Why should we be concerned about Global Warming? Why should we be concerned about Global Warming?
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Transcript of Why should we be concerned about Global Warming? Why should we be concerned about Global Warming?
Why should we be concerned about Global Warming?
“Why should we be concerned about Global Warming?”
• Many people consider that Global Warming is the greatest environmental threat of the 21st Century.
• However, during the 80s and early 90s scientists argued about the causes and effects of global warming.
• In the late 1990s scientists reached a consensus that global warming was a cause for concern.
• So, why should you be concerned about global warming?
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 Gases
Nitrogen (N2)
Oxygen (O2)
Water (H2O)
Carbon Dioxide (CO2)
99%
Methane (CH4)
1%
Non-Greenhouse
Gases
GreenhouseGases
Sun Runaway Greenhouse EffectRunaway Greenhouse Effect
• 97% carbon dioxide• 3% nitrogen• Water & sulfuric
acid clouds• Temperature:
860°F
Venus
Carbon 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
Worldwide Carbon EmissionsWorldwide Carbon EmissionsC
arb
on
(10
9 m
etri
c to
ns)
0
1
2
3
4
5
6
7
8
1750 1800 1850 1900 1950 2000Year
Liquid fuelLiquid fuelTotalTotal
Gas fuelGas fuelSolid fuelSolid fuel
Annual Carbon EmissionsAnnual Carbon Emissions
Annual carbon emissionsAtmospheric CO2
Atmospheric CO2 average
1955 1965 1975 1985 1995 20050
4
6
8
2
Year
Car
bo
n (
109
met
ric
ton
s)
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)
Kyoto ProtocolKyoto Protocol
• Adopted in 1997
• Cut CO2 emissions by 5% from 1990 levels for 2008-2012
• Symbolic only, since cuts will not significantly impact global warming
Past 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
Winter Temperatures
10
11
12
13
14
15
16
17
1880 1900 1920 1940 1960 1980 2000
Year
Summer Temperatures
18
19
20
21
22
23
24
25
1880 1900 1920 1940 1960 1980 2000
Year
Annual Temperatures
15
16
17
18
19
20
21
22
1880 1900 1920 1940 1960 1980 2000
Year
Tem
per
atu
re (
°C)
Historic Los Angeles Temperatures
Historic Los Angeles Temperatures
-3 -2.5 -1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4
2007 Temperature Changes Compared to 1951-1980
2007 Temperature Changes Compared to 1951-1980
Past Temperatures MeasurementPast Temperatures Measurement
• Proxy – a method that approximates a particular measurement (e.g., temperature) 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!
Orbital Parameters & Earth’s ClimateOrbital Parameters & Earth’s Climate
Age (kya)1000900 800 700 600 500 400 300 200 100 0
Eccentricity(100 ky)
Temperature
Obliquity(41 ky)
Precession(22 ky)
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
YoungerDryas
YoungerDryas
Younger Dryas EventYounger Dryas Event
-55-55
-50-50
-45-45
-40-40
-35-35
-30-30
-25-25
05101520Age (kya)
Tem
per
atu
re (
°C)
Tem
per
atu
re (
°C)
0.050.05
0.100.10
0.150.15
0.200.20
0.250.25
0.300.30
0.350.35
Sn
ow
Acc
um
ula
tio
n (
m/y
r)S
no
w A
ccu
mu
lati
on
(m
/yr)
Little Ice AgeLittle Ice AgeIce Age
Medieval WarmMedieval Warm
Younger Dryas EventYounger Dryas Event
-44-44-43-43-42-42
-41-41-40-40-39-39-38-38-37-37
-36-36-35-35-34-34
18O
(G
reen
lan
d)
18O
(G
reen
lan
d)
-8.0-8.0
-7.5-7.5
-7.0-7.0
-6.5-6.5
-6.0-6.0
-5.5-5.5
-5.0-5.0
-4.5-4.5
-4.0-4.010111213141516
18O
(C
hin
a)18
O (
Ch
ina)
YoungerDryas
YoungerDryas
Age (kya)
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
“Hockey Stick” Controversey“Hockey Stick” Controversey
1000 1200 1400 1600 1800 2000-0.8
Year
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Tem
per
atu
re C
han
ge
(°C
)
Direct temperature measurementsMann et al. 1999
Mann et al. 1999Esper et al. 2002
800 1000 1200 1400 1600 1800-2
-1
0
1
2
Tem
per
atu
re C
han
ge
(°C
)
2000Year
Is the Hockey Stick Correct?Is the Hockey Stick Correct?
Is the Hockey Stick Correct?Is the Hockey Stick Correct?
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0 400 800 1200 1600 2000Year
Tem
per
atu
re C
han
ge
(°C
)
Mann et al. 1999Esper et al. 2002Moberg et al. 2005Mann et al. 2008
U.S. National Academy of Sciences: June 2006
U.S. National Academy of Sciences: June 2006
1000 1200 1400 1600 1800 2000-0.8
Year
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Tem
per
atu
re C
han
ge
(°C
)
“high level of confidence”“2:1 chance of being right”
-1.0
-0.5
0.0
0.5
1.0
1.5
1980 1990 2000Year
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1980 1990 2000Year
Tem
per
atu
re C
gan
ge
(°C
)
Atmospheric TemperaturesAtmospheric TemperaturesTroposphere Stratosphere
170170
220220
270270
320320
370370
00200000200000400000400000600000600000Time (YBP)Time (YBP)
CO
2 (p
pm
) A
nta
rcti
ca
CO
2 (p
pm
) A
nta
rcti
ca
2525262627272828292930303131
SS
T (
°C)
Tro
pic
al P
acif
icS
ST
(°C
) T
rop
ical
Pac
ific
CO2 Concentration Vs. TemperatureCO2 Concentration Vs. Temperature
Consequences 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
)
1920 1960 2000Year
Northern vs. Southern Latitude Land vs. Ocean
Northern HemisphereSouthern Hemisphere
LandOcean
2007 Temperature Changes Compared to 1951-1980
2007 Temperature Changes Compared to 1951-1980
-3 -2.5 -1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4
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
Changing Sea LevelsChanging Sea Levels
1700 1750 1800 1850 1900 1950 2000-20
-10
0
10
20
Rel
ativ
e S
ea L
evel
(cm
)
Adapted from IPCC SYR Figure 2-5
Amsterdam, NetherlandsBrest, FranceSwinoujscie, Poland
Glo
bal T
emp
erature C
han
ge
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
Cost to Stabilize CO2 Concentrations
Cost to Stabilize CO2 Concentrations
450 550 650 750
18001600140012001000
800600400200
0
Carbon Dioxide (ppm)
Co
st (
Tri
llon
s U
.S. D
olla
rs)
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
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?