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

II. II.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

II. II.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

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

World Map – 100 m Sea Level Rise

US East Coast –Sea Level Rise 1 m3 m

US East Coast –Sea Level Rise 10 m30 m

II. II.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

II. II.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

II. II.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

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

II. II.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

II. II.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

II. II.Climate Change – Effects A. A.Negative 5. 5.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. 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. II.Climate Change – Effects A. A.Negative 7. 7.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. II.Climate Change – Effects A. A.Negative 7. 7.Tropical Pests and Diseases a. 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; dead b. b.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. II.Climate Change – Effects A. A.Negative 7. 7.Tropical Pests and Diseases c. c.Plague 1994 – Unusually long monsoon season in N India followed by 90 days of temperatures > 100 o F Heat drove rats into cities  Spread plague $2 billion to combat problem; 63 dead d. 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; dead

II. II.Climate Change – Effects A. A.Negative 7. 7.Tropical Pests and Diseases e. 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 +2 o C 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. II.Climate Change – Effects B. B.Positive 1. 1.Plant Growth Warmer temperatures and elevated concentrations of CO 2 lead to faster plant growth and greater food production per acre Elevated concentrations of CO 2 should lead to more efficient use of water, reduced runoff and less water pollution Enhanced plant growth should remove CO 2 from atmosphere at a faster rate (Gaia Hypothesis) 2. 2.Agriculture Expansion of agricultural regions Longer growing season in areas that currently are marginal for agriculture

II. II.Climate Change – Effects B. B.Positive 3. 3.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. 4.Milder Winters Severe winters pose a health and safety risk Fewer expenses associated with less severe winter weather

III. III.Climate Change – Projections Complexity and uncertainty in climate models Response of earth climate system to a forcing function Accumulation of CO 2 in the atmosphere