internal structure and geological history internal structure of mercury, mars, and the moon,...
TRANSCRIPT
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Internal Structure and Geological History
Internal structure of Mercury, Mars, and the Moon, compared to Earth
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Atmospheric Evolution on Earth, Venus, and Mars
At formation, planets had primary atmosphere – hydrogen, helium, methane, ammonia, water vapor – which was quickly lost.
Secondary atmosphere – water vapor, carbon dioxide, sulfur dioxide, nitrogen – comes from volcanic activity.
Earth now has a tertiary atmosphere, 20 percent oxygen, due to the presence of life.
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Earth has a small greenhouse effect; it is in equilibrium with a comfortable (for us) surface temperature.
Atmospheric Evolution on Earth, Venus, and Mars
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Atmospheric Evolution on Earth, Venus, and Mars
Venus’s atmosphere is much denser and thicker; a runaway greenhouse effect has resulted in its present surface temperature of 730 K.
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The Habitable Zone or “The Goldilocks Problem”In the zone …
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Earth's Atmosphere
78% Nitrogen21% Oxygen
gas is ionized by solar radiation
ozone is O3 , which
absorbs solar UV efficiently, thusheating stratosphere
commercial jet altitudes
temperature on a cool day
Original gases disappeared. Atmosphere is mostly due to volcanoes and plants!
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Ozone Hole over Antarctica
Led to banning of Chlorofluorocarbons worldwide
Had been used in refrigerators/air conditioners, aerosol cans, and as a cleaning solvent
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Intergovernmental Panel on Climate Change (IPCC – UN Agency) says
Translating terminology into probabilities
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Intergovernmental Panel on Climate Change (IPCC – UN Agency) says
What does this mean?
The consensus of the IPCC is that there is a 90% probability that human activity contributed signifcantly to the 1 degree F increase in global temperature over the past 50 years.
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About 2 degrees F since 1850
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Temperature for last 14,000 years
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Burning carbon-containing fossil fuels produces carbon dioxide.
(Combustion)C + O2 CO2
Global Warming Basics
Burning Fossil Fuels is the Primary CauseBurning Fossil Fuels is the Primary Cause
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Global Warming BasicsG
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Humans have increased carbon dioxide (CO2) in the
atmosphere by more than
35% since the Industrial Revolution. (National Oceanic and
Atmospheric Administration 2006)
The most carbon dioxide in 650,000 years. (IPCC 2007)
Jan 2011 – 390.67 PPMJan 2012 – 392.76 PPM
80% of all greenhouse gas emissions (National Library of Medicine)
(CO2)
10,000 BC 2009
391ppm
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CO2 in Atmosphere and Temperature
Note variation vs. local change
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CO2 in Atmosphere and Temperature
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Temperature Predictions
.
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CO2 in Atmosphere and Temperature
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CO2 in Atmosphere
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Temperature Predictions
.
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Alaska is Ground ZeroAlaska is Ground Zero
Chapman and Walsh, 2004
In past 50 years,
Alaska: Temperatures haveincreased
• 4oF overall(National Assessment Synthesis Team)
Worldwide:Temperatures haveincreased
• Slightly more than 1oF
(IPCC 2007)
Surface Air Temperature Trends 1942-2003
Global Warming BasicsG
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Chapman and Walsh, 2004
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Snow and sea ice reflect 85-90% of sun’s energy.
Ocean surface and dark soil reflect only
10-20%.
The Albedo Effect
“White shirt versus Black shirt”
Why has Alaska warmed the most?Why has Alaska warmed the most?
Increased melting of snow
and sea ice
Increased melting of snow
and sea ice
More of sun’s heat energy is
absorbed
More of sun’s heat energy is
absorbed
More dark earthand ocean surface
is exposed
More dark earthand ocean surface
is exposedLand or water warms faster
Land or water warms faster
Global Warming BasicsG
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(ACIA 2004)
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Source ACIA, 2004Jennifer Allen Animation
An area twice the size of Texas has melted away since 1979 (over 20%
decrease). (National Snow and
Ice Data Center 2005)
Ice 40% thinner. (Rothrock,D.A, et al. 1999)
Ice only 6 – 9 feet thick at North Pole (NOAA FAQ 2007).
