two ways to forecast the future: Empirical and theoreticalEmpirical and theoretical

Empirical approach is to go back to Empirical approach is to go back to the geological idea of the geological idea of uniformitarianismuniformitarianism The past is the key to the futureThe past is the key to the future Has led to the extensive research on Has led to the extensive research on

climates and atmospheric conditions of climates and atmospheric conditions of the pastthe past

Predicting the Future of the Predicting the Future of the ClimateClimate Problem with Empirical approachProblem with Empirical approach

Temperature records are recent and not Temperature records are recent and not widespreadwidespread

Difficult to extrapolate, interpolate and Difficult to extrapolate, interpolate and estimateestimate

Hadley Meteorological Center in Great Hadley Meteorological Center in Great BritainBritain

Reconstructing temp recordsReconstructing temp records

Predicting the Future of the Predicting the Future of the ClimateClimate

Computer simulationComputer simulation General Circulation Models (GCM)General Circulation Models (GCM)

Based around the atmosphere being Based around the atmosphere being divided into rectangular solidsdivided into rectangular solids

Each a few km high and several km N or Each a few km high and several km N or SS

For each the flux of energy and matter is For each the flux of energy and matter is calculated to each adjacent cellcalculated to each adjacent cell

Steady state model - cannot account Steady state model - cannot account for randomnessfor randomness

Potential Rates of Global Climate Potential Rates of Global Climate ChangeChange

Global surface temp has increased Global surface temp has increased 0.2°C/ decade in the past 30 years.0.2°C/ decade in the past 30 years. Eight warmest years have occurred Eight warmest years have occurred

since 1997since 1997 Continued warming of 0.2°C /decade is Continued warming of 0.2°C /decade is

projected.projected.

Potential Rates of Global Climate Potential Rates of Global Climate ChangeChange

By 2030 By 2030 COCO22 concentration in the atmosphere concentration in the atmosphere

will have doubled from pre-Industrial will have doubled from pre-Industrial Revolution concentrationsRevolution concentrations

Average global temperature will have Average global temperature will have risen approximately 1° to 2°C risen approximately 1° to 2°C

Even greater temperature increases at polesEven greater temperature increases at poles Polar amplificationPolar amplification

Potential Effects of Global Potential Effects of Global WarmingWarming

Changes in River FlowChanges in River Flow Melting of glacial ice & reductions in Melting of glacial ice & reductions in

snow cover snow cover Rainfall will likely increase, but runoff will be Rainfall will likely increase, but runoff will be

more rapid than if snow slowly meltsmore rapid than if snow slowly melts Reservoirs will overflow - more water will Reservoirs will overflow - more water will

flow to the oceanflow to the ocean

Potential Effects of Global Potential Effects of Global WarmingWarming Rise in Sea LevelRise in Sea Level

Since last ice age, sea level has risen Since last ice age, sea level has risen 1 ft/century1 ft/century

Global warming could double thisGlobal warming could double this A major warming could increase sea A major warming could increase sea

levelslevels1.1. Expansion of liquid water as water warmsExpansion of liquid water as water warms

2.2. Melting of ice sheets on land whose waters Melting of ice sheets on land whose waters then flow into the oceanthen flow into the ocean

About half the people on Earth live on or About half the people on Earth live on or near the coast - vulnerable to floodingnear the coast - vulnerable to flooding

Potential Effects of Global Potential Effects of Global WarmingWarming Rise in sea level could: Rise in sea level could:

Threatens island nationsThreatens island nations Increase coastal erosion on open Increase coastal erosion on open

beaches and cause property loss.beaches and cause property loss. Cause landward progression of estuaries Cause landward progression of estuaries

and salt marshesand salt marshes Lead to lost of coastal wetlandsLead to lost of coastal wetlands Threaten ground water supply in coastal Threaten ground water supply in coastal

communitiescommunities

Tuvalu, the world’s smallest nation, may succumb to sea level riseTuvalu, the world’s smallest nation, may succumb to sea level rise

Potential Effects of Global Potential Effects of Global WarmingWarming Glaciers and Glaciers and

Antarctic Ice CapAntarctic Ice Cap Far more glaciers Far more glaciers

are retreating than are retreating than advancing advancing worldwideworldwide

Northern Northern Hemisphere sea ice Hemisphere sea ice coverage has coverage has declined an average declined an average of 10.7% per of 10.7% per decade since 1970sdecade since 1970s


The central ice cap on Antarctica is The central ice cap on Antarctica is growinggrowing This is consistent w/ prediction of global This is consistent w/ prediction of global

climate change modelsclimate change models As Earth warms, more snow falls on As Earth warms, more snow falls on

AntarcticaAntarctica The rate of melting of the Greenland The rate of melting of the Greenland

ice sheet has doubled since 1998ice sheet has doubled since 1998


Changes in Biological DiversityChanges in Biological Diversity The Intergovernmental Panel on Climate The Intergovernmental Panel on Climate

Change (IPCC) report states thatChange (IPCC) report states that ““approximately 2–20% of species assessed approximately 2–20% of species assessed

so far are likely to be at increased risk of so far are likely to be at increased risk of extinction as global mean temperatures extinction as global mean temperatures exceed a warming of 2 to 3°C above exceed a warming of 2 to 3°C above preindustrial levels.”preindustrial levels.”

