Transcript Climate Change - University of San Diego

Climate Change – Other Factors
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Many factors affect global climate in multiple
ways
Ex – Clouds absorb re-radiated longwavelength radiation but also may reflect
incoming short-wavelength radiation
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Ex – Particles in the atmosphere reduce the reradiation of long-wavelength radiation but also
reflect incoming short-wavelength radiation
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Net effect is cooling
Net effect is probably warming at low levels but
cooling at high levels (e.g. following a large volcanic
eruption)
Uncertainty about impact of many factors
IPCC AR4
Climate Change – Effects
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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
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Negative
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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
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Negative
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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
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Negative
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Sea Level
Examples
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Estimated that sea level rise of 1 m would displace
15 million people in UK
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
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38% of food production tied to flood plains
Maldives – Highest elevation 24 m
Japan – Fishing rights around pinnacle
AOSIS (Alliance of Small Island States) – Strong
concerns about sea level rise
World Map – 100 m Sea Level Rise
http://vrstudio.buffalo.edu/~depape/warming/World100-8190.jpg
US East Coast –Sea Level Rise
1m
3m
http://vrstudio.buffalo.edu/~depape/warming/east.html
www.panoramio.com/photo/31807235
US East Coast –Sea Level Rise
10 m
30 m
http://vrstudio.buffalo.edu/~depape/warming/east.html
Climate Change – Effects
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Negative
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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
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Negative
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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
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Negative
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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
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
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Negative
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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
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Negative
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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
Climate Change – Effects
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Negative
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Ozone Holes
Global warming of the atmosphere translates to
stratospheric cooling
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Stratospheric cooling may enhance ozone destruction in
Antarctic and make phenomenon more common in
Arctic (Waibel et al. 1999)
Health
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Consistently elevated temperatures can lead to
immunosuppression
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Exacerbated by elevated levels of UV-B
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Ex – Mass mortality of animals in last 10 years due
to viral infections
- Seals in North Sea
- Lions in Serengeti (Africa)
- Horses in Australia
- Birds in western US
Allergies could worsen due to increased pollen
production, dust (desertification), mold (humidity)
Additional human mortality from severe summer heat
Climate Change – Effects
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Negative
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Tropical Pests and Diseases
Unusual weather favors opportunistic pests
while making life difficult for the predators
that typically control them
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Periods of anomalous weather tend to be followed
by outbreaks of disease
Many tropical diseases are transmitted by
animal vectors – insects, rodents
Climate Change – Effects
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Negative
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Tropical Pests and Diseases
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Cholera
1991 – Freighter from Asia emptied bilge tanks off
Peru during an ENSO event
Cholera in bilge water  plankton  shellfish 
humans
500,000+ infected; 5000+ dead
Hantavirus
Late 1980s/Early 1990s – Drought in SW US led to
increase in deer mouse population
Transmitted lethal form of pulmonary hantavirus
To date, hantavirus has appeared in 20 states;
100+ dead
Climate Change – Effects
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Negative
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Tropical Pests and Diseases
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Plague
1994 – Unusually long monsoon season in N India
followed by 90 days of temperatures > 100 oF
Heat drove rats into cities  Spread plague
$2 billion to combat problem; 63 dead
Dengue fever
1995 – Rising temperatures allowed a coastal
mosquito species to cross mountains and spread
across Costa Rica, carrying dengue fever
Reached as far north as Texas border
140,000+ people infected; 4000+ dead
Climate Change – Effects
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Negative
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Tropical Pests and Diseases
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Malaria
Most prevalent vector-borne disease (1-2 million
cases/year)
Transmitted by Anopheles mosquitoes
Warming could lead to
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Broader geographic range (estimate that +2oC could
expand range from 42 to 60% of land area)
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Higher metabolic rate  More food
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Faster maturation  More rapid reproduction
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Faster parasite life cycle
Potential spread into large urban areas (Nairobi, Kenya;
Harare, Zimbabwe) with immunologically naïve pop’ns
Projections are controversial and highly variable
Climate Change – Effects
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Positive
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Plant Growth
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Warmer temperatures and elevated concentrations
of CO2 lead to faster plant growth and greater food
production per acre
Elevated concentrations of CO2 should lead to
more efficient use of water, reduced runoff and
less water pollution
Enhanced plant growth should remove CO2 from
atmosphere at a faster rate (Gaia Hypothesis)
Agriculture
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Expansion of agricultural regions
Longer growing season in areas that currently are
marginal for agriculture
Climate Change – Effects
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Positive
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Rainfall Patterns
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Predictions of increased rainfall in major
agricultural regions, especially in northern
hemisphere
Reduced irrigation required for plants/crops
Increased precipitation should cause glaciers and
ice sheets to grow
Milder Winters
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Severe winters pose a health and safety risk
Fewer expenses associated with less severe
winter weather
III. Climate Change – Projections
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Complexity and uncertainty in climate
models
Response of earth climate system to a
forcing function
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Accumulation of CO2 in the atmosphere