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Lecture 28 Biodiversity & Human Impact

Lecture 28 Biodiversity & Human Impact

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Lecture 28 Biodiversity & Human Impact

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  1. Lecture 28Biodiversity &Human Impact

  2. Global Changes & Challenges • Damage done to one of the world’s ecosystems can have ill effects on many others • Widespread effects on the worldwide ecosystem are termed global change • Patterns of global change include • Pollution • Acid precipitation • Ozone hole • Greenhouse effect • Loss of nonreplaceable resources

  3. Chemical Pollution • Major problem because of growth of heavy industry and overly casual attitude in industrialized countries • Air pollution • Gray-air cities (include New York) • Pollutants are usually sulfur oxides emitted by industry • Brown-air cities (include Los Angeles) • Pollutants undergo chemical reactions in the sunlight • Water pollution • A serious consequence of our “Flushing it down the sink” attitude

  4. Modern agriculture also requires lots of fossil fuels: • The green revolution increased fossil fuel use in agriculture by 50-100% • Today it takes 1 calorie of fossil fuels to produce 1 calorie of food, excluding processing, packaging, & transportation • It takes 29% more energy to produce ethanol from corn than the amount of energy produced by the ethanol Modern Agricultural • The spread of “modern” agriculture introduced large amounts of chemicals into the global ecosystem • Pesticides, herbicides and fertilizers • Chlorinated hydrocarbons (such as DDT) caused severe environmental problems through biological magnification • Becoming more concentrated as they moved up the food chain

  5. Acid Precipitation: Sulfur Pollution • Sulfur combines with water vapor to produce sulfuric acid • Natural rain water has a pH of ~ 5.6 • In the northeastern US, the pH is ~ 4.3 • This pollution-acidified precipitation is called acid rain (acid precipitation) • In the 1950s, tall stacks were introduced to disperse sulfur-rich smoke into winds to disperse and dilute it • The problem was exported, not solved! • Acid precipitation destroys life • Forests and lake ecosystems in Europe and North America have been seriously damaged • The solution is to capture and remove emissions before their release • Problems in implementation • Who pays for the expense? • Polluter and recipient are far from one another

  6. The Ozone Hole: CFC Pollution • The culprit is a class of chemicals called chlorofluorocarbons (CFCs) that have been used since the 1920s as coolants and aerosol dispensers • Are very stable and thus have accumulated in the atmosphere over time • Catalyze the conversion of ozone (O3) into oxygen (O2) without being used up • Every 1% drop in ozone content is estimated to lead to a 6% increase in the incidence of skin cancers • Starting in 1975, the earth’s ozone shield began to disintegrate creating an ozone hole

  7. The Greenhouse Effect: CO2 Pollution • For over 150 years, our industrial society has been relying on the burning of fossil fuels • This has greatly increased atmospheric levels of carbon dioxide (CO2) • CO2 transmits radiant energy from the sun, but traps infrared light, or heat and creates what is known as the greenhouse effect • The accumulation of CO2 and other “greenhouse gases” (such as CFCs) have led to global warming or climate change • Average global temperatures could increase from 1oC to 4oC • Global warming will have serious effects on • Rain patterns • Areas experiencing droughts may see even less rain • Agriculture • The yields of some crops will increase, while the yields of other crops will decrease • Sea levels • Melting of large stores of ice will cause water levels to rise increasing flooding of low-lying lands

  8. Human activities are placing a severe stress on the biosphere Industrial pollution is one of the key problems It results from a failure of our economy to set a proper price on environmental health The reason is money! Economists have identified an “optimum” amount of pollution based on how much it costs to reduce pollution versus the social and environmental cost of allowing pollution However, The indirect costs of pollution often are not taken into account! Reducing Pollution

