Lecture 28 Biodiversity

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Lecture 28Biodiversity Human Impact
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Global Changes Challenges

• Damage done to one of the worlds 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

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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

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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

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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

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The Ozone Hole CFC Pollution

• Starting in 1975, the earths ozone shield began
  to disintegrate creating an ozone hole

• 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

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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

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Reducing Pollution

• 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!

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Reducing Pollution

• 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

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Preserving Nonreplaceable Resources

• 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

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Preserving Nonreplaceable Resources

• 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 lt 10
• Agriculture consumes 85 of all freshwater
  resources

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Preserving Nonreplaceable Resources

• Biodiversity
• In the last 20 years, 1/2 of the worlds
  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
• Direct economic value of the products
• Indirect economic value of the benefits
• For example, water purification by marshlands
• Ethical and aesthetic value

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Loss of Biodiversity

• gt 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

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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

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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

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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

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California Condor _at_ Pinnacles Nat. Monument
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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

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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

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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

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Finding Other Sources of Energy

• Many countries are turning to nuclear power for
  their growing energy needs
• In 1995, gt 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

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The Costs of Nuclear Energy

• 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

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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

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Trends in Human Population Growth

• The worlds 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

• 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

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Consumption in the Developed World

• The vast majority of the worlds population is in
  developing countries
• However, the vast majority of resource
  consumption is in the developed world
• Wealthiest 20 of the worlds population accounts
  for 80 of worlds 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 worlds natural resources are already
  overtaxed

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Individuals Can Make the Difference

• And ecosystems can recover
• Two examples serve to illustrate this point
• The Nashua River in New England
• Lake Washington in Seattle

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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

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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 lakes 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

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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 many of 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!