Transcript Sep 27 - University of San Diego

IPCC AR4
Climate Change – Effects
I.
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Climate change may have positive and
negative effects for humans and
ecosystems
Media typically portrays climate change
as negative
Climate Change – Effects
I.
A.
Negative
1.
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Sea Level
Warming  melting of glaciers and ice caps
 sea level rise
Warming  thermal expansion of water 
additional sea level rise
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Melting of all ice  sea level rise of ~70 m
http://www.epa.gov/climatechange/science/futureslc_fig1.html
Climate Change – Effects
I.
A.
Negative
1.
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Sea Level
Since 1880, sea level has been rising at a
rate of ~15 cm century-1
•
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Accelerating since 1940s
Rates at ends of glacial periods ~40 cm century-1
Sizes of polar ice sheets fairly constant over
last century (some shrinkage in Antarctica)
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Temperate glaciers have shrunk visibly
Warming should lead to increased atmospheric
moisture and precipitation, which should cause a
net growth of polar ice caps
Climate Change – Effects
I.
A.
Negative
1.
•
Sea Level
Examples
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Estimated that measures to protect low lying land
in US from damage would cost > $100 billion
Bangladesh – More than 17 million people live less
than 1 m above sea level
•
38% of food production tied to flood plains
AOSIS (Alliance of Small Island States) – Strong
concerns about sea level rise
Maldives – Highest elevation 24 m
Japan – Fishing rights around pinnacle
Social justice issue (Global Humanitarian Forum)
US East Coast –Sea Level Rise
1m
3m
http://vrstudio.buffalo.edu/~depape/warming/east.html
www.panoramio.com/photo/31807235
Climate Change – Effects
I.
A.
Negative
1.
•
Sea Level
Caveats
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Sea level not rising in all areas
Sea level rise began before Industrial Revolution
http://www.epa.gov/climatechange/science/recentslc.html
http://sealevel.colorado.edu/files/current/sl.pdf
Climate Change – Effects
I.
A.
Negative
2.
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Rainfall Patterns
Warming should lead to
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Reduced precipitation at low latitudes
Increased precipitation at high latitudes
Examples
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Reduced snowpack in Sierra Nevada Mountains
due in part to rainfall instead of snow
Drought in many parts of the world
Annual Trends
1901-2005
http://www.epa.gov/climatechange/science/recentpsc_precipanom.html
Source: U.S. Global
Change Research
Program
Climate Change – Effects
I.
A.
Negative
1.
2.
3.
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Sea Level
Rainfall Patterns
Storms
Warming should lead to
•
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More severe storms
Greater storm frequency
May not occur if temperature differential
between poles and equator weakened, not
strengthened (Lindzen)
www.ncdc.noaa.gov/oa/climate/research/cei/cei.html
Climate Change – Appropriate Scales
•
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Caveat: It’s important to consider climate
change at appropriate scales (e.g. global
vs. local)
Link
Climate Change – Effects
I.
A.
Negative
4.
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Species Extinction & Ecosystem Changes
Shifting climatic zones could expand ranges of
warmth-tolerant species and contract ranges of
warmth-intolerant species
•
•
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Populations of various species might be isolated,
leading (eventually) to speciation (Good?)
Within an ecosystem, some species will be more
sensitive to climate change than others
•
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Colder-living species might be displaced poleward as
well as upward in elevation
Species unable to adapt or move would go extinct
Predicted rates of 16.9 km/decade and 11.0 m/decade
(Chen et al. 2011)
Species composition of ecosystems almost certainly
will change
Changes in CO2 concentrations  pH of ocean
Chen et al. 2011
Climate Change – Effects
I.
A.
Negative
4.
•
Species Extinction & Ecosystem Changes
Shifting climatic zones could expand ranges of
warmth-tolerant species and contract ranges of
warmth-intolerant species
•
•
•
•
Populations of various species might be isolated,
leading (eventually) to speciation (Good?)
Within an ecosystem, some species will be more
sensitive to climate change than others
•
•
•
Colder-living species might be displaced poleward as
well as upward in elevation
Species unable to adapt or move would go extinct
Predicted rates of 16.9 km/decade and 11.0 m/decade
(Chen et al. 2011)
Species composition of ecosystems almost certainly
will change
Changes in CO2 concentrations  pH of ocean