Volcanoes and Igneous Activity Earth Chapter 4

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Chapter 21.3 Verbal Notes
Climate Changes
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Climate Changes
Natural Processes That Change Climates
? Volcanic Eruptions
The presence of volcanic ash, dust, and
sulfur-based aerosols ejected into the air
increases the amount of solar radiation that is
reflected back into space.
Eruption of Mount Pinatubo

• The lack of solar radiation received causes
  Earths lower atmosphere to cool, which can cause
  short-term changes in the Earths surface
  temperature and climate.

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Climate Changes
Natural Processes That Change Climates
? Ocean Circulation

• Changes in ocean circulation also can result
  in short-term climate fluctuations.
• El Niño and La Niña both cause changes in ocean
  currents and circulation that can drastically
  affect the local weather and overall climate.

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Climate Changes
Effects of El Niño

• During El Niño some areas that are normally dry
  and arid receive large amounts of rain and some
  regions that receive heavy precipitation
  experience dry periods, all caused by changing
  ocean currents which affect the local weather and
  overall climate.

In 1998, bad weather conditions and flooding in
Alabama were attributed to El Niño
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Climate Changes
Natural Processes That Change Climates
? Solar Activity

• When the sun is most active, it contains dark
  blemishes called sunspots. The formation of
  sunspots appears to correspond with warm periods
  in Europe and North America.
• The variations in solar output may cause
  short-term climatic change, but no evidence for
  long-term climatic variations due to solar
  activity exist.

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Climate Changes
Natural Processes That Change Climates
? Earth Motions

• There are many motions by the Earth and on the
  Earths surface that are thought to cause changes
  in the Earths climate. Most of these are
  long-term climate changes and they include
• Geographic changes in the Earths land and water
  bodies.
• Tectonic plate movement causing changes in the
  position of the landmasses.
• Changes in the shape of Earths orbit.
• The Earths orbit varies slightly, sometimes it
  is more elliptical and sometimes it is less
  elliptical over a 100,000 year period.
• Changes in the tilt of Earth on its axis.
• Like its orbit, the tilt of the Earth changes
  2 over a 41,000 year
• period.

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Climate Changes
Human Impact on Climate Changes
? The Greenhouse Effect

• The greenhouse effect is a natural warming of
  both Earths lower atmosphere and Earths surface
  from solar radiation being absorbed and emitted
  by the atmosphere.
• Studies indicate that human activities for the
  past 200 years have had a huge impact on the
  greenhouse effect.
• Most of this is due to the carbon dioxide that
  we add to our atmosphere through the burning of
  fossil fuels such as coal, petroleum, and natural
  gas.

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Carbon Dioxide Concentrations Emissions
Climate Changes
The rapid increase in carbon dioxide
concentration since 1850 has closely followed the
increase in carbon dioxide emissions from the
burning of fossils fuels.
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Climate Changes
Human Impact on Climate Changes
? Global Warming

• As a result of increased levels of carbon
  dioxide and other greenhouse gases, global
  temperatures have increased. This increase is
  called global warming.
• How will these temperature changes affect the
  Earth?
• Warmer surface temperatures increase evaporation
  rates adding more moisture to our atmosphere
  magnifying the greenhouse effect even more.
• Temperature increases will also cause the polar
  ice caps to melt will cause a global rise in the
  levels of the ocean.
• Scientists also expect that weather patterns
  will change which will result in more severe
  hurricanes and droughts.

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Increases in Greenhouse Gases Changes in
Temperature
Climate Changes

• During the 20th Century the Earths surface
  temperatures have increased by 0.6C
• Scientists predict that by the year 2100 the
  temperatures will increase by 1.4C to 5.8C.
• Use the graph above to answer the final
  questions on your own.