Northwest passage opened Aug 21, 2007
Impacts in Alaska1. Melting
Melting Sea IceMelting Sea Ice
1978 1983 1988 1993 1998 2003
9
8
7
6
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-
-
-| | | | |
Arc
tic S
ea Ic
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km
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Source: NSIDC, 2005
ARCTIC SEA ICE AREA1979-2005
2005Glo
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Impacts in Alaska1. Melting
The rapid retreat of Alaska’s glaciers represents about 50% of the estimated mass loss by glaciers through 2004 worldwide. (ACIA 2004)
Loss of over 588 billion cubic yards between ’61 and ’98. (Climate Change 11/05)
Alaska’s glaciers are responsible for at least 9% of the global sea level rise in the past century. (ACIA 2004)
19411941
20042004
Glacier Bay (Riggs Glacier)
USGS photo
Bruce Molnia photo
Glacial RetreatGlacial Retreat
20032003
Mat
t Nol
an p
hoto
Aus
tin P
ost p
hoto
19581958
McCall Glacier
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• Polar bears• Walruses• Ice seals• Black guillemots• Kittiwakes• Salmon• Caribou
Impacts in Alaska3. Animals
Animals at RiskAnimals at Risk
Rising temperatures
Shrinking habitat
Food harder to get
Expanding diseases
Competition
Polar bearsWalrusesIce seals
Caribou
Black guillemotsKittiwakesSalmon
Arctic grayling
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Ocean AcidificationOcean Acidification
CO2 + H20 HCO3- + H+
Water becomes more acidic.
(ACID)
Remains in the atmosphere (greenhouse gas)
Dissolves in sea water
CO2
CO2
Over the last 200 years, about 50% of all CO2 produced on earth has been absorbed by the ocean.
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(Royal Society 6/05)
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Inundation
Sea level has increased 3.2 mm/year between 1993 and 2008 (IPCC 2007).
This is 10-20 times faster than during the last 3,000 years (ACIA 2004).
0.4-0.6 meters of sea level rise by 2100 if 3 times pre-industrial CO2 or 1% increase/year (Overpeck et al. 2006).
As Greenland and Antarctic ice sheets melt ...
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Ocean Nations Threatened
Maldives nation held cabinet meeting 20 feet under water.
Tuvalu nation considering exodus (highest elevation is 15 feet)
New Moore Island goes under in March 2010
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Inundation InundationInundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge)
Weiss and Overpeck, 2006
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Pho
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of 7
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.com
What We Can DoWhat We Can Do
1. Is it Achievable?
2. Action Is Essential at Every Level
• Individual• Corporate• Local• State• Federal• International
3. Critical Steps
R E D U C E C O 2 E M I S
S I O N S
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1954 2004 2054
14
7
1.9
Carbon Emissions(Billions of tons per year)
Current P
ath
At leastTRIPLING
CO2
Avoiddoubling
CO2
Flat Path
STABILIZATION TRIANGLE
What We Can DoIs it Achievable?Is it Achievable?
Pacala and Socolow, Science 2004Glo
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Inundation
Sea level has increased 3.2 mm/year between 1993 and 2008 (IPCC 2007).
This is 10-20 times faster than during the last 3,000 years (ACIA 2004).
0.4-0.6 meters of sea level rise by 2100 if 3 times pre-industrial CO2 or 1% increase/year (Overpeck et al. 2006).
As Greenland and Antarctic ice sheets melt ...
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Ocean Nations Threatened
Maldives nation held cabinet meeting 20 feet under water.
Tuvalu nation considering exodus (highest elevation is 15 feet)
New Moore Island goes under in March 2010
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Inundation InundationInundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge)
Weiss and Overpeck, 2006
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Pho
to c
ourt
esy
of 7
sum
mits
.com
What We Can DoWhat We Can Do
1. Is it Achievable?
2. Action Is Essential at Every Level
• Individual• Corporate• Local• State• Federal• International
3. Critical Steps
R E D U C E C O 2 E M I S
S I O N S
Glo
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1954 2004 2054
14
7
1.9
Carbon Emissions(Billions of tons per year)
Current P
ath
At leastTRIPLING
CO2
Avoiddoubling
CO2
Flat Path
STABILIZATION TRIANGLE
What We Can DoIs it Achievable?Is it Achievable?
Pacala and Socolow, Science 2004Glo
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What We Can Do
Wind PowerWind Power
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Measuring Your Carbon Footprint
Major Carbon Contributors:
Electric Consumption Gas/Heating Oil Consumption Car and Miles Driven Miles Flown Recreational Vehicle Use
Average Footprint is 30,000 pounds
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Making a Difference as an Individual
Conservation Measures:
Walk, bike, ride public transit, or carpool
Make sure your tires are fully inflated and your car tuned up Lower your water heater and
home thermostats Don't preheat your oven Only run your dishwasher with
full loads paint your roof white Buy locally produced food Unplug appliances not in use Turn off lights when leaving a room Use recycled paper Reuse or recycle as much as you can Cut down on consumerism
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Conservation: Three Examples
Unplug Appliances Vampires! 43 billion kWH lost/year in
US Est: 1,000 lbs/year/person
Pump Up Tires 4 million gallon of gas
wasted daily in US Extends life of tires by 25% Est: 1,000 lbs/year/person
Lower Thermostat 2 degrees Est: 2000 lbs/year/person
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Energy Efficiency: Two Examples
Compact Fluorescents Four to six times more
efficient Est: for each bulb
converted, save about 100 lbs/year
Bus/Walk/Bike Save money on fuel and
maintenance Est: 5,000 lbs/year
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Clicker Question:
What steps are you willing to take to reduce your carbon dioxide footprint?
