IPCC AR4

I. Climate Change – Effects

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

• Media typically portrays climate change as negative

I. 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

I. 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

I. Climate Change – Effects

A. Negative1. Sea Level• Examples

• 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)

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

US East Coast –Sea Level Rise1 m 3 m

www.panoramio.com/photo/31807235

I. 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

I. 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

I. 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 (Lindzen)

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

I. 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

I. 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