Chapter #21
Global Climate
Change
Overview
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Introduction to Climate Change
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Causes of Global Climate Change
Effects of Climate Change
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Melting Ice and Rising Sea Level
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Changes in Precipitation Patterns
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Effects on Organisms
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Effects on Human Health
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Effects on Agriculture
Dealing with Global Climate Change
Climate ChangeMean 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
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
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Greenhouse gas concentrations increasing
Causes
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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 Change- Melting 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 self-interests
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 ChangeRelationship Between Mitigation and
Adaptation
Dealing with Global Climate
Change- Mitigation
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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
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Move inland
Construct dikes
and levees
Adapt to shifting
agricultural zones
NYC sewer line
“There were
rumors of
unfathomable
things, and
because we
could not
fathom them we
failed to believe
them, until we
had no choice it
was too late.”
Ozone Depletion
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Stratospheric ozone
UV light
Chemical processes
Environmental effects
Solutions
Atmosphere
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Stratospheric ozone
20-30 km altitude
19 mi at equator, 9 mi at the poles
400 ppb
Ozone shield
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99% of all UV is absorbed
(UVC and most UVB)
UVA is not affected by
ozone
Production of ozone
Measurement of Ozone
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Dobson units: 1 ppb
ozone
Survey began in 1957 over
the Antarctic
Taken in October,
springtime
1957-1970: 300 DU
150 DU by 1986
Ozone and CFC’s
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Molina and Rowland in 1974
CFC’s are stable
Long residence in lower
atmosphere
UV radiation breaks down CFC
and releases Cl
Cl reacts with O3
Increase UVB at the surface
Formation and destruction of ozone
Emissions
Usage
2003
Ozone Hole
Polar Stratospheric clouds
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Polar winter formation
Have polar vortex
Isolated air mass
Nitrogen oxides held in
clouds as nitric acid
NO3 particles grow and
fall out
Facilitates ozone depleting
reactions
Polar vortex
In Springtime, sunlight
Returns
No nitrate to form CloNO2
Environmental effects
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UV damage to DNA
Skin cancer
Cataracts
Suppression of immune system
Ecosystem:
Primary producers
Food chains
Development in aquatic larva
Managing ozone depletion
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Montreal protocol, Sept 1987–
Production of CFC elimination
Economic gap
Replacements: HFC and HCFC
Shorter lifetime, less reactive
Collection and reuse (no
venting)
Expensive replacements
Climate Change
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Climate Swings
Greenhouse gases
Evidence
Predictions
Control
Historic Climate shifts
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Milankovitch cycles: shifts in earth‘s orbit and tilt
Volcanic activity: Mt. Toba
El Nino/Southern Oscillation
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Trade winds keep warm water in W.
Pacific. La Nina
El Nino: Shift in tropical
depression
Northern Jet stream splits changes
rainfall patterns
Pacific decadal oscillation: warm
water in northern pacific moves
back and forth.
Cool water in north help Alsaka
salmon runs, warm off coast and
then switches.
Human Activities
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Industrialization
CO2 increased 31%, CH4 inc 151%, N2O inc 17% over since preindustrial times.
40% of excess CO2 absorbed by oceans
Methane a big problem
Evidence of Climate Change
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Avg global temperature has climbed 0.6oC over last century
Arctic sea ice is 40% thinner, Antarctic glaciers are retreating 50m/yr.
Alpine glaciers are retreating
Ocean acidification
Sea level has risen
Changes in animal behavior, breeding cycles
Storm frequency and intensity are increasing
Larsen B ice shelf-- Antarctica
Consequences
Arctic sea ice
Alpine glaciers
Predictions
Predicted warming with doubling of
CO2
Sugar maple range
Controls
Reduction of Carbon Emissions
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Burn less fossil fuel: Turn down your thermostat
Plant Trees for shade and CO2 uptake
Insulate your house
Replace old appliances
Use compact fluorescence light bulbs
Use renewable energy