Earth as Planet and Ice Melting Lecture Notes

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Transcript Earth as Planet and Ice Melting Lecture Notes

Chapter 10
Global Effects
Lecture #21
HNRT 228 Spring 2013
Energy and the Environment
Adapted from UNM and USGS
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Chapter 10+ Overview
•
•
•
•
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Earth as a planet
The polar regions and sea ice effects
The stratospheric ozone situation
Another look at greenhouse gasses
Climate change
Global warming
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iClicker Question
Which of the following layers of the
atmosphere is highest above the surface
of the Earth?
A Troposphere
B Stratosphere
C Thermosphere
D Mesosphere
E Ozone Layer
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iClicker Question
What is the primary ingredient of the
Earth's atmosphere?
A Nitrogen
B Oxygen
C Nitrogen and oxygen in equal parts
D Hydrogen
E Carbon dioxide
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iClicker Question
In what part of the atmosphere does
weather occur?
A Hydrosphere
B Stratosphere
C Ionosphere
D Troposphere
E All of the above
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iClicker Question
How rapidly a planet loses its atmosphere depends on
the planet's
•
I.
mass
•
II.
atmospheric composition
•
III.
temperature
•
IV.
rotation period
A
B
C
D
E
I & II
III & IV
I, II, & III
II, III, & IV
I, II, III, & IV
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iClicker Question
The presence of Earth’s magnetic field is a good
indication that
A there is a large amount of magnetic material
buried near the North Pole.
B there is a quantity of liquid metal swirling
around in the Earth's core.
C the Earth is composed largely of iron.
D the Earth is completely solid.
E there are condensed gasses in the core of the
Earth.
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The Earth
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General Features
Mass: MEarth = 6 x 1027 g
Radius: REarth = 6378 km
Density:  = 5.5 g/cm3
Age: 4.6 billion years
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Earth's Internal Structure
How do we know? Earthquakes. See later
Crust: thin. Much Si and Al
(lots of granite). Two-thirds
covered by oceans.
Mantle is mostly solid,
mostly basalt (Fe, Mg, Si).
Cracks in mantle allow
molten material to rise =>
volcanoes.
Core temperature is ~6000 K.
Metallic - mostly nickel and
iron. Outer core molten, inner
core solid.
Atmosphere very thin
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Earth's Atmosphere
78% Nitrogen
21% Oxygen
Original atmosphere changed over time.
Atmosphere today is largely due to
volcanoes and life (especially plant).
gas is ionized by
solar radiation
ozone is O3 , which
absorbs solar UV
efficiently, thus
heating
stratosphere
commercial jet
altitudes
room temperature
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Ionosphere
Particles in the upper reaches of the atmosphere are ionized by
the sun.
Radio signals below ~20 MHz can “bounce” off the ionosphere
allowing communication “over the horizon”
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Convection
Earth's surface heated by Sun. What would happen if it
couldn't get rid of the energy as fast as it gets in?
Convection also
occurs when you
boil water, or soup.
Think of Earth's
surface as a
boiling pot!
Convection causes both small-scale turbulence and large scale
circulation patterns. It also occurs within Earth, on other
planets, and in stars.
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The Greenhouse Effect
Main greenhouse
gases are H2O
and CO2 .
If no greenhouse
effect, surface
would be 40 oC
cooler!
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iClicker Question:
The dinosaurs were most likely wiped
out by:
A: disease
B: hunting to extinction by cavemen
C: a giant meteor impact
D: the close passage of another star
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iClicker 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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iClicker 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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Pollution
C + O2
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
(Combustion)
CO2
Burning carbon-containing fossil fuels
produces carbon dioxide.
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CO2: Most Significant Greenhouse Gas
Global Warming: The Greatest Threat © 2006 Deborah L. Williams

Humans have
increased
carbon dioxide
(CO2) in the
atmosphere by
more than 35%
since the
Industrial
Revolution.
CO2
CH4
(National Oceanic and
Atmospheric Administration
2006)