A: Walk/bike/bus to work
B: Unplug appliances when not in use
C: Replace light bulbs with compact fluorescents
D: Wash clothes in cold or warm water
E: Buy a Prius
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Clicker Question:
A leading cause of Global Warming is:
A: Increased soot (smog) in the atmosphere.
B: Increased carbon dioxide in the atmosphere.
C: The Earth is getting closer to the sun.
D: The luminosity of the sun is steadily increasing.
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Clicker Question:
The Greenhouse effect would not occur if:
A: The Earth had no atmosphere.
B: The amount of carbon dioxide doubled.
C: We got rid of all the forests.
D: The Earth didn’t have an ocean.
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Jovians, Moons, and Rings
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Jupiter's Internal Structure
Can't observe directly. No seismic information. Must rely on physical reasoning and connection to observable phenomena.
(acts like a liquid metal, conducts electricity) Core thought to be molten or partially molten rock,
maybe 25 g/cm3, and of mass about 10-15 MEarth
.
Other Jovians similar. Interior temperatures, pressures and densities less extreme.
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Jupiter has a strong magnetic field
detection of the magnetic belts aroundJupiter
synchrotron emissionfrom energetic particlesin magnetic fields
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Jupiter has a strong magnetic field
detection of aurorae
Impact of high-energy Particles at the poles.
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Rapid rotation causes Jupiter and Saturn to bulge:
Gravity
without rotation with rotation
Gravity
Jupiter and Saturn rotate every ~10 hours. Radius at equator several % larger due to bulge.
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Clicker Question:
The Great Red Spot is:
A: A large basin on Mars
B: A long-lived high-pressure storm in Jupiter’s atmosphere.
C: The colored polar cap of Jupiter
D: Clouds of dust swirling around Jupiter’s largest volcano
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Clicker Question:
Saturn is less massive than Jupiter but almost the same size. Why is this?
A: Saturn’s interior is hotter than that of Jupiter’s.
B: Saturn is composed of lighter material than Jupiter.
C: Saturn is rotating faster than Jupiter so the increased centrifugal force results in a larger size
D: Saturn’s smaller mass provides less gravitational force to compress it.
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Differential Rotation
Rotation period is shorter closer to the equator:
Jupiter
Saturn
Uranus
Near poles At equator
9h 56m
10h 40m
16h 30m
9h 50m
10h 14m
14h 12m
How do we know?
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Differential Rotation
Rotation period is shorter closer to the equator:
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Uranus' rotation axis is tilted by 98o
Why? Unknown. Perhaps an early, grazing collision with another large body.
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The Ice Giants - Uranus and Neptune
NeptuneUranus
15 to 17 times the mass of the Earth Slushy water and methane ice atmospheresRocky cores of ~1 Earth massOff axis magnetic fields
No large moons 1 large moon (Triton)Not much internal heating 3 times more internal power than solar
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Moons of Jovian Planets
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The Galilean Moons of Jupiter
Closest to Jupiter Furthest from Jupiter
(sizes to scale)
Radii range from 1570 km (Europa, slightly smaller than our Moon), to 2630 km (Ganymede - largest moon in Solar System).
Orbital periods range from 1.77 days (Io) to 16.7 days (Callisto).
The closer to Jupiter, the higher the moon density: from 3.5 g/cm3 (Io) to 1.8 g/cm3 (Callisto). Higher density indicates higher rock/ice fraction.
Io Europa Ganymede Callisto
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Io's Volcanism
More than 80 have been observed. Can last months or years.
Ejecta speeds up to 1000 m/s. Each volcano ejects about 10,000 tons/s
Rich in S, SO2. S can be orange, red, black depending on temperature.
Frozen SO2 snowflakes are white.
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Voyager 2 (1979) Galileo (1996)
Activity causes surface to slowly change over the years:
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Volcanic activity requires internal heat. Io is a small body. Should be cold and geologically dead by now. What is source of heat?
First, Io and Europa are in a "resonance orbit":
Day 0
Europa
Io
Day 1.77
Europa
Io
Day 3.55
Europa Io
The periodic pull on Io by Europa makes Io's orbit elliptical.
Jupiter
Jupiter
Jupiter
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Ioorbital speed slower
orbital speed faster
- Tidal bulge always points to Jupiter. So the angle of the bulge changes faster when Io is closer to Jupiter.
(exaggerated ellipse)
- But Io rotates on its axis at a constant rate.
- So bulge moves back and forth across surface => stresses => heat => volcanoes
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Europa may have Warm Ocean beneath Icy Surface
860 km
42 km
Icebergs or "ice rafts" suggest broken and reassembled chunks.
Dark deposits along cracks suggest eruptions of water with dust/rock mixed in (Europa’s density => 90%rock, 10% ice).
Fissures suggest large moving ice sheets.Hardly any impact craters.