Chapter 18: Global Climate
Change
Climate
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area's long-term atmospheric conditions
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temperature
humidity
wind
precipitation
barometric pressure
solar radiation
global climate change sees all these factors but
considering the whole planet
Global Warming
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increase in Earth's average surface
temperature only
Rate of Atmospheric Changes
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climate varies naturally overtime
the rate has increased
fossil fuel combustion and deforestation
Factors that Influence Climate
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Milankovitch cycles
affect intensity of solar radiation
cause long-term temperature changes like
glaciation
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axial wobble→ 19 to 23,000 year cycle
variation in tilt→ 41,000 year cycle
variation in orbit→ 100,000 year cycle
Factors that Influence Climate
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ocean absorption
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CO2 is soluble in ocean water
but as temperature increases solubility decreases
phytoplankton absorbs some in photosynthesis
but not enough to compensate the extra CO2
produced today
positive feedback effect
Factors that
Influence Climate
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ocean currents
El Niño
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air pressure decreases in western Pacific
weakens the equatorial winds
warm water flows east towards America
shuts down delivery of nutrients
fish population plumbs
ocean birds, reptiles and mammals are also affected
causes billions of economical losses
www.noaa.gov
Factors that
Influence Climate
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La Niña
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opposite of El Niño
cold waters extend to the west
www.noaa.gov
El Niño/La Niña occur in cycles but these have
become irregular
Scientists are investigating if there is any relation
between irregularity of phenomena and air/water
temperature increases
Thermohaline Circulation
www.aw-bc.com/Withgott
Thermohaline Circulation
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interruption might trigger rapid climate
change (hypothesis)
data suggest circulation is slowing down
Study of Climate Change
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proxy indicators: indirect evidence
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ice cores
tree rings
sediment beds
coral reef
Study of Climate Change
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direct atmospheric sampling
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studies present-day climate
measures conditions of the atmosphere
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concentrations of CO2
monitoring of temperature
Study of Climate Change
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Climate Models
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simulations
mathematical
sophisticated computer programs that combine
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atmospheric circulation
ocean circulation
atmosphere-ocean interactions
feedback
old data is used to see if the model works before it is
applied
Current Climate Change Impacts
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international panel of scientists (IPCC)
Fourth Assessment Report of 2007 (fig.
18.12)
contains thousands of studies
includes some predictions
addresses impacts of current and future
climate changes
discusses possible strategies
Temperature Increase
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most of the increase occurred in the last few
decades
1995-2006 were among the warmest on record
the number of heat waves have increased
a temperature increase of 0.2ºC is expected per
decade if there is no control of emissions
IPCC predicts that by 2100 temperature will rise 1.84ºC depending on the emission scenario
Temperature Increase
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Arctic changes of up to 3ºC are causing:
ice melting earlier
forming later
ice area is decreasing
thinner ice
no food for Inuit people
no food for polar bears
permafrost is melting
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Projected Temperature Changes
for the decade of 2090-2099
www.aw-bc.com/Withgott
IPPC calculates an increase of 0.1ºC per decade during the 21st century
If we don't control the emissions it might get to an increase of 4ºC
Ocean temperature is also increasing causing more intense hurricanes
Changes in Precipitation
www.aw-bc.com/Withgott
It is predicted to increase at high latitudes and decrease at low and middle
Will worsen water shortages near the tropics
Away from the tropics heavy precipitation will become more frequent
increasing chances of flooding
Droughts will become more severe and frequent
Melting Ice and Snow
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risks of sudden floods
ice dams burst
reduction of summertime water supply
Artic/Antarctic ice surface is decreasing
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resulting in larger darker ocean surfaces which capture heat
and melt the ice faster
more dark surfaces on Earth reduces the albedo effect (light
reflection)
as a result Earth's surface increases in temperature
positive: new shipping lanes and possible sites for oil and
gas exploration
Rising Sea Levels
1938
1957
1972
1988
Backwater National Wildlife Refuge in Maryland
marsh loss can occur if the rise is so fast that plants can't adapt
Rising Sea Levels
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increase in level worldwide (17cm=6.7 in)
caused by
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melting of ice
increase in runoff
increase in temperature→causes expansion of
the volume of water already there
Problems with Rising Sea Levels
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beach erosion
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Florida, Washington, California, Texas, etc.