The most carbon
dioxide in
650,000 years.
(IPCC 2007)
Jennifer Allen
graphic
Source: ACIA
2004
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Temperature Measurements
“Warming of
the climate
system is
UNEQUIVOCAL”
(IPCC 2007)
Top 11
warmest years
on record have
all occurred in
the last 12
years.
(IPCC 2007)
2006 warmest
year on record in
continental US.
(NOAA 1/07)
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Alaska as Ground Zero for Warming
Surface Air Temperature Trends 1942-2003
In past 50 years,
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
Alaska:
Temperatures have
increased
• 4oF overall
(National Assessment Synthesis
Team)
Worldwide:
Temperatures have
increased
• Slightly more
than 1oF
(IPCC 2007)
Chapman and Walsh, 2004
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Why has Alaska warmed the most?
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
The Albedo Effect
 Snow and sea ice
reflect 85-90% of sun’s
energy.
Increased
melting of snow
and sea ice
 Ocean surface and dark
soil reflect only 10-20%.
Land or water
warms faster
More dark earth
and ocean surface
is exposed
(ACIA 2004)
More of sun’s
heat energy is
absorbed
“White shirt versus Black shirt”
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Impacts in Alaska
1. Melting
Melting Sea Ice

An area twice the size
of Texas has melted
away since 1979 (over
20% decrease). (National

Ice 40% thinner.
(Rothrock,D.A, et al. 1999)

Source ACIA, 2004
Jennifer Allen Animation
Arctic Sea Ice Extent (millions of sq. km.)
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
Snow and Ice Data Center 2005)
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-
8
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7
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6
-
(NOAA FAQ 2007).
ARCTIC SEA ICE AREA
1979-2005
Source: NSIDC, 2005
1978
Ice only 6 – 9 feet
thick at North Pole
|
1983
1988
|
1993
|
1998
|
2003

|
2005
Northwest passage
opened Aug 21, 2007
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Impacts in Alaska
Melting Sea Ice
1. Melting
Arctic Ocean could be ice free in summer by 2040
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
(U.S National Center for Atmospheric Research 2006).
“Our research indicates that society can still
minimize the impacts on Arctic ice.”
Dr. Marika Holland, National Center for Atmospheric Research
2000
2040
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Impact World-wide
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
Impact on Ski Industry
1. Melting
•
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In the US skiing is a $5B industry
2006 saw a 78% decline in skiers visiting the pacific northwest US
Ski Seasons have shortened by 1 day/year for the last 20 years
Many European ski resorts below 1800 m (6000 ft) will close
50 to 90% of Alpine glaciers will be gone by 2100
Some resort to snowmaking
• Expensive
• Requires lots of water
• Requires lots of energy
• In New Mexico, many ski areas
can’t open until after Xmas
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Impacts in Alaska
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
The rapid retreat of
Alaska’s glaciers
represents about 50%
of the estimated mass
loss by glaciers
through 2004
worldwide. (ACIA 2004)
McCall Glacier
Glacier Bay (Riggs Glacier)
1941
1958
Austin Post photo
Glacial Retreat
1. Melting
USGS photo
Loss of over 588 billion
cubic yards between
’61 and ’98. (Climate Change

