Global Warming

Global WarmingGlobal WarmingWill Human-Induced Climate Change Destroy the World?

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IntroductionIntroduction

• Is the world getting warmer?

• If so, are the actions of mankind to blame for earth’s temperature increases?

• What can/should be done about these issues?

• Are the potential resolutions worth the cost to implement them?

History of Earth’s ClimateHistory of Earth’s Climate

• Earth formed ~4.6 billion years ago• Originally very hot• Sun’s energy output only 70% of

present• Liquid water present ~4.3 billion years

ago (zircon dating)• Much of earth’s early history erased

during late heavy bombardment (~3.9 billion years ago)

History of Earth’s ClimateHistory of Earth’s Climate

• Life appeared ~3.8 billion years ago• Photosynthesis began 3.5-2.5 billion

years ago Produced oxygen and removed carbon

dioxide and methane (greenhouse gases) Earth went through periods of cooling

(“Snowball Earth”) and warming

• Earth began cycles of glacial and interglacial periods ~3 million years ago

Sun

Earth’s TemperatureEarth’s Temperature

Solar

Energy

Solar

Energy

Solar

Energy

Solar

Energy

Sun

Earth’s TemperatureEarth’s Temperature

Solar

Energy

Solar

Energy

RadiativeCooling

RadiativeCooling

Sun

Earth’s TemperatureEarth’s Temperature

Solar

Energy

Solar

Energy

RadiativeCooling

RadiativeCooling

Sun

Earth’s TemperatureEarth’s Temperature

Solar

Energy

Solar

Energy

RadiativeCooling

RadiativeCooling

Greenhouse EffectGreenhouse EffectSun

Earth’s Atmospheric GasesEarth’s Atmospheric GasesNitrogen (N2)

Oxygen (O2)

Water (H2O)

Carbon Dioxide (CO2)

>99%

Methane (CH4)

<1%

Non-Greenhouse

Gases

GreenhouseGases

Argon (Ar)

Sun Runaway Greenhouse EffectRunaway Greenhouse Effect

• 97% carbon dioxide• 3% nitrogen• Water & sulfuric

acid clouds• Temperature:

860°F

Venus

Carbon DioxideCarbon Dioxide

170

220

270

320

370

420

200000400000600000Time (YBP)

CO

2 (p

pm

)

Vostok Ice CoreDome Concordia

Carbon Dioxide LevelsCarbon Dioxide Levels

0

Muana Loa ReadingsCO2 Levels Since 1958

310330350370

10203040

CO

2 (

pp

m)

0

Future Carbon Dioxide LevelsFuture Carbon Dioxide Levels

• Increasing CO2 emissions, especially in China and developing countries

• Likely to double within 150 years: Increased coal usage Increased natural gas usage Decreased petroleum usage (increased

cost and decreasing supply)

Past TemperaturesPast Temperatures

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1880 1900 1920 1940 1960 1980 2000Year

M

ean

Tem

per

atu

re (

°C)

Recorded Worldwide Temperatures

Recorded Worldwide Temperatures

FlatDecreasing

Flat

2009 Temperature Changes Compared to 1951-1980

2009 Temperature Changes Compared to 1951-1980

-4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1

2009 Temperature Changes Compared to 1951-1980

Past Temperatures MeasurementPast Temperatures Measurement

• Proxy – a method that approximates a particular measurement (e.g., temperature) Tree rings Ice cores Pollen records Plant macrofossils Sr/Ca isotope data Oxygen isotopes from speleothem calcite

(stalactites and stalagmites)

Temperature History of the EarthTemperature History of the Earth• Little ice age (1400-1840) – 1°C cooler • Medieval warm period (800-1300) – 1°C

warmer than today• Cool/warm cycles occur ~1,500 years• Affect mostly Northeastern U.S. and North

Atlantic• Mostly due to changes in thermohaline

circulation • Dramatic shutdown of thermohaline

circulation occurred 8,200 years ago as a large lake in Canada flooded the North Atlantic

Main Ocean CurrentsMain Ocean Currents

Adapted from IPCC SYR Figure 4-2

Temperature History of the EarthTemperature History of the Earth

• For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods

• These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity

Orbital Parameters: PrecessionOrbital Parameters: Precession

PerihelionApehelion

Orbital Parameters: ObliquityOrbital Parameters: Obliquity22.5°24.5°

Orbital Parameters: EccentricityOrbital Parameters: Eccentricity

PerihelionApehelionApehelion

Minimum: 0.005Minimum: 0.005

Maximum: 0.061Maximum: 0.061

Not to scale!Not to scale!To Scale!To Scale!

