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Our Changing AtmosphereOur Changing Atmosphere

The Earth’s surface The Earth’s surface temperature has temperature has risen by about 1 risen by about 1 deg. F. in the past deg. F. in the past centurycentury

Strong evidence Strong evidence suggests that suggests that warming is warming is attributable to attributable to human activitieshuman activities

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Greenhouse EffectGreenhouse Effect

Energy from the Energy from the sun drives the sun drives the earth’s climateearth’s climate

Greenhouse effect Greenhouse effect maintains livable maintains livable temperaturetemperature

Problems arise Problems arise when when concentrations concentrations increaseincrease

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

http://www.teachersdomain.org/assethttp://www.teachersdomain.org/asset/phy03_vid_co2//phy03_vid_co2/

co2 experimentco2 experiment

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Our Changing AtmosphereOur Changing Atmosphere

Humans are emitting Humans are emitting more greenhouse gases more greenhouse gases into the atmosphereinto the atmosphere

Cars, trucks, home and Cars, trucks, home and business business heating/cooling, and heating/cooling, and power factories(40%) power factories(40%) are responsible for are responsible for about 98% of US carbon about 98% of US carbon dioxide emissionsdioxide emissions

… … leads toleads to“Enhanced” Greenhouse Effect…“Enhanced” Greenhouse Effect…

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Since the Since the industrial industrial revolution, revolution, greenhouse greenhouse gases have gases have increased by:increased by:

Carbon Dioxide Carbon Dioxide 30%30%

Methane Methane 100%100%

Nitrous Oxide Nitrous Oxide 15%15%

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Our Changing ClimateOur Changing Climate

Global mean Global mean surface surface temperatures have temperatures have increased 0.5-1.0 increased 0.5-1.0 deg F since late deg F since late 1919thth century century

The 20The 20thth century’s century’s 10 warmest years 10 warmest years have occurred in have occurred in the last 15 years the last 15 years of the centuryof the century

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420,000 years of Ice core data420,000 years of Ice core data

… … support support the link the link between CObetween CO22 and and TemperatureTemperature

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So what happens to the Earth?So what happens to the Earth?

Climate is a complex conundrum, Climate is a complex conundrum, with many inter-related factors…with many inter-related factors…

Thus we use computer models to Thus we use computer models to make predictions:make predictions:• Rise in sea levels (due to volumetric Rise in sea levels (due to volumetric

expansion of warmer water V=Vexpansion of warmer water V=VooβΔβΔT, T, and the melting of land ice in Greenland, and the melting of land ice in Greenland, Antarctica, glaciersAntarctica, glaciers

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So what happens to the Earth?So what happens to the Earth?

• Weather changes (difficult to predict): Weather changes (difficult to predict): equatorial regions get hotter, Northern equatorial regions get hotter, Northern hemisphere gets wetter, hemisphere gets wetter,

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Industrialized World…Industrialized World…

Is 33% of world’s populationIs 33% of world’s population Uses 80% of world’s total energyUses 80% of world’s total energy

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You and I (in the USA):You and I (in the USA):

Are 5% of worlds’ populationAre 5% of worlds’ population Use 33% of worlds’ total energyUse 33% of worlds’ total energy

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Compared to India:Compared to India:

is 15% of world’s populationis 15% of world’s population Uses 1% of worlds’ total energyUses 1% of worlds’ total energy

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Compared to India:Compared to India:

USA uses USA uses moremore energy just for air energy just for air conditioning than…conditioning than…

India uses for ALL of their energy India uses for ALL of their energy purposes (5 times more people)purposes (5 times more people)

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Who’s most responsible?Who’s most responsible?

Emissions per American Emissions per American have increased about have increased about 3.4% between 1990 and 3.4% between 1990 and 19971997

Most of these emissions, Most of these emissions, about 82%, are from about 82%, are from burning fossil fuels to burning fossil fuels to generate electricity and generate electricity and power our carspower our cars

Remaining emissions are Remaining emissions are from methane from from methane from wastes in our landfills, wastes in our landfills, raising livestock, natural raising livestock, natural gas pipelines, and coalgas pipelines, and coal

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International EffortInternational Effort