Alaska’s glaciers are
responsible for at least
9% of the global sea
level rise in the past
century. (ACIA 2004)
2004
2003
att Nolan photo
11/05)
Bruce Molnia photo 26
Melting of the Greenland Ice Sheet
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According to NASA scientists, the Greenland ice sheet
is melting faster than it is being replaced, contributing
to sea level rise
The loss of ice from Greenland doubled between 1996
and 2005
From 1996 to 2000, the largest acceleration and mass
loss came from southeast Greenland
From 2000 to 2005, the trend extended to include
central east and west Greenland
It is estimated that 69 per cent of the ice-mass loss in
recent years came from eastern Greenland
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Greenland ice is declining faster than expected
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Between 2003 and 2005 the low coastal areas of Greenland lost
155 gigatons of ice per year due to excess melting while the high
elevation interior gained 54 gigatons annually from excess
snowfall
Between 2004 and 2006, the rate of melting accelerated, with
the massive ice sheet melting two and one-half times faster
than the previous two-year period
Greenland lost roughly 164 cubic miles of ice from April 2004 to
April 2006—more than the volume of the North American Great
Lake Erie
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Greenland Ice Sheet
Dramatic ice
mass losses
concentrated
in the lowelevation
coastal
regions, with
nearly half of
the loss
coming from
southeast
Greenland
NASA Earth Observatory
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Greenland Ice Sheet
Greenland is
now losing 20
percent more
mass than it
receives from
new snowfall
each year.
NASA Earth Observatory
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Greenland Ice Sheet
University of Colorado, CIRES
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Melting of ice in Greenland
2001-2003:
A significant
increase in
the melting
area has been
observed
along the edge
of the ice cap
in Greenland.
NASA Earth Observatory
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Retreat of Ice and Snow in Greenland
Ice loses in Greenland range
from 5 to 25 centimeters of
water equivalent per year
NASA Earth Observatory
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Calving of Helheim Glacier, Greenland
The glacier’s peak rate of
flow has increased from 8
km/yr in 2000 to 11
km/yr in 2005
Helheim glacier, located in
southeast Greenland, is
now one of the fastest
moving glaciers in the world
1986-2006: These images
show the retreat of
Helheim glacier’s calving
front
 This May 2005 picture
of Helheim Glacier,
demonstrates high calving
activity associated with
faster glacial flow
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Dramatic changes in Arctic Sea Ice
Imagine
an icefree
Arctic
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Evidence of extensive snowmelts in
West Antarctica
•
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January 2005:
Areas of extensive
snowmelt (shown in
yellow and red) have
been discovered by
a team of NASA
and university
scientists in
response to warmer
temperatures in
west Antarctica .
The combined area
affected is as big as
California.
NASA Jet Propulsion Laboratory
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Breakup of Larsen ice shelf
(Antarctic Peninsula)
220 metres thick
Larsen B shelf
existed for at
least 400 years
prior to breakup
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Disintegration of the Larsen B Ice Shelf, Antarctic Peninsula
The ice shelf
disintegrated
suddenly in
March 2002
due to warm
summer
temperatures
NASA Earth Observatory
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Breakup of Antarctica’s Ross Ice Shelf
•
•
An iceberg (B-15J)
of size of a small
United States state
cracked off the
Antarctica’s Ross
Ice Shelf in March
2000
On February 1,
2007, three new
icebergs were
formed due to the
break up of the
original iceberg
NASA Earth Observatory
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Breaking Off Filchner Ice Shelf Antarctica
Filchner
Ice Shelf
is the
largest ice
shelf on
the planet
In 1986 the
front edge of
Ice Shelf
broke off into
three enormous
icebergs
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Calving of Ninnis Glacier Antarctica
22 January 2000:
The Ninnis
Glacier Tongue
soon after the
initial calving
5 February
2002: Iceberg
split into two
sections and
started moving
away from
Ninnis Glacier
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Cracks on Drygalski Ice Tongue Antarctica
The ice tongue
was discovered
in 1902
21 February
2005: Drygalski
calved an iceberg
Image shows
cracks formed
by time and
ocean currents
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Shrinking Lake Chad shared by
Nigeria, Niger, Chad and Cameroon
Persistent drought has
shrunk the lake to about
a tenth of its former
size
• 1972: Larger lake
surface area is visible in
this image
• 2001: Due to regionally
drying climate and human
demand for fresh water,
Lake Chad is fraction of
what is once was
• 2004: In many places, the
green of wetlands is being
replaced by drifting sand
dunes (tan ripples mixed
with green)
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Shrinking Breidamerkurjökull Glacier Iceland
• 1973-2000:
Images show
glacier has
receded and the
glacial lake at its
tip has enlarged
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Ayles Ice Shelf, Ellesmere Island, Canada
• 1986: Images show
Degradation of forest
area
• 2001: Between
1984 and 1999, 38
per cent of forests
were degraded
Ayles Ice Shelf on
Ellesmere Island, broke free
on August 13, 2005 and
drifted out to the sea
NASA Earth Observatory
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Disappearing Icecap of
Mt. Kilimanjaro, Tanzania
Africa’s highest
mountain with a forest
belt having rich
diversity of ecosystems
• 1976: Glaciers covered
most of the summit
• 2000: The glaciers had
receded alarmingly
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Retreat of Gangotri Glacier, India
•
•
Gangotri
glacier has
retreated
more than 850
meters, in the
last 25 years
It has
retreated
more than 76
meters from
1996 to 1999
NASA Earth Observatory
47
Glacial Lakes and Glacial Lake Outburst Floods
Glacial Lakes in the Bhutan-Himalaya Region
•
•
•
Jeffrey Kargel, USGS/NASA JPL/AGU
Glacial lakes are formed due
to the melting of ice and
snow from glaciers
Due to the faster rate of
melting from the glaciers,
possibly due to global
warming, water is
accumulating at an increasing
rate in these lakes
Sudden outburst results in
Glacial Lake Outburst Flood
(GLOF) downstream causing
destruction of life and
property
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Retreat of Upsala Glacier, Argentina
January 2004
position
The Upsala glacier has retreated
more than 4 kilometers since late
1960’s to mid 1990’s and
continues to retreat
NASA Earth Observatory
49
Retreat of San Quintin Glacier, Chile
The San Quintin Glacier
appears to be losing mass and
retreating
NASA Earth Observatory
50
Impacts in Alaska
Animals at Risk
3. Animals
Polar bears
Walruses
Ice seals
Black guillemots
Kittiwakes
Salmon
Caribou
Arctic grayling
 Rising temperatures
 Shrinking habitat
 Food harder to get
 Expanding diseases
 Competition
51
Inundation
 Sea level has increased 3.1
mm/year between 1993 and
2003 (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 preindustrial CO2 or 1%
increase/year
(Overpeck et al. 2006).
52
Inundation
Inundation from Four Meter Sea Level Rise (or, 1m rise
Weiss and Overpeck, 2006
+ 3m storm surge)
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What We Can Do
R E D U C E CO 2
EMISSIONS
1. Is it Achievable?
2. Action Is Possible at Every
•
•
•
•
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•
Individual
Corporate
Local
State
Federal
International
3. Some Steps
Photo courtesy of 7summits.com
Global Warming: The Greatest Threat © 2006 Deborah L. Williams
Level
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Global Warming: The Greatest Threat © 2006 Deborah L. Williams
What We Can Do
Wind Power
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Measuring Your Carbon Footprint
Major Carbon Contributors:


