Bio 101 - Lecture 18

Bio 101 - Lecture 18 - Announcements MakeMake-up for Quiz...

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Unformatted text preview: Announcements MakeMake-up for Quiz 8: Friday, Mar. 7, 4:15, 251 Jennings Student Evaluation of Instruction (SEI) responses are being collected SEI) ONLINE SALG (Student Assessment of Learning Gains) fill it out and earn 4 extra credit points 1 Endocrine Disrupting Chemicals (EDCs) Chemicals that interfere with normal functioning of the endocrine (hormone) system What kinds of chemicals? PBT chemicals (PCBs, dioxins, DDT) Herbicides (2 4-D, atrazine?) (2,4(2,4 D Fungicides Detergents Birth control pills (ethylene estradiol) Organometals (tributyltin) Very low level exposure causes effects Endocrine disrupting chemicals Mechanism: mimic reproductive hormones estrogen and testosterone, causing physical changes and physiological imbalances Effects: Imposex both male and female sex organs Feminization of males and masculinization of females Molluscs very sensitive Fish in waters receiving sewage treatment plant effluent Imposex in amphibia Herring gulls same sex parents, nest abandonment Eagles fail to show nesting behaviour, abandon young Sterility, still births Deformities Northern Leopard Frog Deformities in amphibia What effects on wildlife? Lake Apopka, FL DDT spills and leaks Alligator population declines 90% Size does matter "teeny weenies"; decreased penis teeny weenies ; size, no reproduction Low levels of circulating testosterone in male alligators; as low as females Decreased fertility Great Lakes region Northern Leopard Frog [Rana pipiens] [Rana pipiens] Reduced populations of lake trout, mink, otters Many developmental deformities 2 What effects on wildlife? St. Lawrence estuary Beluga whales population declines Decreased immune system function increased disease incidence: tumors, skeletal abnormalities p Cases of true hermaphroditism Extremely high levels of fat soluble chemicals in whale calves at birth, in juveniles All transfer in milk and across placenta Why are polar bears victims of PCB contamination? LongLong-range aerial transport of PCB All chemicals have capacity to become volatile, escape to atmosphere Global wind patterns carry PCBs (and DDT) to Arctic and Antarctic, even though they have never been used there Accumulate in food webs May be responsible for reproductive failures in polar bears, seals Seals in Baltic Sea population crashes Increased disease outbreaks due to immune system dysfunction Are we seeing the same effects in humans? Air warms, picks up some moisture, ascends, cools, then gives up moisture. The cooled, drier air descends. Air at the equator warms, picks up much moisture, ascends to cool altitudes; ltit d then it gives up moisture (as precipitation). The cooled, drier air descends. Air warms, picks up some moisture, ascends, cools, then gives up moisture. Cooled, dry air descends. easterlies (winds from the east) westerlies (winds from the west) Why are polar bears victims of PCB contamination? Northern Florida North Africa northeast tradewinds (doldrums) southeast tradewinds westerlies easterlies Cooled, dry air descends. b Deflections in the initial pattern near Earth's surface. Fig. 43-3, p.756 Southern Australia South Africa a Initial pattern of air circulation as air masses warm and rise, then cool and fall. Different perspectives Our very future is threatened by these chemicals "Our Stolen Future" Theo Colburn "The Estrogen Effect" Deborah Cadbury The Effect What is global climate change? and Why should I care? Industry perspective Endocrine disruption in humans by chemicals has not been proven and effects of natural estrogens overshadow any effects from xenobiotic estrogens 3 CO2 and temperature over the last 45 yr on Hawaii's Mauna Loa peak Question 1: Is global climate change really happening? CO2: +14% Temp: +0.5o Temperature over the last 150 yr The paleoclimate record shows a clear correlation between changes i h in atmospheric CO2 and changes in global average temperature Source: IPCC, 2001 Retreating Greenland Ice Observation: Snow cover and ice extent have decreased (NASA, Goddard Space Flight Center) 4 Changes in ice volume Observation: Global average sea level has risen and ocean heat content has increased Studies Supporting Climate Change Question 2: So what's causing global what s climate change? Source: IPCC, 2001 Carbon cycle Processes and reservoirs X Deforestation Increased CO2 due to combustion of fossil fuels and wood Fig. 20.10a 5 CO2 concentrations are now 30% higher than they were in pre-industrial times. pre- Question 3: What are the potential effects of climate change? Potential Climate Change Impacts Temperature increase Precipitation variable Sea Level Rise Source: