GLOBAL WARMING
© 2007 Paul Billiet ODWS
Sunlight energy
in the
atmosphere
© Windows to the Universe
The layers of
the atmosphere
The troposphere is the part of the
atmosphere in the biosphere
The stratosphere contains the
ozone layer
The stratosphere is also a zone of
warm air that keeps a lid on the
troposphere. It does not mix with
the upper atmosphere
© Text 2007 Paul Billiet ODWS
© Windows to the Universe
The Greenhouse Effect
© Oceanworld 2005 Robert R Stewart
The Greenhouse Effect
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The molecules of some gases in the
atmosphere absorb heat energy and retain it
This can be a good thing
Without an atmosphere the Earth would have
same temperature as the moon
Moon mean surface temperature -46°C
Moon temperature range: -233 to +123°C
© 2007 Paul Billiet ODWS
The Greenhouse Gases
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H2O vapour
CO2
CH4
NOx
CFC
© Oceanworld 2005 Robert R Stewart
© Text 2007 Paul Billiet ODWS
Infrared
Absorption
Spectra
© Oceanworld 2005 Robert R Stewart
The Greenhouse Gases
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Water vapour in the atmosphere is stable
The atmosphere is saturated
CO2 levels are currently rising
They have varied in the past
Methane levels are increasing:
as more cattle are farmed, as more paddy
fields are planted, as permafrost melts
NOx levels increase due to increased
circulation of motor vehicles
© 2007 Paul Billiet ODWS
Mauna Loa Observatory
© Mauna Loa Observatory Site
© Earth
System Research Laboratory
© Earth System Research Laboratory
Carbon dioxide a greenhouse gas
© Mauna Loa Observatory Site
South Pole Data
Samoa data
© Australian Antarctic Division
© New Scientist : Environment
Levels during the last ice age
© Dennis Hartmann: Universoty of Washington: Department of Atmospheric Sciences
Out of the ice age
Since the Industrial Revolution
Concentration of Carbon Dioxide from trapped air measurements for the DE08 ice core near the summit
of Law Dome, Antarctica. (Data measured by CSIRO Division of Atmospheric Research from ice cores supplied by
Australian Antarctic Division)
The oceanic conveyor belt
The melting
Arctic ice
The length of the melt season
inferred from surface
temperature weekly data has
been increasing by 9, 12, 12,
and 17 days per decade in sea
ice covered areas
© NASA
Is it really getting warmer
1979
© NASA
2003
The consequences
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Sea level rise
Flooding coastal areas
Reduced agricultural land
Displacement of populations
Climate change
Displacement of ecosystems
Change in range of insect vectors of
pathogens
Reduced biodiversity
© 2007 Paul Billiet ODWS
The consequences
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Increased rates of photosynthesis
Increased agricultural production at high
latitudes
BUT faster growth means:
less protein in cereals
trees taller and more exposed to storm
damage
© 2007 Paul Billiet ODWS
Knock-on effects
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Increased temperature melts the permafrost
Frozen plant remains decompose
More methane released
Similarly soils will lose organic carbon (humus) more
rapidly in a warmer climate
Ice caps melt more sea exposed
Snow reflects light (high albedo)
Water absorbs light, increases warming
More CO2 dissolving in water lowers pH
Currently this is buffered and remains stable
Eventually pH will drop sea life will die CO2
produced as organisms decompose
© 2007 Paul Billiet ODWS
What can be done?
Reduce carbon emissions
 Improve mass transport systems (public transport)
 Design more efficient motors
 Design alternative power sources
 Hydrogen powered motors
BUT problems of fuel reservoir, delivery, fabrication
 Renewable energy (wind, tidal, hydro, geothermal,
biomass)
BUT growing crops for biofuel reduces farmland
available for food
Hydroelectric dams disrupt river ecosystems
 Nuclear power
BUT problems of nuclear waste treatment/storage
© 2007 Paul Billiet ODWS
What can be done?
Increase natural CO2 sequestering
 Reduce deforestation
 Increase reforestation
© 2007 Paul Billiet ODWS
What can be done?
Artificial CO2 sequestering
 Filter CO2 sources using hydroxide scrubbers
 Injection of CO2 into deep ocean layers
Forms CO2 reservoirs
Impact on sea life unknown
 Injecting CO2 into disused oil wells
 Mineral deposition as carbonates
© 2007 Paul Billiet ODWS
The bottom line
Two factors will ultimately govern what happens:
1. Human population growth
More people means greater demand for nonrenewable resources
2. The ecological footprint of each individual
human
Higher standards of living usually means higher
consumption of fossil fuels
The planet will look after itself in the end
There are plenty of examples where human
communities have disappeared because they
outstripped the environmental resources
© 2007 Paul Billiet ODWS
The planet will look after itself in the end
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Easter Island (Rapanui) in the
Pacific
Settled between AD900 and
1200
Community in severe decline
AD 1700
Cause: excessive
deforestation
The Moai statues, Easter Island © Martin Gray, World Mysteries
© Text 2007 Paul Billiet ODWS
The planet will look after itself in the end
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Chaco Canyon, New
Mexico
Anasazi culture
AD 850 – 1250
Cause: Deforestation
combined with a
decline in rainfall
© New Mexico Tourism Department
© Text 2007 Paul Billiet ODWS
The planet will look after itself in the end
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Mesopotamia
Sumerian civilization
3100 – 1200 BC
Increased salt levels in
soil due to irrigation
systems & arid
environment
Reduced food yield
© Text 2007 Paul Billiet ODWS
© Asociación Cultural Nueva Acrópolis en Barcelona
The planet will look after itself in the end
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Greenland
Viking colony
AD982 – 1350
Cause: Deforestation,
soil degradation &
cooling of the climate
© Emporia State University
© Text 2007 Paul Billiet ODWS
Who’s next?
forumpolitics.com/pics/earth-photo.jpg
© NASA