Environmental science - conditions for life on Earth

  • Created by: zbeale
  • Created on: 21-02-19 20:13
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  • Conditions for life on Earth
    • The conditions that allowed life to develop and survive
      • position in solar system
        • suitable temperature - the sun is stable/not too big
      • orbital behaviour
        • tilt, rotation and orbit controls daily/seasonal variations
      • atmosphere
        • protects Earth from UV and meteors
        • reduces variability of temperatures
        • prevents water and gases being lost to space
        • gaseous resource
      • Magnetosphere
        • deflects harmful short wave radiation
      • water
        • protected early life from UV
        • high specific heat capacity
          • causes water to warm and cool slowly which moderates temperature changes
        • good solvent
          • physiological solvent - most chemical reactions in cells take place in water
          • solvent in blood/sap, transports essentials - O2, nutrients, sugars
        • water cycle
        • Ice
          • ice floats stops water below from cooling as much and freezing so life can survive under ice
        • provision of aquatic habitats
    • water
      • protected early life from UV
      • high specific heat capacity
        • causes water to warm and cool slowly which moderates temperature changes
      • good solvent
        • physiological solvent - most chemical reactions in cells take place in water
        • solvent in blood/sap, transports essentials - O2, nutrients, sugars
      • water cycle
      • Ice
        • ice floats stops water below from cooling as much and freezing so life can survive under ice
      • provision of aquatic habitats
    • old methods of measuring past climate
      • ancient landforms
        • relict cliffs mean sea levels were higher
        • u shaped valleys were eroded by glaciers = cooler
        • erosion will eventually remove all landforms created in past so can only be used in recent past
        • tectonic plates move - affect climate due to location in world
        • some landforms may be difficult to interpret
      • palynology/ pollen analysis
        • pollen preserved in lake/peat bog deposits can be analysed to show past vegetation
        • can be contaminated as pollen can travel large distances
        • different species produce different amounts of pollen
        • may overestimate pollen transferred by wind rather than insects
        • pollen may not be found if the area wasn't colonised fast after the ice age. It doesn't mean area had unsuitable climate
      • dendro chronology tree rings
        • if planet is warmer more growth, wider rings
        • can be used to work out what temps and water may have been
        • tree growth can be affected by many factors - drought, disease, forest fires
        • local variation and species variation
        • qualitative and not very precise
        • only for the past few thousand years
      • Coral heads
        • some coral produce large heads with annual growth rings which can be used to  estimate past sea  temperatures
      • Cave art and historical records
        • paintings of woolly mammoths  could indicate cooler
        • many paintings of frost fairs on River Thames in 17th century
        • people may have painted things for many reasons
        • accounts of  weather throughout almost entire human history - extreme weather
        • met office since 1880
      • problems
        • proxy data -don't tell specific temperature
        • general lack of historical data with many large gaps/time periods with little evidence
        • early equipment lacked accuracy
        • lack of data collection on a global scale
        • temperature records in towns may show warming that is caused by an increase in the heat-island effect
    • new methods of measuring climate
      • Ice cores
        • as snow and ice is laid down over thousands of years air is trapped
        • bubbles of air can be analysed and used to estimate  past co2 concentration
        • oxygen isotopes  in ice cores (16+18) are temp dependent and can tell us past temperatures
        • volcanic dust layers also help comparison between areas
      • Satellite data
        • sensors carried by satellites are used to collect data for wind velocity, ocean currents, temp, wave height, ice and vegetation cover
        • LEO (low earth  orbit) satellites collect detailed info on whole of Earth's surface
        • geostationary satellites get less detailed info from a constant position above equator
      • ocean currents
        • surface currents are monitored with satellites, buoys/floats
        • deeper currents can be monitored with drifting floats like the Argo floats which are programmed to sink for specific durations
        • data is collected on temp and salinity. sequence of position plots shows direction and speed of current
      • computer models
        • allows the impact of interconnections and their consequences to be estimated
        • model can be tested by using old data and seeing if it predicts the outcome for a later year
        • model can  be continually modified using more data and by analyzing differences between predicted and real outcomes
        • the IPCC collects the data for models

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