EPA Potential Climate Change Impacts Health WeatherWeather-related mortality Infectious diseases AirAir-quality respiratory illnesses Agriculture Crop yields Irrigation demands Forests Change in forest composition Shift geographic range of forests Forest health and productivity Source: EPA Potential Climate Change Impacts Water Resources Changes in water supply Water quality Increased competition for water Coastal Areas Erosion of beaches Inundation of coastal lands Costs to protect coastal communities Species and Natural Areas Shift in ecological zones Loss of habitat and species Source: EPA SeaSea-Level Rise Projections Global average sea level is p j projected to rise by 4 to 35 inches between 1990 and 2100 Source: IPCC TAR 2001 6 Who cares if sea level rises a foot or two? Effects of global warming on water cycle Global warming (temperature increase) Speeds up global water cycle More extreme weather events Droughts Storms Floods Prediction: Increase in frequency and intensity of droughts Are Extreme Weather Events Increasing? Extreme Precipitation Events in the U.S. Prediction: P di ti Increase in catastrophic flood events Source: Karl, 1996. 7 Potential effects on grain production Corn Wheat Rice What are the potential ecological effects of global climate change? Change in range distribution of plants and animals Change in the behavior of animals e.g., breeding behavior of birds link to day length, flowering of trees linked to temperature synchrony may be disturbed and result in reduced nesting success Decrease In Yield Increase In Yield No Change In Yield Source: IPCC, 2001 Predictions for range expansion of American Beech under two climate change scenarios Who in Ohio cares about tropical, mosquito-borne mosquitodiseases, like... Malaria? Yellow fever? c. Potential future range Current range Dengue fever? Antarctica More frequent growth of grasses during the last decade First ever documented flowering plants last year Increased snow Decreased penguin nesting success Greening of the North 8 Question 4: What are the projections for the near future? Models predict: 2oC increase in temperature by the end of the century Projected temperatures 2050-2059 relative to 1990 2050- Question 5: What level of uncertainty is there in the projections? p j Source: The Hadley Center for Climate Prediction and Research Two Scenarios For Change g In Rainfall All models are wrong...some are useful (George Box, 1975) Source: IPCC, 2001 Source: IPCC, 2001 9 What are the alternative points of view? Question: But...are we absolutely, 100% sure and certain that humans are responsible for global climate change? NO, however, large probability ...after all, this is SCIENCE! The climate is changing...(accepted scientific theory) But it's the result of normal, long term patterns of climate variation But th h B t the change will be for the better, since ill b f th b tt i crops grow better when it's warmer and there's more CO2 But it's only temporary; carbon "sinks" will increase to compensate for higher CO2 e.g., increased primary productivity What are the alternative points of view? The climate isn't changing... More clouds and dust from volcanoes will cancel out the greenhouse effect caused by elevated CO2 y Predictions are based on data and computer models that don't consider all relevant parameters e.g., cloud cover All models are wrong...some are useful (George Box, 1975) What we do know The climate is getting warmer CO2 levels are increasing Pre-industrial 260 ppm; today 360 ppm Prepp 2050 600 ppm Atmospheric chemistry is very complex Unknown variables: Biological systems Response of plants (CO2 removal) Degradation of "necrocarbon" (dead organic matter) by microbes, fungi (CO2 addition) Kyoto Agreement Framework agreed upon by 38 developed countries for reducing emissions of greenhouse gases 1997 Reduce emissions of CO2 by 5.2% compared to 1990 levels by 2012 Environmentalists not strict enough Industry will hinder economic development March 2001 Bush describes USA pulling out of the agreement as "It is not in the United States' economic best interest...I will not hurt our workers" U.S. is world's largest contributor of CO2 270 million consume more energy than 3.7 billion people in C. and S. America, India, Africa, China Two questions for you to ponder: Who is right? and 10 How long can you afford to wait for the answer before you act? Depends who you ask... Industry (Big Oil) Government (bye bye Kyoto) Environmental groups (the sky is falling) Scientists (yes, there is a change) 11 ...
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This note was uploaded on 04/18/2008 for the course BIO 101 taught by Professor Lanno during the Winter '08 term at Ohio State.

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