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
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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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Conservation: Three Examples
What We Can Do
Unplug Appliances
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Vampires!
43 billion kWH lost/year in US
Est: 1,000 lbs/year/person
Pump Up Tires
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4 million gallon of gas wasted
daily in US
Extends life of tires by 25%
Est: 1,000 lbs/year/person
Lower Thermostat
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
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
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
Save money on fuel and
maintenance
Est: 5,000 lbs/year
58
Earthquakes
They are vibrations in the solid Earth, or seismic waves.
Two kinds go through Earth, P-waves ("primary") and S-waves ("secondary"):
59
How do they measure where Earthquakes are centered?
seismic
stations
*
*
*
60
Like all waves, seismic waves bend when they encounter
changes in density. If density change is gradual, wave path is
curved.
S-waves are unable to travel in liquid.
Thus, measurement of seismic wave gives info on density of
Earth's interior and which layers are solid/molten.
Zone with no S waves:
must be a liquid core
that stops them
But faint P waves
seen in shadow zone,
refracting off dense
inner core
No P waves too:
they must bend sharp
at core boundary
Curved paths of
P and S waves:
density must slowly
increase with depth
61
Earth's Interior Structure
Average
density
5.5 g/cm3
Crust
Mantle
Core
3 g/cm3
5 g/cm3
11 g/cm3
Density increases with depth => "differentiation"
Earth must have been molten once, allowing denser
material to sink, as it started to cool and solidify.
62
Earthquakes and volcanoes are related, and also don't occur at
random places. They outline plates.
Plates moving at a few cm/year. "Continental drift" or "plate
tectonics"
63
When plates meet...
1) Head-on collision
(Himalayas)
side view
2) "Subduction zone"
(one slides under the other)
(Andes)
3) "Rift zone"
(two plates moving apart)
(Mid-Atlantic Ridge, Rio Grande)
4) They may just slide past each
other
(San Andreas Fault)
=> mountain ranges, trenches, earthquakes,
volcanoes
top view
64
iClicker Question:
Sunlight absorbed by the Earth’s
surface is reemitted in the form of?
A: radio waves
B: infrared radiation
C: visible radiation
D: ultraviolet radiation
E: X-ray radiation
65
iClicker 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
66
The Mid-Atlantic Ridge
is a rift zone.
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What causes the drift?
Convection! Mantle slightly fluid and can support convection.
Plates ride on top of convective cells. Lava flows through cell
boundaries. Earth loses internal heat this way.
Cycles take ~108 years.
Plates form lithosphere (crust and solid upper mantle).
Partially melted, circulating part of mantle is
asthenosphere.
68
Pangaea: 200 million years ago, all the continents
were close together.
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