  9. In the US, three approaches have been proposed to curb pollution Antipollution laws All cars are required to eliminate automobile smog Catalytic converters, more efficient gas engines, hybrids, and alternate fuel vehicles are a result The Clean Air Act of 1990 requires that power plants eliminate sulfur emissions Pollution taxes In effect, a government-imposed price hike that adds the “hidden” environmental costs to the price of production. This can discourage consumption or encourage desired behavior The recycling tax on bottles and cans is an example Pollution trading (being tried in California) “Acceptable” pollution totals are set for each pollutant Companies own rights to pollute a given amount If one company wants to pollute more, or a new company wants to add pollution, they have to buy the rights from someone who is not using theirs or who will change behavior to produce less The cost of polluting then becomes subject to market values while the overall level of pollution is kept within target levels Reducing Pollution

  10. The consumption or destruction of nonreplaceable resources is the most serious problem humans face In addition to fossil fuels, key nonreplaceable resources are: Topsoil Groundwater Biodiversity Preserving Nonreplaceable Resources

  11. Topsoil Is being lost at a rate of centimeters per decade The US has lost 25% of its topsoil since 1950! Solutions Terracing to recapture lost topsoil Alternate farming methods that do not rely on nitrogen fertilizers Creating ethanol from corn is trading topsoil for energy! Creating ethanol from cellulose biomass is potentially better for the soil Groundwater Seeped into its underground reservoir very slowly during the last ice age over 12,000 years ago It is being wasted and polluted While we should all conserve our personal use of water It is also notable that if Californians quit watering all lawns (home and golf course) it would reduce California water use by < 10% Agriculture consumes 85% of all freshwater resources Preserving Nonreplaceable Resources

  12. Biodiversity In the last 20 years, ~ 1/2 of the world’s tropical rain forests have been either burned or cut Animal and plant species are becoming extinct Species from these areas have been the basis of many of our modern wonder drugs Marshes and swamps have been and continue to be drained for economic development They play a major role in cleaning the water in our aquifers Commercial seed companies are replacing local farmers’ seeds and reducing the genetic base of food crops In the early the 1970s 70% of the U.S. corn crop was lost to Southern corn blight due to the narrow genetic base of commercial seed corn Marine resources are being threatened by over fishing, pollution, and global warming. Loss of species entails three costs Directeconomic value of the products Indirecteconomic value of the benefits For example, water purification by marshlands Ethical and aesthetic value Preserving Nonreplaceable Resources

  13. Loss of Biodiversity • > 99% of species known to science are now extinct • Current rates of extinction are alarmingly high • Conservation biologists have identified three key factors • Habitat loss • Destruction • Pollution • Human disruption • Habitat fragmentation • Species overexploitation • Species that are hunted or harvested by humans are at great risk of extinction • Introduced species • The introduction of exotic species by humans has wiped out or threatened many native populations

  14. Preserving Endangered Species • Q: What is the most effective way to protect the environment and prevent extinctions of species? • A: Preservation of ecosystems and monitoring species before they are threatened! • Habitat restoration • Captive propagation • Sustaining genetic diversity • Preserving keystone species • Conserving ecosystems

  15. Habitat Restoration • In many situations, habitat conservation is no longer an option • Three programs for restoration, depending on the cause of the habitat loss • Pristine restoration • Removing introduced species • Cleanup and rehabilitation

  16. Captive Propagation • Recovery programs often involve direct intervention in natural populations to avoid extinctions • Case History: The Peregrine Falcon • Population disappeared east of the Mississippi by 1960 • The culprit was DDT • Causes eggs to break before they hatch • DDT was banned by federal law in 1970 • Captive breeding program started using falcons from other parts of the country • Very good results • California Condor: Another captive breeding program showing success

  17. California Condor @ Pinnacles Nat. Monument

  18. Sustaining Genetic Diversity • Smaller populations have little genetic diversity • Case History: The Black Rhino • All five species of rhinoceros are critically endangered • Black rhinos live in 75 small, widely separated populations • To increase genetic diversity, individuals must be moved between populations

  19. Preserving Keystone Species • Removal of keystone species can have disastrous consequences on ecosystems • Case History: Flying Foxes • Widespread on the South Pacific Islands • Often the only pollinator and seed disperser • Were being driven to extinction by human hunting • Legal protection, habitat restoration, and captive breeding have produced a very effective preservation program

