IPCC AR4

I. I.Climate Change – Effects Climate change may have positive and negative effects for humans and ecosystems Media typically portrays climate change as negative

I. I.Climate Change – Effects A. A.Negative 1. 1.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

I. I.Climate Change – Effects A. A.Negative 1. 1.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. I.Climate Change – Effects A. A.Negative 1. 1.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)

US East Coast –Sea Level Rise 1 m3 m

I. I.Climate Change – Effects A. A.Negative 1. 1.Sea Level Caveats Sea level not rising in all areas Sea level rise began before Industrial Revolution

I. I.Climate Change – Effects A. A.Negative 2. 2.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 Trends

Source: U.S. Global Change Research Program

I. I.Climate Change – Effects A. A.Negative 1. 1.Sea Level 2. 2.Rainfall Patterns 3. 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)

Climate Change – Appropriate Scales Caveat: It’s important to consider climate change at appropriate scales (e.g. global vs. local) Link

I. I.Climate Change – Effects A. A.Negative 4. 4.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 CO 2 concentrations  pH of ocean

Chen et al. 2011

I. I.Climate Change – Effects A. A.Negative 4. 4.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 CO 2 concentrations  pH of ocean