I. Climate Change – Other Factors

• Many factors affect global climate in multiple ways

• Ex – Clouds absorb re-radiated long-wavelength radiation but also may reflect incoming short-wavelength radiation

• Net effect is cooling

• Ex – Particles in the atmosphere reduce the re-radiation of long-wavelength radiation but also reflect incoming short-wavelength radiation

• 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

II. Climate Change – Effects

• Climate change may have positive and negative effects for humans and ecosystems

• Media typically portrays climate change as negative

II. Climate Change – Effects

A. Negative1. Sea Level• Warming melting of glaciers and ice caps

sea level rise• Warming thermal expansion of water

additional sea level rise• Melting of all ice sea level rise of ~70 m

http://www.epa.gov/climatechange/science/futureslc_fig1.html

II. Climate Change – Effects

A. Negative1. Sea Level• Since 1880, sea level has been rising at a

rate of ~15 cm century-1

• 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)

• Temperate glaciers have shrunk visibly• Warming should lead to increased atmospheric

moisture and precipitation, which should cause a net growth of polar ice caps

II. Climate Change – Effects

A. Negative1. Sea Level• Examples

• 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• 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

http://vrstudio.buffalo.edu/~depape/warming/World100-8190.jpg

World Map – 100 m Sea Level Rise

http://vrstudio.buffalo.edu/~depape/warming/east.html

US East Coast –Sea Level Rise1 m 3 m

www.panoramio.com/photo/31807235

http://vrstudio.buffalo.edu/~depape/warming/east.html

US East Coast –Sea Level Rise10 m 30 m

II. Climate Change – Effects

A. Negative1. Sea Level• Caveats

• 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

II. Climate Change – Effects

A. Negative2. Rainfall Patterns• Warming should lead to

• Reduced precipitation at low latitudes• Increased precipitation at high latitudes

• Examples• Reduced snowpack in Sierra Nevada Mountains

due in part to rainfall instead of snow• Drought in many parts of the world

Annual Trends1901-2005

http://www.epa.gov/climatechange/science/recentpsc_precipanom.html

Source: U.S. Global Change Research Program

II. Climate Change – Effects

A. Negative1. Sea Level

2. Rainfall Patterns

3. Storms• Warming should lead to

• 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

• Caveat: It’s important to consider climate change at appropriate scales (e.g. global vs. local)

• Link

II. Climate Change – Effects

A. Negative4. Species Extinction & Ecosystem Changes• Shifting climatic zones could expand ranges of

warmth-tolerant species and contract ranges of warmth-intolerant species

• 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)• 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• Species composition of ecosystems almost certainly

will change• Changes in CO2 concentrations pH of ocean

Chen et al. 2011

II. Climate Change – Effects

A. Negative4. Species Extinction & Ecosystem Changes• Shifting climatic zones could expand ranges of

warmth-tolerant species and contract ranges of warmth-intolerant species

• 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)• 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• Species composition of ecosystems almost certainly

will change• Changes in CO2 concentrations pH of ocean

II. Climate Change – Effects

A. Negative5. Ozone Holes• Global warming of the atmosphere translates to

stratospheric cooling• Stratospheric cooling may enhance ozone destruction in

Antarctic and make phenomenon more common in Arctic (Waibel et al. 1999)

6. Health• Consistently elevated temperatures can lead to

immunosuppression• Exacerbated by elevated levels of UV-B• 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

II. Climate Change – Effects

A. Negative7. Tropical Pests and Diseases• Unusual weather favors opportunistic pests

while making life difficult for the predators that typically control them

• Periods of anomalous weather tend to be followed by outbreaks of disease

• Many tropical diseases are transmitted by animal vectors – insects, rodents

II. Climate Change – Effects

A. Negative7. Tropical Pests and Diseases

a. 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+ deadb. 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

II. Climate Change – Effects

A. Negative7. Tropical Pests and Diseases

c. 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

d. 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

II. Climate Change – Effects

A. Negative7. Tropical Pests and Diseases

e. Malaria• Most prevalent vector-borne disease (1-2 million

cases/year)• Transmitted by Anopheles mosquitoes• Warming could lead to

• Broader geographic range (estimate that +2oC could expand range from 42 to 60% of land area)

• Higher metabolic rate More food• Faster maturation More rapid reproduction• 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

II. Climate Change – Effects

B. Positive1. Plant Growth

• 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)

2. Agriculture• Expansion of agricultural regions• Longer growing season in areas that currently are

marginal for agriculture

II. Climate Change – Effects

B. Positive3. Rainfall Patterns

• 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

4. Milder Winters• Severe winters pose a health and safety risk• Fewer expenses associated with less severe

winter weather

III. Climate Change – Projections

• Complexity and uncertainty in climate models

• Response of earth climate system to a forcing function

• Accumulation of CO2 in the atmosphere