  20. Conserving Ecosystems • Isolated patches of habitat lose species far more rapidly than large areas do • Conservation biologists have therefore promoted the following • The creation of mega reserves, Large areas of land that contain a core of one or more undisturbed habitats • The preservation of intact ecosystems • This has been a primary issue of contention with the Alaskan oil pipelines • In addition to the potential for accidental pollution • They create barriers across the habitat and migratory routes of many large arctic animals

  21. Finding Other Sources of Energy • Many countries are turning to nuclear power for their growing energy needs • In 1995, > 500 nuclear reactors were producing power worldwide • In the US, nuclear power plants have not been popular because of • Ample access to cheap coal • Public fears of the consequences of an accident • Three Mile Island nuclear plant in 1979 • Chernobyl nuclear plant in 1986

  22. Nuclear power may provide plentiful cheap energy; however, several problems must be overcome: Safe operation Fears of vast radioactive contamination Waste disposal Spent nuclear fuel remains radioactive for thousands of years Security Fears of terrorists getting their hands on plutonium Insuring energy payback Is nuclear really an alternative energy? In a study for the U.S. Department of Energy in the 1960s, Howard Odum showed that the amount of fossil fuel energy required to: Mine and refine the uranium Build & maintain the nuclear power plant Deactivate the plant at the end of its life Was equal to the amount of nuclear generated electricity the plant produced during its life Note that his calculations did not include storing and monitoring the radioactive waste for hundreds or thousands of years The Costs of Nuclear Energy

  23. Human Population Growth • The human population has grown explosively over the last 300 years • Worldwide • Birth rate has stabilized to ~ 21 per year per 1,000 people • Death rate has fallen to ~ 9 per year per 1,000 people • This amounts to a population growth rate of 1.3% per year • The world population will double in 54 years! • One of the most alarming trends is massive movement of people towards urban centers

  24. The world’s population growth is unevenly distributed among countries Growth rate in developed countries is 0.1% per year Growth rate in developing countries is 1.9% per year Trends in Human Population Growth • The world population growth rate has been declining • The United Nations attributes the decline to • Increased family planning efforts • Increased economic power and social status of women • Slowing population growth helps sustain resources, but per capita consumption is also important

  25. Consumption in the Developed World • The vast majority of the world’s population is in developing countries • However, the vast majority of resource consumption is in the developed world • Wealthiest 20% of the world’s population accounts for 80% of world’s resource consumption • Poorest 20% is responsible for only 1.3% of consumption • This disparity can be quantified by calculating the ecological footprint • The amount of productive land required to support a person throughout his or her life • As countries like China & India strive to attain our lifestyle, their ecological footprint expands • The world’s natural resources are already overtaxed

  26. And ecosystems can recover Two examples serve to illustrate this point The Nashua River in New England Lake Washington in Seattle Individuals Can Make the Difference

  27. The Nashua River • By the 1960s, was severely polluted by wastes from mills set up along its banks • Marion Stoddart organized the Nashua River Cleanup Committee in 1962 • Industrial dumping is now banned and the river has largely recovered • Greatly aided passage of the Massachusetts Clean Water Act of 1966

  28. Lake Washington • By the 1950s, sewage dumping and fertilizer runoffs had caused a bloom of blue-green algae • Bacteria decomposing dead algae would eventually deplete the lake’s oxygen • In 1956, W.T. Edmondson of the University of Washington began a campaign to alert public officials of the danger • A sewer was built to carry sewage effluent to the sea • The lake is now clean

  29. Solving Environmental Problems • Coming to grips with a widely ignored ethical issue in our society: • Is generating profits (or comfort) for ourselves by forcibly shifting the costs (or discomfort) to someone else (present or future) ever ethical? • Recognizing that our own lifestyles (belief systems & behaviors) are contributing to or causing manyof these problems • Technology may help us solve some problems and still maintain our lifestyle • Ultimately we all need to ask ourselves how we are willing to change – and what are we willing to give up (sacrifice) – to keep our planet habitable by humans? • If you are ready to get involved in community issues, here are five components for successfully solving an environmental problem • Assessment • Risk analysis • Public education • Political education • Follow-through • Doing nothing has the potential of destroying our planet as we know it • Life will likely go on regardless of what we do • Just not human life!