1988: IPCC formed (Intergovernmental 1988: IPCC formed (Intergovernmental Panel on Climate Change) Panel on Climate Change) Its role is to openly and Its role is to openly and objectively assess the latest scientific, technical and socio-economic literature objectively assess the latest scientific, technical and socio-economic literature produced worldwide relevant to the understanding of the risk of human-induced produced worldwide relevant to the understanding of the risk of human-induced climate change, to provide the decision-makers and others interested in climate climate change, to provide the decision-makers and others interested in climate

change with an objective source of information about climate changechange with an objective source of information about climate change on a on a comprehensive, objective, open and transparent basis comprehensive, objective, open and transparent basis

1992-2007: Kyoto Protocol 1992-2007: Kyoto Protocol Treaty(ratifying countries committed to Treaty(ratifying countries committed to reduce greenhouse gases to 5% below reduce greenhouse gases to 5% below 1990 levels by 2012. 177 countries 1990 levels by 2012. 177 countries ratified… not US, Australia)ratified… not US, Australia)

2020

2005 APPCDC (Asia-Pacific 2005 APPCDC (Asia-Pacific Partnership on Clean Development Partnership on Clean Development and Climate)… non-treaty agreement and Climate)… non-treaty agreement amongst the 6 countries that account amongst the 6 countries that account for 50% of gg emissions… to develop for 50% of gg emissions… to develop and share technology to reduce and share technology to reduce global warming global warming AustraliaAustralia, , CanadaCanada, , IndiaIndia, , JapanJapan, , the the People's Republic of ChinaPeople's Republic of China, , South KoreaSouth Korea, and the , and the

United StatesUnited States

International EffortInternational Effort

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““average citizens can make valuable average citizens can make valuable contributions by making small lifestyle contributions by making small lifestyle

changes without waiting for governments to changes without waiting for governments to act”:act”:

Use less energy Use less energy (and use renewables)(and use renewables) • ↑ ↑ efficiency of electric power productionefficiency of electric power production

• Heat homes with excess power station heat,use hybrid/electric vehicles, Heat homes with excess power station heat,use hybrid/electric vehicles,

Capture COCapture CO22 (plant trees!) (plant trees!)

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UncertaintiesUncertainties

Human activities are changing the composition of Human activities are changing the composition of the atmospherethe atmosphere

Carbon Dioxide, Methane, and Nitrous Oxide have Carbon Dioxide, Methane, and Nitrous Oxide have increased as a result of human activitiesincreased as a result of human activities

Greenhouse gases trap heat in the earth’s Greenhouse gases trap heat in the earth’s atmosphere and tend to warm the planetatmosphere and tend to warm the planet

The key greenhouse gases emitted by human The key greenhouse gases emitted by human activities remain in the atmosphere for decades activities remain in the atmosphere for decades to centuriesto centuries

A warming trend of about 1 deg. F has been A warming trend of about 1 deg. F has been recorded since the late 19recorded since the late 19thth century century

What Is Known For Certain

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UncertaintiesUncertainties

What extent has the human-induced What extent has the human-induced accumulation of greenhouse gases are accumulation of greenhouse gases are responsible for the global warming trendresponsible for the global warming trend

For instance, scientific understanding of other For instance, scientific understanding of other factors are not know, such as natural climatic factors are not know, such as natural climatic variations, changes in the sun’s energy, and the variations, changes in the sun’s energy, and the cooling effects of pollutant aerosols is incompletecooling effects of pollutant aerosols is incomplete

What Is Likely, But Not Certain

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UncertaintiesUncertainties

Projecting the impacts to Health, agriculture, Projecting the impacts to Health, agriculture, water resources, forests, wildlife and coastal water resources, forests, wildlife and coastal areas in regional areas is very difficultareas in regional areas is very difficult

Large–scale areas are more suited to global Large–scale areas are more suited to global warming computer modelswarming computer models

Links to Global Warming and El NinoLinks to Global Warming and El Nino

What Are The Big Unknowns

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UncertaintiesUncertainties

How much warming will occur?How much warming will occur? How fast will this warming occur?How fast will this warming occur? What are the potential adverse and beneficial What are the potential adverse and beneficial

effects?effects?

These uncertainties will be with us for some time, These uncertainties will be with us for some time, perhaps decadesperhaps decades

What Are the Big Unknowns Contd…

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SummarySummary

There are many unknowns to global There are many unknowns to global warmingwarming

There are some things that are There are some things that are known howeverknown however

The science points to continued The science points to continued warmingwarming

Nothing is certainNothing is certain