Potential Effects of Global Potential Effects of Global WarmingWarming Black guillemotsBlack guillemots

Birds that nest on Cooper Island, Alaska,Birds that nest on Cooper Island, Alaska, The abundance of this species has The abundance of this species has

decreaseddecreased Recession of sea ice occurred before chicks Recession of sea ice occurred before chicks

were mature enough to survive on their ownwere mature enough to survive on their own Parent birds feed on Arctic cod found under the Parent birds feed on Arctic cod found under the

sea icesea ice Distance from feeding grounds to nest must be <30 Distance from feeding grounds to nest must be <30

kmkm In recent years - 250km to feeding groundsIn recent years - 250km to feeding grounds

Lost an important source of food for localsLost an important source of food for locals

Potential Effects of Global Potential Effects of Global WarmingWarming Agricultural Productivity-globallyAgricultural Productivity-globally

Likely to increase in some regions and Likely to increase in some regions and decline in othersdecline in others

Locations most likely negatively effectedLocations most likely negatively effected Mid-latitude food productionMid-latitude food production Lands in the southern part of the N. Lands in the southern part of the N.

Hemisphere Hemisphere May become more arid & soil moisture May become more arid & soil moisture

relationships will changerelationships will change

Human Health EffectsHuman Health Effects Difficult to forecastDifficult to forecast

Adjusting to Potential Global Adjusting to Potential Global WarmingWarming

Two types Two types AdaptAdapt

Learn to live with future global climatic Learn to live with future global climatic changechange

MitigateMitigate Work to reduce emissions of greenhouse Work to reduce emissions of greenhouse

gasesgases

Adjusting to Potential Global Adjusting to Potential Global WarmingWarming How can carbon dioxide emissions How can carbon dioxide emissions

be reduced?be reduced? Energy planning that relies heavily on Energy planning that relies heavily on

energy conservation and efficiencyenergy conservation and efficiency Use of alternative energy sources or Use of alternative energy sources or

natural gasnatural gas Use of mass transit Use of mass transit Greater economic incentives to energy-Greater economic incentives to energy-

efficient technologyefficient technology Higher fuel-economyHigher fuel-economy


Burning forests to convert land to Burning forests to convert land to agricultureagriculture Accounts for ~20% of anthropogenic emissions Accounts for ~20% of anthropogenic emissions

of carbon dioxideof carbon dioxide Reduce this by minimizing burning and Reduce this by minimizing burning and

protecting the world’s forests protecting the world’s forests ReforestationReforestation

Planting more treesPlanting more trees Increase biospheric sinks for carbon dioxideIncrease biospheric sinks for carbon dioxide


Geologic sequestration of carbon is Geologic sequestration of carbon is another possible mitigation measureanother possible mitigation measure Capture carbon dioxide from power Capture carbon dioxide from power

plants and industrial smokestacksplants and industrial smokestacks Compress the gas and change it to a Compress the gas and change it to a

mixture of both liquid and gas mixture of both liquid and gas Inject it deep undergroundInject it deep underground

Have the potential to sequester as much Have the potential to sequester as much as 1,000 gigatons of carbonas 1,000 gigatons of carbon

International Agreements to International Agreements to Mitigate Global WarmingMitigate Global Warming

Two major approachesTwo major approaches1.1. International agreements in which International agreements in which

each nation agrees to some specific each nation agrees to some specific limit on emissionslimit on emissions

2.2. Carbon tradingCarbon trading

Carbon TradingCarbon Trading

A nation or nation agrees to a cap of A nation or nation agrees to a cap of carbon emissionscarbon emissions Then corporations and other entities are Then corporations and other entities are

issued emission permits, allowing a issued emission permits, allowing a certain quantity of emissionscertain quantity of emissions

These can be tradedThese can be traded Overall nation does not exceed the capOverall nation does not exceed the cap


1988 1988 First international meeting to discuss First international meeting to discuss

limiting greenhouse gases held limiting greenhouse gases held (Toronto, Canada)(Toronto, Canada)

19921992 Earth Summit in Rio de Janeiro, Brazil.Earth Summit in Rio de Janeiro, Brazil. General blueprint for reduction of global General blueprint for reduction of global

emissions suggestedemissions suggested US thought it would be to costly and no US thought it would be to costly and no

legally binding limits setlegally binding limits set


19971997 Legally binding limits discussed in Legally binding limits discussed in

Kyoto, Japan.Kyoto, Japan. US eventually agreed to cut emissions US eventually agreed to cut emissions

to 7% below 1990 levels (leading to 7% below 1990 levels (leading scientists recommend cuts 60-80% scientists recommend cuts 60-80% below)below)

Became a formal treaty in 2006Became a formal treaty in 2006

chapter 20: the atmosphere, climate and global warming

Documents

global warmingconcern

global warmingwhat

wetdrythe climate

kinds of climate change

origin of rapid warming

cloudshigh pressure

altitudelow pressure

average surface temperature