Chapter 13: Earth

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Chapter 13 Earths Atmosphere and Climate

• Big Question
• Global Warming Is Happening What Part Do We Play?

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Is the Global Temperature Rising?

• Yes, and it is rising globally.
• Has the temperature risen steadily?

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What Causes Climate Change and What Is Making It
Get Warmer?

• Studies of ice cores show Earths surface
  temperature has varied over time.

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• The answer lies in the Earths energy balance
  between the amount of energy coming in from the
  sun and the amount of energy radiated out by the
  Earth.

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Albedo

• Albedo the percentage of light received by a
  surface that is reflected and scattered

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Variation in the Suns Energy May Be A Reason for
Climate Changes

• The suns energy seems to have varied over the
  ages.
• The Little Ice Age lasted from about 1450 to 1850.

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Milankovich Cycles Another Possible Explanation

• Some temperature cycles stem from Earths wobble
  in an elliptical orbit.

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Volcanoes Can Alter Climate

• Volcanic eruptions cool the climate in two ways
• - Atmospheric dust reflects sunlight back
  into
• space
• - Smaller dust particles provide water
  condensing
• surfaces, forming clouds

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Dust from Our Own Activities Also Cools the
Climate

• Aerosol pollution particles reduce amount of
  sunlight reaching Earth. Emissions have reduced
  global warming.

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Variations in Ocean Currents May Affect the
Climate

• Ocean currents and prevailing winds warm or cool
  our planet.
• The Gulf Stream a major ocean circulation
  affecting climate.

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El Niño A Climate Phenomenon Linked to Ocean
Currents
Source Available at http/envisat.esa.int/live/en
visat_live_09.htm.
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The Greenhouse Effect, and How It Warms Earths
Surface
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Greenhouse Gases Are Increasing

• We are part of the reason.
• Carbon dioxide has been increasing in the
  atmosphere for some time.

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Would It Really Be So SeriousIf Earth Warmed Up
a Bit?
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• Computer models are the major scientific tool in
  step one. Model results global warming will
  increase Earths surface temperature by 1.5 to
  4.5C from 1990 to 2100.

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The Effects of a Rising Sea Level

• Risen naturally since last ice age.
• Increases damage from major storms.

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Global Warming Affects on World Climate

• Glaciers are melting while Antarcticas central
  ice cap is growing.
• Change frequency and intensity of storms.
• Other climate changes include wetter winters,
  hotter and drier summers, and increased droughts.

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Agriculture

• Global warming may seriously affect worlds food
  supply.
• The best agricultural areas may no longer be in
  North America.
• Winter snowpacks will store less water.

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Lowering of Water Tables and Reservoirs

• Could cause serious water supply shortages.
• Water use in some regions is already
  unsustainable.

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Biological and Ecological Changes
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Endangered Species

• What will happen to species that can not migrate
  nor adapt?
• Case Study Kirtlands warbler an
  endangered-species success story

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• Kirtlands warblers require a very specific
  habitat. They nest only in young jack-pine
  woodlands. To save these birds, 38,000 acres were
  set aside in Michigan.

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Slowing the Temperature Rise

• Reduce production and release of greenhouse
  gases.
• Find ways to sequester (store) greenhouse gases.
• Actively cool the climate.

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Chapter 13 Earths Atmosphere and Climate

• Questions? E-mail your TA.