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coastal floods
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Venice, Italy
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intrusion of salt water into aquifers
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Los Angeles
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loss of wetlands (mangroves)
Guayaquil, Ecuador
1985 & 2000
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loss of coral reefs
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Maldives
possible evacuations and migration of people
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Island nations of Tuvalu and Maldives
Climate Change Effects on Organisms
& Ecosystems
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alterations of the environment affect living
organisms
adaptations take generations to acquire
Changes Attributed to Climate Change
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temperature-dependant
plants blooming timing
animals breeding timing
birds migration timing
insects hatching timing
plants and animals are migrating north or
higher elevations
bleaching of corals
Societal Impacts
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Agriculture Related
earlier crop planting
shift of seasons
droughts and floods become more severe
predictions say production may increase but only
temporarily
tropical and subtropical regions will lower production
due to drought
hunger will increase
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Forestry
longer & drier fire season
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El Niño 97-98
invasive species are more common
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Asian long horned beetle
zebra mussel has arrived to Texas (4/09)
found in lake Texoma
zebra mussel
insect and diseases are more frequent
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elm trees
www.aw-bc.com/Withgott
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Health Issues
Deaths attributed to hot weather
respiratory diseases
more frequent
expansion of tropical diseases
floods overcoming sewage treatment
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cholera
drowning more probable
hunger/ malnourished
Economics
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people's perception of greenhouse effects has
shifted
insurance companies began noticing increase in
weather related disasters
industry also changed its point of view
An Inconvenient Truth helped spark the interest
companies are asking for legislation to require
significant reduction in greenhouse gas emittions
Responding to Climate Change
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mitigation or adaptation?
mitigation: pursue actions that reduce
greenhouse gas emittions
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energy efficiency
switching to clean renewable energy
farm practices that protect soil and water quality
prevent deforestation
recovery of gasses from landfills
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adaptation: lessen the impact of future
climate changes
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seawall in Galveston
restricting coastal development
adjusting farm practices to drought conditions
modification of water management due to water
conditions (floods, drought and salt intrusion)
Electricity Generation: Source of
Greenhouse Gasses
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it is the largest source (40%) of greenhouse
gasses in the U.S.
69% of the electricity in the U.S. is generated
by fossil fuels. 50% is from coal.
ways to lessen the amount of fossil fuels
used
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encouraging conservation
switching to cleaner and renewable sources
Conservation and Efficiency: Saves
Money in the Long Run
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new technologies
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high-efficiency light bulbs for example
ethical choices
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EPA's Energy Star Program
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more efficient electric appliances
efficient heating and cooling systems
efficient office equipment
turn off lights when not in use
turn off equipment when not in use
Sources of Electricity: Cleaner is
Better
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altering the types of energy we use
coal→oil→natural gas
natural gas produces half the emissions that coal
produces
carbon sequestration (or carbon capture) will reduce
the CO2 emitted to the air
use of OTHER energy sources
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nuclear power
wind power
hydroelectric
ocean tides
geothermal
photovoltaic
Transportation
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second-largest source of greenhouse gasses
1/3 of the average American city is devoted
to car use
average American family makes 10 trips/day
in the U.S. $200 million is spend daily in
construction and repairs
Typical Automobile is Inefficient
www.aw-bc.com/Withgott
Automotive Technology
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fuel-efficient vehicles
hybrids
fully electric
alternative fuels (hydrogen cells)
Public Transportation
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it is a lifestyle choice
car use decreases if living near their workplace
cities are working on the use of mass transit
people are including bike or walk
it is not accessible to everyone
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Arlington refuses to include the train and bus system
Allen refuses to include the DART train system
Strategies to Reduce Emissions
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double fuel efficiency in vehicles
decrease the miles you drive daily
maximize efficiency in buildings
double efficiency in coal power plants
switch from coal to natural gas
capture and store carbon dioxide (sequestration)
increase nuclear power production (3x)
increase wind (50x) & solar (700x) energy production
halt tropical deforestation
adopt conservation tillage on croplands
Mandates, Incentives or Both?
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commandment-and-control policy
mandates are often resisted by industry
incentives may be more effective
whatever desition it has to be
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fair
economically palatable
effective
enforceable
International Treaties
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1992 U.N. Framework Convention on
Climate Change- voluntary approach
by 2006
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U.S. has increased its emissions by 17.9%
Germany decreased its emissions by 17.2%
U.K. dropped its emissions by 14.3%
1997 Kyoto Protocol
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mandates reduction of emittions to those of 1990
reduction must be accomplished by 2008-2012
U.S. refused to ratify accusing China and India
of polluting without having to follow the protocol
creating resentment with allies
emittions had increased 11% worldwide by 2004
Climate Change Policies from Cities
and States
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in responce to inaction from the G.W. Bush
administration and Congress
"meet or beat" Kyoto Protocol guidelines
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mayors of 600 cities
urging state and federal government to act
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California passed the Global Warming Solutions Act in
2006- 25% reduction of greenhouse gasses by 2020
cap-and-trade program in the NE
Carbon Offset: Key to Mitigating
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voluntary payment
pays the entity that is willing to reduce
emissions that one in not willing to do
becoming very popular
carbon-neutrality: no net carbon is emitted
now it may not be as efficient as thought
has to be transparent and enforceable
Carbon Footprint
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individual everyday life choices
reduce the emissions you create
transportation
EPA Star Program
THE END
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