Global Climate Change for Beginners Global Climate Change for Beginners

Robert K. Kaufmann

July 7, 2008

http://www.bu.edu/cees/people/faculty/kaufmann/index.html

Surface TemperatureSurface Temperature

Climate vs. WeatherClimate vs. Weather

Weather: Conditions on any given dayTemperature in Boston today is 91oF

Climate: Average conditions on any given day over The average temperature in Richmond on

July 7, is 83oF

15,000 Years of Temperature15,000 Years of Temperature

1000 Years of Temperature1000 Years of Temperature

Instrumental Temperature RecordInstrumental Temperature Record

Heat Balance of Planet EarthHeat Balance of Planet Earth

Changes in Out-Going RadiationChanges in Out-Going Radiation

Radiative Forcing of Sulfur EmissionsRadiative Forcing of Sulfur Emissions

Direct Effect

The Heat Balance of Planet EarthThe Heat Balance of Planet Earth

Ground

SOx

The Heat Balance of Planet EarthThe Heat Balance of Planet Earth

Ground

SOx

Clouds

The Vostok RecordThe Vostok Record

From: Petit et al., Nature 399, 429 - 436 (1999

How Do Humans Affect Radiative How Do Humans Affect Radiative Forcing?Forcing?

Burning Fossil FuelsBurning Fossil Fuels

Changing Land-UseChanging Land-Use

DeforestationChopping down trees releases carbon dioxideIncreasing termite habitat methane emissions

AgricultureRice paddies--human swamps emit methaneLivestock--Methane ‘burps’

Human Sources of Carbon DioxideHuman Sources of Carbon Dioxide

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Fossil Fuel

Deforestation

Humans are Not the Largest Humans are Not the Largest

Source of Carbon Dioxide Source of Carbon Dioxide

http://en.sevenload.com/videos/ha4PoKY/The-Great-Global-Warming-Swindle

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The Global Carbon Cycle The Global Carbon Cycle

Atmospheric ConcentrationsAtmospheric Concentrations

Detection: Is Climate Changing?Detection: Is Climate Changing?

Earlier Springs, Later AutumnsEarlier Springs, Later Autumns

Rising Sea LevelsRising Sea Levels

Figure 5.13

Attribution: Are Humans Responsible Attribution: Are Humans Responsible for Climate Change?for Climate Change?

Model ResultsModel Results

Statistical Analysis of Historical DataStatistical Analysis of Historical Data

How Much How Much Doubt Really Exists?Doubt Really Exists?

“If rising carbon dioxide is the cause of rising temperatures, why didn’t it cause temperatures to rise from 1940 to 1970?

“Trust me, the satellite data have been reanalyzed dozens of times,…they show much less warming than expected by theory

Solar Activity is to BlameSolar Activity is to Blame

http://en.sevenload.com/videos/ha4PoKY/The-Great-Global-Warming-Swindle

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Solar ActivitySolar Activity

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-0.4

-0.2

0

0.2

0.4

0.6

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1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Solar Activity watts/m2 (Lean et al., 1995),

No Relationship Between CarbonNo Relationship Between CarbonDioxide and TemperatureDioxide and Temperature

http://en.sevenload.com/videos/ha4PoKY/The-Great-Global-Warming-Swindle

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Remember Sulfur Aerosols!Remember Sulfur Aerosols!

Climate Models: How, Where, and By Climate Models: How, Where, and By How Much Will Climate Change?How Much Will Climate Change?

Causes For Temperature ChangeCauses For Temperature Change

Doubling of radiative forcing……………1.2oCIncreased water vapor……….. ……….1.6oCIncrease in clouds………………………..0.8oCChanges in surface albedo……………….0.4oCOther changes……………………………0.2oC

Total change in temperature…………….4.2oC

Climate change impacts on the Climate change impacts on the environment & economyenvironment & economy

Change in sea levelImpact on agricultureImpact on biomesWater Supply

Changes in Sea LevelChanges in Sea Level

Melting of glaciers and polar ice

Thermal expansion of water

Florida 11.8 Thousand Years AgoFlorida 11.8 Thousand Years Ago

Florida 5 Meter Sea Level RiseFlorida 5 Meter Sea Level Rise

Florida 50 Meter Sea Level RiseFlorida 50 Meter Sea Level Rise

Impacts on AgricultureImpacts on Agriculture

Benefits Costs

Longer growing season

CO2 Fertilization

Mid Continent Drying

Warmer nights

Water use efficiency

Can Biomes Migrate in Time?Can Biomes Migrate in Time?

Climate ChangeClimate Change & Extinction& Extinction

Thomas et al, 2004 Nature 427:145-148.

Migration rate Minimum Middle High

Universal dispersal 9-13 15-20 21-32No dispersal 22-31 26-37 38-52

Climate change scenario

By How Much Should Carbon By How Much Should Carbon Emissions Be Reduced?Emissions Be Reduced?

What does society “give up”

What does society gain?

Command & Control Command & Control

BenefitsPoliticians can measure their effectsInvisible taxesReductions known

CostsMay not be least costNo incentive for further reductionsNo incentive for technical developmentCumbersome

Carbon Taxes Carbon Taxes

Tax reflects the marginal damage of carbon emissions

Higher cost reduces emissionsReplace energy use with capital or laborReplace high carbon fuels with low carbon fuels

Tax rate based on carbon content of fuel ($100 ton)Gasoline ($1.00 per gallon) $2.80 per gallonNatural gas ($6.00 per tcf) $12.91 per tcfCoal ($100 per ton) $55 per tonElectricity ($0.11 per Kwh) $0.11 per Kwh

Carbon Taxes Carbon Taxes

AdvantagesLeast cost reductionCost is well knownConstant incentive to reduce emissionsConstant incentive to improve technologyEasy to implement

DisadvantagesReductions are not well knownTaxes Kiss of death

Tradable PermitsTradable Permits

AdvantagesReductions well knownLeast cost reductionConstant incentive to reduce emissionsConstant incentive to improve technologyProven to work well (US sulfur market)

DisadvantagesCost of permit unknownStrong institutionsGood governance

Carbon OffsetsCarbon Offsets

Commercial providersBoston-Nashville round trip 2,043 milesEmissions 1,009 pounds carbon$9.95 in OffsetsOffsets reduce emissions elsewhere