Dynamics of Climate Change

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Dynamics of Climate Change
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Energy Transfer in the Climate System

• Earths climate is a complex system.
• A system is a group of independent parts that
  work together to form a single, functioning
  whole.
• An open system is a system in which energy and
  matter cross the systems boundary. (your body)
• A closed system allows energy but not matter to
  cross the boundary of the system. (The Earths
  climate system)
• As a closed system, Earth must constantly cycle
  the matter and energy within its boundary.

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• Interactions among different forms of matter and
  energy in Earths climate system create feedback
  loops.
• A Feedback loop is a process in which part of a
  systems output is returned to the input.
• In the Earths climate system, many feedback
  loops affect the conditions of the atmosphere,
  ocean and land.

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• A positive feedback loop acts to increase the
  effects of the interacting parts.
• Example effect of melting ice, decreases albedo
  (reflected light of surface), which increases
  warming, which increases the amount of melting
  ice, and so on.
• The small initial change in climate can lead to
  larger and larger changes.

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• Negative feedback loops decreases the interacting
  parts and help maintain the systems equilibrium.
• Checks and balances to prevent, slow or reverse
  change in a system.
• Example global warming increases rate of
  evaporation, increased water in atmosphere
  creates clouds, clouds create more albedo, which
  produces a cooling effect.

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Types of Energy Transfer

• Radiation transfer of energy as electromagnetic
  radiation.
• E.G. Sun to Earth, heat from fire, etc.
• Conduction transfer of energy between 2 objects
  in direct contact. Moves from an area of high
  heat to lower heat.
• E.G. hot plate on stove to frying pan to egg.
• Convection transfer of thermal energy by highly
  energized molecules.
• E.G. lava lamp

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Energy Transfer in Atmosphere

• Land and water gain thermal energy by absorbing
  the Suns short-wave radiation.
• As Earth warms, it emits long-wave radiation to
  the atmosphere, which heats the air and
  contributes to greenhouse effect.
• Conduction heats the air through collisions
  between molecules in the ground and in the air.
• Convection moves warm air from close to the
  ground upward and cool air from higher in the
  atmosphere downward.

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Convection, Conduction and Radiation transfer
heat in Earths Atmosphere
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Energy Transfer in the Oceans

• Uneven heating on Earth creates winds.
• Winds create currents of water that redistribute
  thermal energy at the ocean surface.
• Deeper, colder currents also move slowly along
  the ocean floor
• Like air masses, large masses of water can move
  vertically and horizontally.
• Cold water dense and sinks, pushing warm water
  out of the way
• Salt water dense and sinks.

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• Temperature, salinity, density of water create
  continuous, twisting ocean current that mixes
  ocean waters.
• Sometimes called the Great Conveyor Belt
• This pattern is known as thermohaline
  circulation.
• Creates a global system of thermal energy
  distribution

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Global Warming and Thermohaline Circulation

• Scientists are worried that global warming will
  affect the current pattern of circulation.
• Higher temps ? increased ice melting ?increases
  fresh water ?decreases salt content in northern
  water
• Higher temps ? increased evaporation ?increased
  salt levels in tropics
• Changes in ocean circulation patterns could have
  a negative effect on living things (manta ray) in
  the ocean by changing patterns of upwelling.
• Upwelling brings nutrients from sea floor to
  surface currents.

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Energy Transfer

• The importance of winds and ocean currents to
  global climate is seen best when there is a
  disruption to the system.
• Every few years in the tropics, there are events
  called El Nino and La Nina.

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El Nino

• Winds blowing west weaken and might reverse
• Warm waters in the western Pacific move eastward,
  preventing cold water from upwelling
• Can trigger changes in precipitation and
  temperature across North America.
• Heavy rains in California can lead to landslides

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La Nina

• Stronger than normal winds push warm Pacific
  waters farther west, towards Asia.
• Cold, deep-sea waters well up strongly in the
  Eastern Pacific
• Colder temperatures to northwestern North
  America.
• Moisture pushed away from N.America, parched
  lands.

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Earths Energy Budget

• Nearly a third of solar energy reaching Earth is
  reflected back.
• The 70 that is absorbed warms the ground, water,
  and air.
• The energy budget is a description of the total
  energy exchange within a system how much energy
  enters from the Sun and how much leaves the Earth
  system.

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Percentage of Absorbed and Reflected Energy
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Greenhouse Gases

• The concentration of carbon dioxide in Earths
  atmosphere increased from 315 parts per million
  (ppm) to 370ppm.
• 99 of the atmosphere is made up of nitrogen gas
  and oxygen gas.
• Neither absorbs infrared radiation or contributes
  to greenhouse gases.
• Carbon dioxide and water are the 2 most abundant
  greenhouse gases in our atmosphere.

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Water Vapour?

• Responsible for 65-85 of greenhouse effect
• Water is not added or removed to the atmosphere
  in significant amounts by humans.
• Temperature does control the amount of water in
  the atmosphere.
• Higher temperature more evaporation

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CO2 Sources and Sinks

• A sink is a process that removes greenhouse gases
  from the atmosphere.
• Plants are sinks
• Burning of fossil fuels and animal respiration
  are the major sources
• Phytoplankton (microorganisms) can absorb a lot
  of carbon dioxide as well.

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Methane greenhouse gas

• Produced in wetlands (bogs and swamps), rice
  paddies, termites and cattle naturally.
• Landfills, processing coal and natural gas and
  manure also emit methane.
• Suggestions? Make cows wear backpacks to capture
  the methane and use it as a fuel, feed cows
  clover and alfalfa to reduce methane, stop eating
  beef.

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Methane backpack!
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Ozone

• Ozone (O3) occurs naturally in the atmosphere and
  blocks UV radiation from the Sun.
• Since 1970, there has been a slow decline in the
  total ozone and a hole appeared over Antarctic.
• Not actually a hole, just an area where the ozone
  is thinning more than other areas around it.
• Cause human-made gases that contain chlorine

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Ground-Level Ozone

• Smog-forming pollutant
• Produced when sunlight reacts with chemicals and
  vehicle exhaust (hydrocarbons and nitrogen
  oxides)
• Can contribute to global warming.

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Halocarbons

• Formed when carbon is mixed with a halogen
  (iodine, fluorine, chlorine)
• Human-made
• Chlorofluorocarbons (CFCs) are best known in
  solvents, cleaners and coolants in fridges and
  air conditioners.
• Absorb infrared radiation so they are greenhouse
  gases and also break apart ozone molecules
• Remain in atmosphere for so long and continue to
  do damage
• Banned in 1987.