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Chapter 21
Global Climate Change
Overview of Chapter 21
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Introduction to Climate Change
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Effects of Climate Change
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Causes of Global Climate Change
Melting Ice and Rising Sea Level
Changes in Precipitation Patterns
Effects on Organisms
Effects on Human Health
Effects on Agriculture
Dealing with Global Climate Change
Introduction to Climate Change-
Mean Annual Global Temperature 1960-2005
Climate Change Terminology
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Greenhouse Gas
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Positive Feedback
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Change in some condition triggers a response that
intensifies the changed condition
Infrared Radiation
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Gas that absorbs infrared radiation
Ex: Carbon dioxide, methane, nitrous oxide,
chlorofluorocarbons and tropospheric ozone
Radiation that has a wavelength that is longer than that
of visible light, but shorter than that of radio waves
Greenhouse Effect
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Increase of heat in a system where energy enters
(often as light), is absorbed as heat, and released
sometime later
Introduction to Climate Change
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Evidence for Climate Change
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11 of the 12 years between 1995 and 2006
were among the twelve warmest years since
the mid-1800s
Phenological spring in N. hemisphere now comes
6 days earlier
Warming is not due to natural causes
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Human produced greenhouse gases are most
plausible explanation
Causes of Climate Change
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Greenhouse gas concentrations increasing
Causes of Climate Change
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Increased
concentration of
CO2 (right)
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Burning fossil fuels
in cars, industry and
homes
Deforestation
Burning of forests
Greenhouse Effect
Other Pollutants Cool the Atmosphere
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Atmospheric Aerosols tend to cool the
atmosphere
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Both human and natural sources
Tiny particles that remain in troposphere for
weeks or months
Contain many chemicals, but often contain
sulfur
Complicates models of climate change
Climate Models
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Climate affected by:
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winds, clouds, ocean currents, and albedo
Used to explore past climate events
Advanced models can project future
warming events
Models are only as good as the data and
law used to program them
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They have limitations
Climate Models
Effects of Global Climate Change
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Ocean as CO2 sink - excess CO2 is starting
to harm ocean life
Effects of Global Climate ChangeMelting Ice and Rising Sea Levels
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Sea level rise caused in 2 ways
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Thermal Expansion
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Melting of land ice
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Water expands as it warms
Retreat of glacier and thinning of ice at the poles
Melting has positive feedback
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Increased melting decreases ice, which
decreases albedo leading to further warming
Melting Ice and Rising Sea Levels
1957
1998
Case-In-Point Impacts in Fragile Areas
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Eskimo Inuit live
traditional life dictated
by freezing climate
Climate change is altering
their existence
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Wildlife are smaller or
displaced
Reduced snow cover and
shorter river ice seasons
Thawing of permafrost
(right)
Effects of Global Climate ChangeChanging Precipitation Patterns
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Some areas will get more water, some
areas will have greater droughts
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Ex: Hurricanes will likely get stronger
Effects of Global Climate ChangeEffects on Organisms
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Zooplankton in parts of California Current
have decreased by 80% since 1951
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Decline in krill around Antarctica
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Effecting entire food chain
Caused decrease in penguin populations
Species have shifted their geographic
range
Migrating birds are returning to summer
homes earlier
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Food is not available at this time
Effects on Organisms - Coral Reefs
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Coral reefs can be bleached (right) due to
increase in water temperature
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Affects coral symbiotes and makes them more
susceptible to diseases to which they would
otherwise be immune
Effect on Organisms - Vegetation
Beech Tree Range
Effects on Human Health
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Increased number of heat-related
illnesses and deaths
Effects on Agriculture
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Difficult to anticipate
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Productivity will increase in some areas and decrease in
others
Rise in sea level will inundate flood plains and
river valleys (lush farmland)
Effect on pests is unknown
Warmer temperatures will decrease soil
moisture- requiring more irrigation
Location (i.e. elevation and altitude) where
certain crops can be grown may have to change
International Implications
of Climate Change
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Developed vs.
Developing countries
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Differing selfinterests
Differing ability to
meet the challenges
of climate change
Dealing with Global Climate Change
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To avoid the worst of climate change, CO2
levels must be stabilized at 550ppm
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50% higher than current levels
Two ways to attempt to manage climate
change
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Mitigation
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Focuses on limiting greenhouse gas emissions to
moderate global climate change
Adaptation
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Focuses on learning to live with to the environmental
changes and societal consequences brought about by
global climate change
Dealing with Global Climate Change-
Relationship Between Mitigation and Adaptation
Dealing with Global Climate ChangeMitigation
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Locate/invent alternative fuels to fossil
fuels
Increase efficiency of cars and trucks
Sequestering carbon before it is emitted
Plant and Maintain trees to naturally
sequester carbon
Dealing with Global Climate ChangeAdaptation
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Rising sea levels and coastal populations
• Move inland
• Construct dikes and levees
Adapt to shifting agricultural zones
NYC sewer line
International Efforts to Reduce
Greenhouse Gas Emission
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Kyoto Protocol
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Legally binding
Provides operational rules on reducing
greenhouse gases
US and Australia have not signed it- it will be
difficult to implement without US backing