Temperature History of the EarthTemperature History of the Earth

• For the past 3 million years, the earth has been experiencing ~100,000 year long cycles of glaciation followed by ~10,000 year long interglacial periods

• Last ice age began to thaw 15,000 years ago, but was interrupted by the “Younger Dryas” event 12,900 years ago

Temperature History of the EarthTemperature History of the Earth

Middle Pliocene (3.15 to 2.85 million ya)

• Temperatures: 2°C higher than today. 20°C higher at high latitudes 1°C higher at the Equator

• Sea levels were 100 ft higher

• Causes CO2 levels that were 100 ppm higher

Increased thermohaline circulation

Temperature History of the EarthTemperature History of the Earth

Eocene (41 million years ago)

• Opening of the Drake Passage (between South America and Antarctica).

• Increased ocean current exchange Strong global cooling First permanent glaciation of Antarctica

~34 million years ago

Temperature History of the EarthTemperature History of the Earth

Paleocene Thermal Maximum (55 mya)

• Sea surface temperatures rose 5-8°C

• Causes Increased volcanism Rapid release of methane from the oceans

Temperature History of the EarthTemperature History of the Earth

Mid-Cretaceous (120-90 mya)

• Much warmer

• Breadfruit trees grew in Greenland

• Causes Different ocean currents (continental

arrangement) higher CO2 levels (at least 2 to 4 times

higher than today, up to 1200 ppm)

Recent Temperature Changes

Recent Temperature Changes

What Influences Tree Rings?What Influences Tree Rings?

• Temperature

• Rainfall

• Carbon dioxide concentration

Consequences of Global Warming

Consequences of Global Warming

2009 Temperature Changes Compared to 1951-1980

2009 Temperature Changes Compared to 1951-1980

-4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1

Ice Sheets Melting?Ice Sheets Melting?

• GRACE (gravity measured by satellite) found melting of Antarctica equivalent to sea level rise of 0.4 mm/year (2 in/century)

• Zwally, 2005 (satellite radar altimetry) confirmed Antarctica melting Greenland ice melting on

exterior, accumulating inland(higher precipitation)

Melting Glaciers – Mt. KilimanjaroMelting Glaciers – Mt. Kilimanjaro

1000

800

600

400

200

0

-200

-400

-6002003 2004 2005

Ice

Mas

s (k

m3 )

Year

Changes in Antarctica Ice Mass Changes in Antarctica Ice Mass

Rise in Sea Levels?Rise in Sea Levels?

• Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century)

• Accelerating at a rate of 0.013 ± 0.006 mm/yr2

• If acceleration continues, could result in 12 in/century sea level rise

• Scenarios claiming 1 meter or more rise are unrealistic

Time (KYBP)Time (KYBP)

Sea

Lev

el (

m)

Sea

Lev

el (

m)

2020

00

-20-20

-40-40

-60-60

-80-80

-100-100

-120-120

Sea Levels for 450,000 YearsSea Levels for 450,000 Years

450450 400400 350350 300300 250250 200200 150150 100100 5050 002525

2626

2727

2828

2929

3030

3131

SS

T (

°C)

Tro

pic

al P

acif

icS

ST

(°C

) T

rop

ical

Pac

ific

Increase in Hurricanes?Increase in Hurricanes?

• Two studies showed the total number of hurricanes has not changed

• However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones)

• Probably due to higher sea surface temperatures (more energy)

• Difficult to know if this trend will continue

• Two studies showed the total number of hurricanes has not changed

• However, the intensity of hurricanes has increased (more category 4 and 5 hurricanes and cyclones)

• Probably due to higher sea surface temperatures (more energy)

• Difficult to know if this trend will continue

18601860 18801880 19001900 19201920 19401940 19601960 19801980 20002000 2020202000

55

1010

1515

Data UnreliableData Unreliable

Scaled August-OctoberSea-Surface TemperatureAdjusted Atlantic StormPower Dissipation Index

Scaled August-OctoberSea-Surface TemperatureAdjusted Atlantic StormPower Dissipation Index

SS

T/S

PD

I (m

eter

s3 /se

c2 )S

ST

/SP

DI (

met

ers3 /

sec2 )

How Much Temperature Increase?

