The Atmosphere, Climate, and Global Warming

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Chapter 22

• The Atmosphere, Climate, and Global Warming

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The Atmosphere

• The thin layer of gas that envelops the Earth
• Chemical reactions
• Atmospheric circulation produces weather and
  climates

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Processes that remove things from the Atmosphere

• Sedimentation particles heavier than air
• Rainout washed out by rain, snow etc.
• Oxidation Formation of SO3
• Photodissociation- breaking up of Ozone

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Climate

• Climate
• the representative or characteristic atmospheric
  conditions for a region on Earth
• Microclimate
• The climate of a very small local area
• Urban Dust Dome
• Polluted urban air produced by the combination of
  lingering air and abundance of particulates and
  other pollutants in the urban air mass

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Climatic Change

• During the past 100 years, the mean global annual
  temperature has increased by .5 degrees Celsius
• During the past 100 years CO2 levels have
  increased. Coincidence?

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Core Case Study Studying a Volcano to Understand
Climate Change

• NASA scientist correctly predicted that the 1991
  Philippines explosion would cool the average
  temperature of the earth by 0.5Co over a 15 month
  period and then return to normal by 1995.

Figure 20-1
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Core Case Study Studying a Volcano to Understand
Climate Change

• The NASA model was correct.
• The success convince scientists and policy makers
  that climate model projections should be taken
  seriously.
• Other climate models have shown that global
  temperatures are likely to rise several degrees
  during this century.

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Global Warming

• A natural or human induced increase in the
  average global temperature of the atmosphere near
  the earths surface
• Natural global warming makes Earth livable 33
  deg C warmer.
• Water vapor is the main reason

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Global Warming cont.

• 4 factors
• Amount of sunlight Earth receives
• Amount of sunlight Earth reflects
• Retention of heat by atmosphere
• Evaporation and condensation of water vapor

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Electromagnetic Radiation and Earths Energy
Balance

• Electromagnetic spectrum
• The collection of all possible wavelengths of
  electromagnetic energy, considered a continuous
  range

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The Greenhouse Effect

• Greenhouse Effect
• The process of trapping heat in the atmosphere
• Water vapor and several other gases warm the
  Earths atmosphere because they absorb and emit
  radiation

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Greenhouse Gases

• Greenhouse Gases
• Gases that have a greenhouse effect
• Water vapor, carbon dioxide, methane, CFCs

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Global Warming

• Negative and Positive feedback cycles affect the
  atmosphere
• Increase in emission of greenhouse gasses
• Solar Forcing, Natural Cycles, Aerosols (global
  dimming), Volcanic Eruptions, El Nino

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Negative Feedbacks

• Increased Algae growth absorb CO2. How would
  this affect G.W.? Ecosystems?
• Increased CO2 levels faster plant growth
• More precipitation. In Polar Regions more ice
  cap ? more reflection
• More cloud Cover more reflection

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Positive Feedback

• Increased Evaporation more vapor and more
  warming
• Methane from melting permafrost or glaciers
• Reduction of summer snow caps less reflection
• Warmer temps. ? more A/C use ? more CO2

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CGCM of the Earths Climate

• Simplified model of major processes that interact
  to determine the average temperature and
  greenhouse gas content of the troposphere.

Figure 20-6
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Sun
Troposphere
Cooling from increase
Green- house gases
Heat and CO2 emissions
Aerosols
CO2 removal by plants and soil organisms
CO2 emissions from land clearing, fires, and decay
Heat and CO2 removal
Warming from decrease
Ice and snow cover
Shallow ocean
Land and soil biotoa
Long-term storage
Natural and human emissions
Deep ocean
Fig. 20-6, p. 469
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Troposphere
Ice and snow cover
Shallow ocean
Land and soil biotoa
Natural and human emissions
Deep ocean
Stepped Art
Fig. 20-6, p. 469
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How Do We Know What Temperatures Were in the Past?

• Scientists analyze tiny air bubbles trapped in
  ice cores learn about past
• troposphere composition.
• temperature trends.
• greenhouse gas concentrations.
• solar, snowfall, and forest fire activity.

Figure 20-3
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Global Warming how much?

• Change is overall temp. 1-2 0C by 2030
• Changes magnified at poles due to reduced
  reflection of sun by ice

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Effects of Global Warming

• Changes in climatic patterns
• semi arid land may become drier other areas may
  become wetter. Prime farming area will move
  North to Canada vs US Prairie today. Resulting in
  reduced food production
• Less snow pack means less runoff for California
  as well as for India and China
• Not all scientists agree with these predictions
  and predictions have great variability

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Effects of Global Warming

• Rise in sea level due to thermal expansion and
  ice melt.
• Amount of rise is variable . Most probable is
  20-40 cm by 2100. Many people live on coast.
• Note Manhattan and Florida will not be
  completely flooded at this level

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CLIMATE CHANGE AND HUMAN ACTIVITIES

• Evidence that the earths troposphere is warming,
  mostly because of human actions
• The 20th century was the hottest century in the
  past 1000 years.
• Since 1900, the earths average tropospheric
  temperature has risen 0.6 C.
• Over the past 50 years, Arctic temperatures have
  risen almost twice as fast as those in the rest
  of the world.
• Glaciers and floating sea ice are melting and
  shrinking at increasing rates.

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Effects of Global Warming

• Changes in biosphere
• Arrival of Spring will be earlier and Fall later.
  Species will have to adapt ? if they can or they
  will perish
• Will polar bears be able to survive on thin ice?
• Mosquito population expands
• Tundra size reduced or eliminated

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EFFECTS OF GLOBAL WARMING

• A warmer climate would have beneficial and
  harmful effects but poor nations in the tropics
  would suffer the most.
• Some of the worlds floating ice and land-based
  glaciers are slowly melting and are helping warm
  the troposphere by reflecting less sunlight back
  into space.

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EFFECTS OF GLOBAL WARMING

• Between 1979 and 2005, average Arctic sea ice
  dropped 20 (as shown in blue hues above).

Figure 20-8
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Russia

North pole
Greenland
Alaska (U.S.)
Canada
Fig. 20-8, p. 474
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Rising Sea Levels

• During this century rising seas levels are
  projected to flood low-lying urban areas, coastal
  estuaries, wetlands, coral reefs, and barrier
  islands and beaches.

Figure 20-10
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Adjustments to Global Warming

• Mitigate warming through reduction of greenhouse
  gasses
• Energy conservation
• Alternative energy sources
• Danger rapid climatic change

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