Global Climate Cycles, Global Warming and Anthropogenic Greenhouse Effect

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Global Climate Cycles,Global Warmingand
Anthropogenic Greenhouse Effect
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Important considerations regarding global
warming and the anthropogenic greenhouse effect

• Cyclical Processes The earths environmental
  conditions have been evolving through geologic
  time. They tend to be cyclical over both long and
  short periods of time and have changed character
  greatly and abruptly.
• Chaos is an operating factor
• Positive Feedback vs Negative Feedback

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Brief History of Earth

• 4.5 b.y. ago earth formed from a cloud of dust
  and gas that circled proto-sun as a disc.
• Luminosity of sun was about 30 less than present
  in early history, yet earth was as warm then as
  now.
• Atmosphere had high content of CO2

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BBlack Dwarf
WWhite Dwarf
RRed Giant
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• There have been multiple periods of major
  continental glaciation.

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Continental Glaciation

• Approx. Time  of Glaciation Duration
• 2300 m.y. 200 m.y.
• 900 m.y. 50 m.y.
• 750 m.y. 50 m.y.
• 600 m.y 20 m.y.
• 450 m.y. 25 m.y.
• 300 m.y. 50 m.y.
• now about 10 m.y.so far

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• Continental Glaciation in North America and
  Europe  began about 1.6 m.y. ago (Pleistocene or
  ice ages).
• Glacial and interglacial periods cycle with a
  period of about 100,000 years.
• Interglacial periods are about 10,000 years in
  duration

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• First modern humans appeared about 200,000 years
  ago.
• Peak of last glaciation occurred about 20,000
  years ago.
• Sea level was 400 feet lower
• Long Island was not an Island then

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• Interglacial period began about 10,000 years ago.
  
• We are presently in an interglacial period.
• Agriculture started about 10,000 years ago.

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• Past is key to the future

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What will Long Island or the earth be like in

• 12 hours?
• 6 months?
• 100 years?
• 50,000 years?
• 2 b.y.?
• 5 b.y.?
• 7 b.y.?

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What Controls Earths Surface Temperature?

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10,000o F
60o F
0o F if no Greenhouse Effect
www.ultranet.com/jkimball/BiologyPages/
C/CarbonCycle.html
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Real-time measurements and historical records of
climate (back to 1800s some earlier)
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ToC
SGlobal Surface temperature
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GGlobal Surface TemperatureScientific American,
March 2005 p. 35
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CClimate Northern Hemisphere Moberg et al, 2005
Nature v 433, p. 613-617
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Record from position of glaciers
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Rhone Glacier (Present)
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Rhone Glacier (Present)
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Lithograph from 1850s
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EEurope during Little Ice Age
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Climate Northern Hemisphere Moberg et al, 2005
Nature v 433, p. 613-617
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VViking settlements during Medieval Warm Period
http//emuseum.mnsu.edu/prehistory/vikings/vikhome
.html
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20,000-40,000 year cycles
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100,000 year cycles
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GGreenhouse Gases
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Anthropogenic Greenhouse Gases

• Carbon Dioxide 60
• Burning of Fossil Fuels
• Deforestation
• Methane 15
• Coal Mines
• Termites
• Wetlands (beavers)
• Rice Patties
• Cattle
• Subpolar Soil and Wetlands
• Methane hydrate

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Methane Hydrate

• Immense Carbon reservoir
• Twice as large as all known fossil fuels
• Methane is 10 times more effective a greenhouse
  gas as carbon dioxide
• Occurs on sea floor at depths greater than about
  2,000 feet
• In polar sediments

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Global Carbon Budget
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Methane Hydrate
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Locations where methane hydratehas been
discovered
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• Mean global temperature has increased since
  mid-1800s
• Has CO2 ?
• Can we see correlations earlier? Glacier Ice.

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Projected Changes in Global Climate (Short-term)
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RRuddiman, 2005, Sci Am. March
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Ruddiman, 2005, Sci Am. March
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Ruddiman, 2005, Sci Am. March
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Ruddiman, 2005, Sci Am. March
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Ruddiman, 2005, Sci Am. March
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Consequences of Greenhouse Warming

• Increase in warming
• least in tropics
• greatest toward poles.

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Consequences of Greenhouse Warming

• Wandering weather patterns
• Increased precipitation
• Less rain in summer in U.S. midwest
• Intensity and numbers of storms will increase
• Ocean currents may be modified

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Consequences of Greenhouse Warming

• Expansion of Oceans on heating
• Melting of glaciers
• Sea level rise of 1 to 3 feet by 2100
• More severe storms
• Result will be coastal flooding

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Consequences of Greenhouse Warming

• Natural Habitats will be destroyed
• Forests dying
• Wild animals unable to migrate
  development isolation
• Areas with tropical diseases expand

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• Agriculture may be helped or hurt depending on
  area and ability of farmers to react fast enough
• Water for irrigation and human use may be
  inadequate for populations in drier areas

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General Strategies

• Waiting strategy
• Compromise
• increased energy conservation
• more reliance on renewable energy
• reduce deforestation

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The End