Human Impacts upon Earth

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• Human Impacts upon Earth
• Historical Basis of Pollution
• Pollution Human released products in the
  amounts and durations that cause adverse effects.
• Two primary factors that affect damage done
• technological inventions
• population size 
• Biodegradable
• Easily broken down into simpler compounds
• Non-biodegradable
• Wont break down or break down very slowly

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• Population size wastes produced faster than
  ecosystem could dispose.
• Sewage
• Urban centers enhanced this problem. 
• Eliminate misery and disease often causes
  other problems.
•  
• Pesticides.
•  
• Often, pollution is in the eye of the beholder.
• Uranium ore
• arsenic in water

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• Renewable and Nonrenewable Resources
• Natural Resources things usable by humans, but
  which cannot be created by humans.
• limited and unlimited
• intensive exploitation moves unlimited to limited
  resources.
•  
• renewable
• vs. natural
• nonrenewable processes

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• Mineral Resourcesnon-renewable
• Locations of mineral resources is not based on
  political boundaries
• international trade required to bring in all
  types needed
• (U.S. Canada has about 5.2 of worlds
  population, and consumes about 30 of mineral
  resources.)
• Costs
• Economic Costs ( to exploit resource)
• Energy Costs (to do the exploiting)
• Environmental Costs (pollution, habitat loss etc)

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• Steps each step has costs
•  Exploration
• time technology
• some energy
• some environmental
• becomes more intense as easy resources are
  consumed.
• Mining
• Labor
• Equipment
• Energy (large costs)
• Environmental (significant)
• mine tailings
• water pollution erosion
• land disturbance

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• Refining (often part of mining)
• labor
• equipment
• energy
• environmental
• air pollution
• water pollution
• Transportation
• energy
• some environmental
• Manufacturing
• labor
• equipment
• energy
• environmental

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• Recycling
• Can save significant costs by using materials
  which do not require all of the above steps. 
• As energy costs go up, recycling will become more
  common. 
• Many pay the environmental costs, rather than the
  few who use a product.
• H/W must be able to collect easily and must have
  high economic value

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• Pristine Areas
• Remote areas with harsh conditions are typically
  pristine (e.g. arctic poles, mountain tops, open
  ocean)
• Areas that wont support agriculture.
• Wont support dense human population
• Other areas which until recently have been
  unaffected are being impacted.
• will support limited agriculture or other human
  uses.
•  
• As human population grows.....

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• Many parks and protected areas have been
  designated as pristine areas become more rare.
•  
• Wilderness areas where humans are visitors,
  and do not remain. (U.S. definition)
• Parks becoming more noticeable in Africa, C/S/N
  America, Australia
• Until recently had large amount of relatively
  untouched land, now trying to preserve it

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• Modifications by Humans
• About 40 of worlds land surface converted to
  cropland and permanent pasture.
• Forest
• Originally, 1/2 of U.S., 3/4 of Canada, 9/10 of
  Europe, and much of rest of world.
• Very large demand for wood.
• Sustained yield harvest rate equals rate of
  regrowth.
• Tropical forests are currently treated as
  nonrenewable resource, with extremely fast rate
  of depletion

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• Forests reduce energy in rainfall, and
  practically stop erosion by slowing runoff.
• Water is evapo-transpirated in large volumes.
• Shade and humidity moderate temperature
  extremes.
• Tropical forests trap much CO2 but are in areas
  of highest population growth pressures.

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• Management of forests require a compromise
  between economic forces and environmental
  viewpoints.
• Clear-cutting
• Patchwork clear-cutting
• Selective harvesting
• Reforestation
•  Different species need different things in a
  forest (e.g. Red-Cockaded Woodpecker)

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• Deciding what to do with a forest requires a
  conscious decision
• known value of worlds forests
• can assign value to wildlife and water within
• Wilderness value is very difficult to determine
  .... and forest can not be both an economic
  resource and a wilderness area.
• Have to choose in some cases or find way to
  satisfy both sides of issue

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• Rangelands 
• Arid and semiarid lands that cant support
  typical agriculture, but can support some grazing
  animals. 
• Grazing animals selectively reduce some plant
  species (and inadvertently encourage others).
  Managers do the same. 
• Most grazing animals which are herded are
  exotic species, and reduce native species.
• Population pressures force people to graze too
  many animals (Tragedy of the Commons), remove
  trees for wood (nutrient removal) and push land
  towards desertification.

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• Aquatic Systems
• Large areas of the ocean are still considered
  pristine.
• Most productive areas in the oceans are close to
  shore
• nutrients/sunlight/ offshore currents bring
  nutrients up from bottom
• Concentrates pressure
• Fishing selectively removes some species.
•  
• Methods for catching bottom dwellers disturbs
  habitat and wastes 25 of fish caught

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• Most freshwater systems have been altered by
  humans.
• water quality changes
• exotic species
• thermal pollution
•  
• Many systems are manipulated to enhance some
  desirable species.
• Recreational and commercial interests
• Difficult to predict all the consequences of
  managing large natural systems.
• Difficult to manage all inputs to lake that may
  affect ecosystem

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• Wildlife Management
• Improving conditions for species desirable to
  humans. Manipulate one of the following 
• -food and water
• -cover (shelter)
• -escape from competitors
• -protection from weather
• -resting and sleeping
• -mating and raising young
• Quail

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• Must understand niche very well before attempting
  habitat management.
•  
• Trying to improve the habitat for one species
  often harms the habitat of another.
• Difficult role to try and take over mgmt of
•  
• Migrating species require special considerations.

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• Natural Selection and Extinction
• Extinction elimination of all individuals of a
  particular species (local and global).
•  
• Natural phenomenon .... estimated that only about
  1 or 2 of all species which have existed are
  still alive today.
•  
• Speciation appearance of a new species.
• Since things change, a species must adapt or
  become extinct.

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• Extinction happens more often when 
• species has small population/low reproduction
  rate
• dispersed individuals
• species occurs in small, restricted areas
• species is very specialized

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• Accelerated Extinction
• Humans are among the most successful species
  currently on earth
• adaptable
• Intelligent
• high reproductive capability
• few enemies
• As human population grows
• other species displaced (habitat alteration)
• species utilized as food
• used as ornaments
• used for medicine
• eliminated as pests
• accelerated extinction

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• Why worry?
•  
• Many species may be useful to us.
• food medicine
•  
• Certain species play key roles in the ecosystems
  that we utilize.
•  
• Most people find nature beautiful, and
  monocultures are found disturbingly sterile.
•  
• Do all species have a fundamental right to exist?

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• Actions
• Protection of threatened and endangered
  species.
•  
• More action in developed nations than in less
  developed nations.
•  
• Bias in protecting certain types of species
• birds
• mammals
• butterflies
• a few mollusks, fish and plants

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• World Conservation Union (former International
  Union for the Conservation of Nature)
• Work (without much power, but much prestige)
  around the world, especially in less developed
  nations.
• U.S. Endangered Species Act (1973) 
• Attempts to protect threatened and endangered
  species from governmental actions.
• Political amendments and effects
• Endangered Species Review Committee
• Can sanction extinction if economic benefits
  warrant
• Weakened ability to add species to list