How Much Temperature Increase?

• Some models propose up to 9°C increase this century

• Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C

• Another study puts the minimum at 2.5°C

Wildlife EffectsWildlife Effects

• Polar Bears Require pack ice to live Might eventually go extinct in the wild

• Sea turtles Breed on the same islands as

their birth Could go extinct on some islands

as beaches are flooded

• Other species may go extinct as rainfall patterns change throughout the world

• Polar Bears Require pack ice to live Might eventually go extinct in the wild

• Sea turtles Breed on the same islands as

their birth Could go extinct on some islands

as beaches are flooded

• Other species may go extinct as rainfall patterns change throughout the world

Effect on HumansEffect on Humans

• Fewer deaths from cold, more from heat

• Decreased thermohaline circulation Cooler temperatures in North Atlantic

• CO2 fertilization effect

• Precipitation changes Droughts and famine (some areas) Expanded arable land in Canada, Soviet Union

Potential Worldwide Precipitation Changes

Potential Worldwide Precipitation Changes

-50 -20 -10 -5 5 10 20 50

Drought in AfricaDrought in Africa

Lake FaguibineLake Faguibine Lake ChadLake Chad

Possible Solutions to Global Warming

Possible Solutions to Global Warming

Mitigation of Global WarmingMitigation of Global Warming

• Conservation Reduce energy needs Recycling

• Alternate energy sources Nuclear Wind Geothermal Hydroelectric Solar Fusion?

Storage of CO2 in Geological FormationsStorage of CO2 in Geological Formations

1. Depleted oil and gas reservoirs

2. CO2 in enhanced oil and gas recovery3. Deep saline formations – (a) offshore (b) onshore

4. CO2 in enhanced coal bed methane recovery

1. Depleted oil and gas reservoirs

2. CO2 in enhanced oil and gas recovery3. Deep saline formations – (a) offshore (b) onshore

4. CO2 in enhanced coal bed methane recovery

Adapted from IPCC SRCCS Figure TS-7

3a3a22

3b3b 11 44

Global Warming MythsGlobal Warming Myths

-4.1 -4 -2 -1 -.5 -.2 .2 .5 1 2 4 4.1

Global Warming is Due to Urban Heat Islands

Global Warming is Due to Urban Heat Islands

2009 Temperature Changes Compared to 1951-1980

Mt. Kilimanjaro’ Glaciers are Melting Because of Global Warming

Mt. Kilimanjaro’ Glaciers are Melting Because of Global Warming

Global Warming Primarily Impacts the Northern Hemisphere

Global Warming Primarily Impacts the Northern Hemisphere

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1920 1960 2000Year

Tem

pera

ture

Cha

nge

(°C

)

Northern vs. Southern Latitude

Northern HemisphereSouthern Hemisphere

1920 1960 2000Year

Land vs. Ocean

LandOcean

Sea Levels Will Rise 5-6 ft?Sea Levels Will Rise 5-6 ft?

• Present rate is 1.8 ± 0.3 mm/yr (7.4 in/century)

• Accelerating at a rate of 0.013 ± 0.006 mm/yr2

• If acceleration continues, could result in 12 in/century sea level rise

• Scenarios claiming 1 meter or more rise are unrealistic

• Recently, the California State Lands Commission said that sea levels could rise 55 inches this century, inundating ports

How Much Temperature Increase?

How Much Temperature Increase?

• Global warming alarmists propose up to 9°C increase this century

• Two studies put the minimum at 1.5°C and maximum at 4.5°C or 6.2°C

• Another study puts the minimum at 2.5°C

Temperature ExtrapolationTemperature ExtrapolationT

(°C

)1.5

1.0

0.5

0

-0.4

Date1980 2000 2020 2040 2060 2080 2100

2.5

2.0

1960

ConclusionsConclusions

• Global warming is happening

• Most warming is probably the result of human activities

• There will be positive and negative (mostly) repercussions from global warming

• The costs to mitigate global warming will be high – better spent elsewhere?