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SBI4UZ Topic 4: Ecology (4.4 Climate Change (Greenhouse Debate (Climate…

- - - - Population: group of same species living in same area, same time
        
        Community: group of populations living together, interacting w/in given area
  - - - Inorganic substances (obtained from abiotic environment) into own organic molecules, energy derived from sunlight (photosynthesis) or through oxidation of inorganic molecules (chemosynthesis)
      - Carbon, nitrogen, hydrogen, oxygen, phosphorus obtained from air/water/soil
    - - Obtains organic molecules from other organisms (either living/recently killed or non-living remains)
        
        Consumers: ingest organic molecules from living/recently killed
        
        Herbivores: feed on plant matter
        
        Carnivores: feed on animal matter
        
        Omnivores: principle diet copmosed of both plant and animal matter
        
        Scavengers: feed on dead/decaying carcasses instead of hunting live prey
        
        Detritivores: ingest organic molecules found in non-living remnants (detritus: dead particulate organic matter or humus: decaying leaf litter mixed w/in topsoil)
        
        Saprotrophs: release digestive enzymes, absorb external products of digestion (decomposers)
  - - - Heterotrophs ingest these compounds and use them for growth and respiration, releasing inorganic byproducts
        
        Sapotrophs decompose dead remains and free inorganic materials into soil
        
        Continual supply of raw materials for autotrophs
- - - - Level 1: producer
      - Level 2: primary
      - Level 3: secondary
  - - - Higher trophic levels store less energy as carbon compounds, have less biomass: total mass of group of organisms (scientists can measure amount of energy added to organisms as biomass; diminishes along food chains w/ loss of CO2, water, waste products)
      - Number of potential trophic levels limited → need to eat larger quantities to obtain sufficient amounts, higher trophic levels receive less energy
      - Higher trophic levels spend more energy/biomass hunting for food b/c they need to eat more → if energy required to hunt exceeds energy from food, trophic level becomes unviable
- - - - Methane: methanogens are archaean microorganisms that produce methane as metabolic byproduct in anaerobic conditions (i.e. wetlands, marine sediments, digestive tract of ruminant animals)
        
        Acetic acid → methane and CO2
        
        CO2 and hydrogen → methane and water
        
        Either accumulates underground or diffuses into atmosphere (rising global numbers of cattle may be increasing levels of methane in atmosphere)
        
        Methane naturally oxidized to form CO2 and water; only persists for ~12 years
      - Combustion: organic compounds rich in hydrocarbons heated in oxygen; exergonic reaction and releases CO2 and water, increasing CO2 concentration in the atmosphere
        
        Fossil fuels: organic compounds become rich in hydrocarbons when compacted underground
        
        Biomass: living organisms produce hydrocarbons as part of total biomass → can be extracted and purified to produce alternative renewable fuel source
    - - Aquatic Conversions
        
        CO2 dissolves in water: some remains as dissolved gas, remainder will combine with water to form carbonic acid (equilibrium)
        
        Carbonic acid dissociates to form hydrogen carbonate ions (equilibrium)
        
        Releases H+ ions (why pH changes when CO2 dissolved in water)
        
        Autotrophs absorb both dissolved CO2 and hydrogen carbonate ions to produce organic compounds
        
        When hydrogen carbonate ions come into contact with rocks, they acquire metal ions → calcium carbonate → limestone
        
        Living animals may combine hydrogen carbonate ions with calcium to form CaCO3 which forms hardened exoskeleton of coral and mollusca shells
        
        When organism dies and settles to sea floor, these compounds become fossilised in limestone
    - - Carbon Compounds
        
        Autotrophs convert inorganic CO2 into organic compounds via photosynthesis
        
        CO2 should always be higher concentration in atmosphere b/c photosynthesis → concentration gradient ensures CO2 will passively diffuse into autotrophic organism as required
        
        If there is more net photosynthesis than cellular respiration, atmospheric CO2 levels drop
        
        If there is more net respiration than overall photosynthesis, CO2 levels should increase
        
        All organisms produce ATP to power metabolic processes via cell respiration (breakdown of organic molecules and creates CO2 as byproduct)
    - - Fossil fuels
        
        Partial decomposition: saprotrophic bacteria and fungi decompose dead organisms and return nutrients to soil for cycling; waterlogged regions possess anaerobic conditions → produce organic acids (bacteria and funi can't function effectively in anaerobic/acidic conditions, preventing decomposition)
        
        Coal formation: organic matter not fully decomposed in waterlogged soils, carbon-rich molecules remain in soil and form peat → deposits of peat compressed under sediments, heat and pressure force out impurities and remove moisture → undergoes chemical transformation to form coal
        
        Oil/natural gas: sediments deposited on top of dead margine organisms creating anoxic conditions and preventing decomposition → burial and compaction causes heat and hydrocarbons form → hydrocarbons form oil and gas which are forced out of source rock and accumulate in porous rocks (sandstone) ** formation of these fossil fuels takes place over millions of years making them non-renewable
- - - - Water vapour created via evaporation and transpiration; removed via precipitation
      - Carbon dioxide made by cellular respiration and burning fossil fuels; removed via photosynthesis, absorption by oceans
      - Methane: emitted from waterlogged habitats, gaseous waste produced by ruminants
      - Nitrogen oxides: released naturally by bacteria and in exhaust
    - - Ability to absorb long-wave radiation (greater capacity to absorb long-wave radiation have greater impact)
      - Concentration w/in atmosphere: greater concentration = greater impact; determined by release rate and persistence in atmosphere
      - Examples
        
        Methane has large absorption capacity BUT less abundant
        
        Water vapour enters atmosphere rapidly but remains for short periods
        
        Carbon dioxide persistent
        
        Human activity increasing greenhouse gases = greater impact
  - - - More frequent extreme weather conditions
      - More drought in some areas while other areas become more prone to more rainfall
      - Changes to ocean currents
    - - Ice cores taken from Antarctica, gas bubbles analyzed for historical CO2 levels and air temperatures → strong positive correlation b/t CO2 concentrations and temperature, fluctuating cycles of CO2 concentrations correlate w/ global warm ages and ice ages
      - Current temperatures highest ever than in the last 400,000 years
  - - - Shells and coral exoskeletons to dissolve
      - Disappearance of coral reefs results in loss of shoreline protection and habitat
      - Loss in tourism and food industries could cost $1 trillion+
      - Increasing dissolved CO2 levels would cause invasive algae species to flourish (more photosynthesis)
  - - - Counter: climate changes do occur naturally, but not as abruptly; all abrupt occurrences led to high destruction to life; atmosphere CO2 levels correlate to avrg. temps. and are the highest ever recorded
    - - Counter: sun has shown slight cooling trend but global temps. have increased
    - - Counter: rate at which sea levels have risen is greater than that seen in last 200 years
    - - Although different models predict different reliance on fossil fuels, all three predict increase in average global temps.
    - - Counter: living things require constant internal environments -- small external changes have big impacts