Internal Structure and Geological History

Internal structure of Mercury, Mars, and the Moon, compared to Earth

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.

Earth has a small greenhouse effect; it is in equilibrium with a comfortable (for us) surface temperature.

Atmospheric Evolution on Earth, Venus, and Mars

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.

The Habitable Zone or “The Goldilocks Problem”In the zone …

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!

Ozone Hole over Antarctica

Led to banning of Chlorofluorocarbons worldwide

Had been used in refrigerators/air conditioners, aerosol cans, and as a cleaning solvent

Intergovernmental Panel on Climate Change (IPCC – UN Agency) says

Translating terminology into probabilities

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.

About 2 degrees F since 1850

Temperature for last 14,000 years

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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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

CO2 in Atmosphere and Temperature

Note variation vs. local change

CO2 in Atmosphere and Temperature

Temperature Predictions

.

CO2 in Atmosphere and Temperature

CO2 in Atmosphere

Temperature Predictions

.

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

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Chapman and Walsh, 2004

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

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(ACIA 2004)

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

-

-

-

-| | | | |

Arc

tic S

ea Ic

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xten

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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

• 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

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)

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 ...

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

Inundation InundationInundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge)

Weiss and Overpeck, 2006

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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

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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 ...

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

Inundation InundationInundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge)

Weiss and Overpeck, 2006

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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

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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?

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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

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

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

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

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

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.

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.

Jovians, Moons, and Rings

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.

Jupiter has a strong magnetic field

detection of the magnetic belts aroundJupiter

synchrotron emissionfrom energetic particlesin magnetic fields

Jupiter has a strong magnetic field

detection of aurorae

Impact of high-energy Particles at the poles.

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.

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

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.

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?

Differential Rotation

Rotation period is shorter closer to the equator:

Uranus' rotation axis is tilted by 98o

Why? Unknown. Perhaps an early, grazing collision with another large body.

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

Moons of Jovian Planets

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

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.

Voyager 2 (1979) Galileo (1996)

Activity causes surface to slowly change over the years:

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

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

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.